UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

(Mark One):

For the fiscal year ended December 31, 20092010

For the transition period from              to             

Commission File Number: 001-14195

American Tower Corporation

(Exact name of registrant as specified in its charter)

116 Huntington Avenue

Boston, Massachusetts 02116

(Address of principal executive offices)

Telephone Number (617) 375-7500

(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act:

None

Indicate by check mark if the registrant is a well known seasoned issuer, as defined in Rule 405 of the Securities Act:    Yes  x    No  ¨

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act:    Yes  ¨    No  x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days:    Yes  x    No  ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes  x    No  ¨

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of the Form 10-K or any amendment to this Form 10-K.  x

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See definition of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act. (Check One):

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act):    Yes  ¨    No  x

The aggregate market value of the voting and non-voting common stock held by non-affiliates of the registrant as of June 30, 20092010 was approximately $12.4$17.7 billion, based on the closing price of the registrant’s Class A Common Stock as reported on the New York Stock Exchange as of the last business day of the registrant’s most recently completed second quarter.

As of February 12, 2010,11, 2011, there were 402,669,455397,612,895 shares of Class A Common Stock outstanding.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the definitive proxy statement (the “Definitive Proxy Statement”) to be filed with the Securities and Exchange Commission relative to the Company’s 20102011 Annual Meeting of Stockholders are incorporated by reference into Part III of this Report.

AMERICAN TOWER CORPORATION

TABLE OF CONTENTS

FORM 10-K ANNUAL REPORT

FISCAL YEAR ENDED DECEMBER 31, 20092010

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AMERICAN TOWER CORPORATION

TABLE OF CONTENTS—(Continued)

FORM 10-K ANNUAL REPORT

FISCAL YEAR ENDED DECEMBER 31, 20092010

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This Annual Report contains statements about future events and expectations, or forward-looking statements, all of which are inherently uncertain. We have based those forward-looking statements on our current expectations and projections about future results. When we use words such as “anticipates,” “intends,” “plans,” “believes,” “estimates,” “expects,” or similar expressions, we do so to identify forward-looking statements. Examples of forward-looking statements include statements we make regarding future prospects of growth in the communications site leasing industry, the level of future expenditures by companies in this industry and other trends in this industry, the effects of consolidation among companies in our industry and among our customers,tenants, our ability to maintain or increase our market share, our future operating results, our consideration to elect real estate investment trust status, our future purchases under our stock repurchase program, our future capital expenditure levels, our future financing transactions and our plans to fund our future liquidity needs. These statements are based on our management’s beliefs and assumptions, which in turn are based on currently available information. These assumptions could prove inaccurate. These forward-looking statements may be found under the captions “Business” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations,” as well as in this Annual Report generally.

You should keep in mind that any forward-looking statement we make in this Annual Report or elsewhere speaks only as of the date on which we make it. New risks and uncertainties arise from time to time, and it is impossible for us to predict these events or how they may affect us. In any event, these and other important factors, including those set forth in Item 1A of this Annual Report under the caption “Risk Factors,” may cause actual results to differ materially from those indicated by our forward-looking statements. We have no duty to, and do not intend to, update or revise the forward-looking statements we make in this Annual Report, except as may be required by law. In light of these risks and uncertainties, you should keep in mind that the future events or circumstances described in any forward-looking statement we make in this Annual Report or elsewhere might not occur.

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PART I

Overview

We are a leading wireless and broadcast communications infrastructure company that owns, operates and develops owns, and operatescommunications sites. Our primary business is leasing antenna space on multi-tenant communications sites to wireless service providers and radio and television broadcast companies. We refer to this business as our rental and management operations, which accounted for approximately 98% of our total revenues for the year ended December 31, 2010. We also offer tower-related services domestically, including site acquisition, zoning and permitting services and structural analysis services, which primarily support our site leasing business and the addition of new tenants and equipment on our sites.

Our communications site portfolio includes wireless communications towers, broadcast communications towers and distributed antenna system (“DAS”) networks.networks, which are collocation solutions to support seamless in-building and outdoor wireless coverage. Our portfolio of wireless and broadcast towers consists of towers that we own and towers that we operate pursuant to long-term lease arrangements, including, as of December 31, 2009,2010, approximately 20,00020,900 towers in the United Statesdomestically and approximately 7,00013,900 towers in Mexico, Brazil and India.internationally. Our portfolio also includes approximately 200 in-building and outdoor DAS networks that we operate in malls, casinos and other in-building applications, in the United States and Mexico and oneselect outdoor DAS network in development in the United States.environments. In addition to the communications sites in our portfolio, we manage rooftop and tower sites for property owners in the United States, Mexico and Brazil.

Our primary business is leasing antenna space on multi-tenant communications sites to wireless service providers and radio and television broadcast companies. This segment of our business, which we refer to as our rental and management segment, accounted for approximately 97%, 97% and 98% of our total revenues for the years ended December 31, 2009, 2008 and 2007, respectively. Through our network development services segment, we also offer tower-related services in the United States, including site acquisition, zoning and permitting services and structural analysis services, which directly support our site leasing business and the addition of new tenants and equipment on our sites.

We have historically focused on our rental and management segment due to its high operating leverage and low cash flow volatility when compared to our network development services segment. Our rental and management segment has generated consistent incremental growth in revenue and cash flows due to the following characteristics:

Additionally, our communications site portfolio provides us with growth potential because we have the ability to add new tenants, and new equipment for existing tenants, on our sites. In the United States, our largest geographic area, our nationwide network of communications sites enables us to address the needs of national, regional, local and emerging wireless service providers. Our diverse site portfolio and our established customer base provide us with a diverse source of new business opportunities, which has historically resulted in consistent and predictable revenue growth. Our operations in the United States accounted for approximately 85%, 86% and 87% of our total revenues for the years ended December 31, 2009, 2008 and 2007, respectively.

Our international site leasing business, which is comprised of communications sites in Mexico, Brazil and India, provides a source of diversification and growth for our rental and management segment. Our international site leasing business accounted for approximately 15%, 14% and 13% of our total revenues for the years ended December 31, 2009, 2008 and 2007, respectively. In developing our international site portfolio, we have focused on building and acquiring communications sites in high demand areas to meet the needs of our customers.

Strategy

Our strategy is to capitalize on the growth in the use of wireless communications services and the expanding infrastructure required to deploy current and future generations of wireless communications technologies. We believe that, based on current trends, wireless service providers in each of our existing geographic areas will continue to invest in their networks to meet demand from their new and existing subscribers. Wireless communications services have experienced significant growth in our domestic and international businesses:

Wireless Service Growth

According to industry data, in the United States, total voice minutes of use increased to over 1.1 trillion for the six months ended June 30, 2009, representing a year-over-year increase from the prior year period of approximately 3%. Further, as of June 30, 2009, revenue attributable to data services increased from the prior year period to over 27% as a percent of total service revenues for the nationwide wireless service providers. To meet the needs of growing voice and data service usage, cell sites in the industry (i.e., the number of antenna arrays and related equipment in commercial operation, not the number of towers on which that equipment is located) increased to approximately 245,900 as of June 30, 2009, representing a year-over-year increase from the prior year period of 12%.

We believe the growth in the number of wireless service subscribers, the minutes of use per subscriber and the further adoption of wireless data applications by subscribers will require wireless carriers to add new cell sites and new equipment to existing cell sites to maintain the performance of their networks in the areas they currently cover and to extend service to areas where coverage does not yet exist. As wireless carriers continue to add subscribers and seek to limit churn, we anticipate they will focus on network quality as a competitive necessity and will continue to invest in equipment upgrades that increase the capacity and overall quality of their networks.

In addition, we believe that as the usage of wireless data applications, such as email, internet access and video, continues to grow on a widespread basis, wireless carriers may be compelled to further increase the cell density of their existing networks, deploy new technology and equipment, and expand their network coverage. To meet this demand, we believe wireless carriers will continue to outsource their communications site infrastructure needs as a means to accelerate access to their markets and more efficiently use their capital, rather than construct and operate their own communications sites and maintain their own communications site service and development capabilities.

We believe that our existing portfolio of communications sites, our tower-related services and our management team position us to benefit from these trends and to play an increasing role in addressing the needs of wireless service providers and broadcasters. The key elements of our strategy include:

The Companyowners.

American Tower Corporation was created as a subsidiary of American Radio Systems Corporation in 1995 to own, manage, develop and lease communications and broadcast tower sites, and was spun off into a free-standing public company in 1998. Since inception, we have grown our communications site portfolio through acquisitions, long-term lease arrangements, development and construction of sites, and through mergers with and acquisitions of other tower operators, increasing the size of our portfolio to over 27,200 communications sites.operators.

American Tower Corporation is a holding company, and we conduct our operations through our directly and indirectly owned subsidiaries. Our principal United Statesdomestic operating subsidiaries are American Towers, Inc. (“ATI”) and SpectraSite Communications, LLC (“SpectraSite”). We conduct our international operations through our subsidiary, American Tower International, Inc., which in turn conducts operations through its various international operating subsidiaries. Our international operations consist primarily of our operations in Brazil, Chile, Colombia, India, Mexico Brazil and India.Peru. In addition, as previously disclosed, we have entered into definitive agreements to acquire communications sites in South Africa and Ghana, and subject to customary closing conditions, we expect to close on initial tranches of communications sites during the first half of 2011.

We operateIncreased expansion activity in international markets and changes to our organizational structure have led us to separately disclose our rental and management operations in two businessreportable segments: domestic rental and management and international rental and management. Through our network development services segment, we also offer tower-related services domestically. Accordingly, our continuing operations are reported in three segments, domestic rental and management, international rental and management and network development services. For more information about our business segments, as well as financial information about the geographic areas in which we operate, see Item 7 of this Annual Report under the caption “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and note 18 to our consolidated financial statements included in this Annual Report.

Products and Services

Rental and Management SegmentOperations

Our primary business is our communications site leasing business, which we conduct through our rental and management segment. This segmentoperations accounted for approximately 97%98%, 97% and 98%97% of our total revenues for the years ended December 31, 2010, 2009 2008 and 2007,2008, respectively. Our tenants lease space on our

communications site infrastructure, where they install and maintain their individual communications network equipment. Our revenue is primarily generated from tenant leases, and the annual rental payments vary considerably depending upon various factors, including but not limited to, tower location, amount of tenant equipment on the tower, ground space required by the tenant, and remaining tower capacity. Our tenant leases are typically non-cancellable and have annual rent escalations. Our primary costs typically include ground rent, property taxes and repairs and maintenance, which are primarily fixed, with annual cost escalations. In our international markets, a portion of our operating costs is passed through to our tenants, such as ground rent and fuel costs. Our rental and management operations have generated consistent incremental growth in revenue and have low cash flow volatility due to the following characteristics:

Our domestic rental and management segment is comprised of our nationwide network of communications sites that enable us to address the needs of national, regional, local and emerging communications service providers. Our domestic rental and management segment accounted for approximately 79%, 82% and 83% of our total revenues for the years ended December 31, 2010, 2009 and 2008, respectively.

Our international site leasing business, includingrental and management segment, which is comprised primarily of communications sites in Brazil, Chile, Colombia, India, Mexico and Peru, provides a source of diversification and growth. Our international rental and management segment accounted for approximately 19%, 15% and 14% of our total revenues for the years ended December 31, 2010, 2009 and 2008, respectively.

Our rental and management operations include the operation of wireless communications towers, broadcast communications towers and DAS networks, as well as rooftop management.

Wireless Communications Towers.We are a leading independent ownerown and operator ofoperate wireless communications towers in the United States, Brazil, Chile, Colombia, India, Mexico and Brazil, based on numberPeru. Approximately 93%, 94% and 92% of towers and revenue. We also own and operate communications towersrevenue in India, where we commenced operations in the second half of 2007. In addition to owning wireless communications towers, we also manage wireless communications sites for property owners in the United States, Mexico and Brazil. Approximately 94%, 92% and 91% of our rental and management segment revenuesegments was attributable to our wireless towers for the years ended December 31, 2010, 2009 and 2008, and 2007, respectively. As of December 31, 2009, our wireless tower portfolio included the following:

We lease space on our wireless communications towers to customerstenants in a diverse range of wireless industries,services, including personal communications services, cellular, enhanced specialized mobile radio, WiMAX, paging and fixed microwave. Our threefour largest wireless customersdomestic and international tenants by revenue in each country are as follows:

Accordingly, we are subject to certain risks, as set forth in Item 1A of this Annual Report under the caption “Risk Factors—Due to the long-term expectations of revenue growth from tenant leases, we are sensitive to changes in the credit worthinesscreditworthiness and financial strength of our tenants” and “A substantial portion of our revenue is derived from a small number of customers.” In addition, we are subject to risks related to our international operations, as set forth under the caption “Risk Factors—Our foreign operations are subject to economic, political and other risks that could materially and adversely affect our revenues or financial position.”

Our leasesposition, including risks associated with wireless communications providersfluctuations in the markets we serve generally have initial non-cancelable terms of five to ten years. In most cases, our tenant leases have multiple five-year renewal terms

at the option of the tenant. Wireless carriers generally renew their leases with us because suitable alternative sites may not exist or be available and repositioning a site in an existing carrier’s network may be expensive and often requires reconfiguring several other sites within the carrier’s network, which may impact the carrier’s network quality and coverage and may also require the carrier to obtain other governmental permits. Most of our tenant leases have escalation provisions that periodically increase the rent due under the lease. These automatic increases are typically annual and are based on a fixed percentage (generally three to five percent), inflation or a fixed percentage plus inflation.

Annual rental payments vary considerably depending upon various factors including:

The number of antenna arrays that our towers can accommodate varies depending on the tower’s location, height, and structural capacity at certain wind speeds. As of December 31, 2009, our towers had an average of approximately 2.4 tenants per tower. We believe that a significant majority of our towers have the capacity to add new tenants, and new equipment for existing tenants, without the need to make capital investments to augment the structure. We believe that nearly all of our towers that are currently at or near full structural capacity can be upgraded or augmented to meet future leasing demand with relatively minor capital investment by strengthening its foundation, increasing its height or reinforcing the steel crossbars. In the United States, a portion of these upgrade and augmentation costs are generally shared with the customer, resulting in a short payback period for our net capital investment.foreign currency exchange rates.”

Broadcast Communications Towers, DAS Networks and Rooftop Management.In addition to our wireless communications towers, we also own and operate broadcast towers and DAS networks, and provide communications site management services to third parties.

networks, our customer agreements for our outdoor DAS networks typically have an initial non-cancelable term of at least ten years.

For the years ended December 31, 2009, 2008 and 2007, approximately 1% of our rental and management segment revenue was attributable to our DAS networks.

Network Development Services Segment

WeThrough our network development services segment, we offer tower-related services domestically, including site acquisition, zoning and permitting services and structural analysis services, throughwhich primarily support our network development services segment.site leasing business and the addition of new tenants and equipment on our sites. This segment accounted for approximately 3%2%, 3% and 2%3% of our total revenues for the years ended December 31, 2010, 2009 2008 and 2007,2008, respectively.

Site Acquisition, Zoning and Permitting Services. We engage in site acquisition services on our own behalf in connection with our tower development projects, as well as on the behalf of our customers.tenants. We typically work with our customers’

tenants’ engineers to determine the geographic areas where a new tower sitesites will best address the customers’tenants’ needs and meet their coverage objectives. Once a new site is identified, we acquire the rights to the land or structure on which the site will be constructed, and we manage the permitting process to ensure all necessary approvals are obtained to construct and operate the communications site under applicable law.

Structural Analysis.We offer structural analysis services to wireless carriers in connection with the installation of their communications equipment on our towers. Our team of engineers can evaluate whether a tower can support the additional burden of the new equipment or if augmentationan upgrade is needed, which enables our customerstenants to better assess potential sites before making an installation decision. Our structural analysis capabilities enable us to provide higher quality service to our existing customerstenants by, among other things, reducing cycle times, related to tower structural analysis, as well as provide opportunities to offer structural analysis services to third parties.

Strategy

Operational Strategy

Our operational strategy is to capitalize on the growth in the use of wireless communications services and the evolution of advanced wireless handsets, as well as the expanding infrastructure required to deploy current and future generations of wireless communications technologies. To achieve this, our primary focus is to increase the leasing of our existing communications site portfolio, invest in and selectively grow our communications site portfolio, further improve upon our operational performance and maintain a strong balance sheet. We believe these efforts will further support and maximize our ability to capitalize on the growth in demand for wireless infrastructure.

Capital Allocation Strategy

The objective of our capital allocation strategy is to simultaneously increase recurring free cash flow per share growth and our return on invested capital. To achieve this, we expect we will continue to deploy our capital through our annual capital expenditure program and acquisitions, while continuing our stock repurchase program or implementing a dividend program to the extent we determine it necessary or appropriate. During 2010, we generated approximately $1.0 billion of cash provided by operating activities, which along with incremental debt, was used to fund nearly $1.7 billion of investments, which included approximately $346.7 million of capital expenditures, $899.6 million of acquisitions and $420.8 million of stock repurchases, including commissions and fees.

International Expansion Strategy

We believe that in certain international markets, we can create substantial value by establishing an independent wireless infrastructure leasing business. Therefore, we expect we will continue to seek international expansion opportunities, where our risk adjusted return objectives can be achieved. Our international expansion strategy includes a disciplined, individualized market evaluation, whereby we conduct the following analyses:

Demand Drivers

Our strategy is predicated on our belief that wireless service providers will continue to invest in their networks in both our domestic and international markets, driving demand for our communications sites:

As these factors continue to grow as a competitive necessity in the United States on a widespread basis, wireless service providers may be compelled to deploy new technology and equipment, further increase the cell density of their existing networks and expand their network coverage.

We believe demand for our communications sites will continue as wireless service providers seek to increase the quality and coverage of their networks, while also investing in next generation data networks. To meet this demand, we believe wireless carriers will continue to outsource their communications site infrastructure needs as a means to accelerate access to their markets and more efficiently use their capital, rather than construct and operate their own communications sites and maintain their own communications site service and development capabilities.

Recent Developments

Growth and Expansion

In 2009,2010, we continued to focus on our strategy of growing our operations using selective criteria for acquisitions and new site development, including expansion into new and existing international geographic areas. During the year ended December 31, 2009,2010, we grew our communications site portfolio through acquisitions and construction activities, including the acquisition and construction of 3,529approximately 7,800 towers and the installation of 20approximately 30 in-building and one outdoor DAS networks. In addition, we continue to evaluate complementary product lines such as shared generators to supplement our tower site growth and expansion strategy. We also continue to evaluate opportunities to acquire larger communications site portfolios that we believe we can effectively integrate into our portfolio.

United States. During 2009,2010, in response to the needs of our customers,tenants, we pursued the acquisition and construction of communications sites in select locations throughout the United States. Our expansion in the United States during 20092010 included the acquisition and construction of 507approximately 900 towers and the installation of 21approximately 30 in-building and outdoor DAS networks.

Latin AmericaInternational. During 2009, the majority of2010, we increased our expansion effortsfootprint in Latin America were focused in Brazil as our customers sought to increase the density of their networks following a recent wireless spectrum auction. Our expansion in Latin America during 2009 includedprimarily through the acquisition and construction of 578 towers.

Asia.approximately 1,700 towers in Brazil, Chile, Colombia, Mexico and Peru. During 2009,2010, we also expanded our presence and increased our footprint in India through the acquisitionsacquisition of XCELEssar Telecom Infrastructure Private Limited (“XCEL”ETIPL”), adding over 4,600 towers to our communications site portfolio. We also constructed approximately 500 towers in India. As previously disclosed, in 2010 we entered into definitive agreements to acquire communications sites in Brazil, Chile, Colombia, Ghana and Insight Infrastructure Pte. Ltd. (“Insight”), as well as the construction of new communications sites. In 2009, we acquired and constructed 2,444 towers.South Africa, subject to customary closing conditions.

Financing Transactions

During the year ended December 31, 2009,In 2010, we improved our financial position by raisingcontinued to raise capital to refinance and repurchase a portion of our outstanding indebtedness which increased our flexibility and our ability to return value to our stockholders. Significant transactions included those set forth below.

Senior Notes Offerings.fund acquisitions. In JuneAugust and OctoberDecember of 2009,2010, we completed institutional private placementsregistered public offerings of $300.0$700.0 million aggregate principal amount of our 7.25%5.05% senior unsecured notes due 20192020 (“7.25%5.05% Notes”) and $600.0 million$1.0 billion aggregate principal amount of our 4.625% senior unsecured notes due 2015 (“4.625% Notes”), respectively. We used the net proceeds from the offering of the 7.25% Notes to finance the repurchase and redemption of our outstanding 7.50%4.50% senior notes due 20122018 (“7.50% Notes”) and to repay certain of our indebtedness incurred under our $1.25 billion senior unsecured revolving credit facility (“Revolving Credit Facility”). We used the net proceeds from the offering of the 4.625% Notes primarily to finance the redemption of our outstanding 7.125% senior notes due 2012 (“7.125%4.50% Notes”).

Repurchases and Redemption of Debt Securities. During the year ended December 31, 2009, we repurchased or redeemed approximately $725.1 million face amount of our outstanding debt securities, including the repurchase and redemption of $225.0 million principal amount of our 7.50% Notes, the redemption of $500.0 million principal amount of our 7.125% Notes and the redemption of $0.1 million principal amount of our 3.00% convertible notes due August 15, 2012 (“3.00% Notes”).

Stock Repurchase Program.In 2009, we continued to repurchase shares of our Class A common stock (“Common Stock”) pursuant to our publicly announced stock repurchase program. In February 2008, our Board of Directors approved a stock repurchase program, pursuant to which we are authorized to purchase up to $1.5 billion of our Common Stock (“2008 Buyback”). During the year ended December 31, 2009, we repurchased 6.6 million shares of our Common Stock for an aggregate of $214.7 million, including commissions and fees, pursuant to the 2008 Buyback.

For more information about our financing transactions, see Item 7 of this Annual Report under the caption “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources” and notes 6 and 13 to our consolidated financial statements included in this Annual Report.

Regulatory Matters

Towers and Antennas.The Federal Communications Commission (“FCC”) Our domestic and international tower operations are subject to national, state and local regulatory requirements with respect to the Federal Aviation Administration (“FAA”) regulate theregistration, siting, lighting, marking and maintenance of our towers. DependingIn the United States, which accounted for approximately 81% of our total rental and management revenue for the year ended December 31, 2010, depending on factors such as tower height and proximity to public airfields, the construction of new towers or modifications to existing towers may require pre-approval by the FAA. Prior to use, towersFederal Communications Commission (“FCC”) and the Federal Aviation Administration (“FAA”). Towers requiring FAA approvalpre-approval must be registered with the FCC and must be painted, lighted and lightedmaintained in accordance with FAA standards. Similar requirements regarding pre-approval of the FAA’s standards. Tower ownersconstruction and modification of towers are responsible for notifyingimposed by regulators in other countries, such as the FAAMinistry of any tower lighting outages or malfunctionsCivil Aviation in India and for timely repairing lighting outages or malfunctions. Tower owners also must notify the FCC when ownershipMinistry of a tower changes. We generally indemnify our customers against non-compliance with applicable standards.Transportation and Telecommunications in Chile. Non-compliance with applicable tower-related requirements may lead to monetary penalties.

Furthermore, in India, each of our subsidiaries holds an Infrastructure Provider Category-I license (“IP-I”) issued by the Indian Ministry of Communications and Information Technology, which permits us to provide tower space to companies licensed as telecommunications service providers under the Indian Telegraph Act of 1885. While we are required to provide tower space on a non-discriminatory basis, we may negotiate mutually agreeable terms and conditions with such service providers. As a condition to the IP-I, the Indian government has the right to take over our infrastructure in the case of emergency or war.

In all countries in whichwhere we own or operate, towers, we are subject to local zoning restrictions and restrictive covenants imposed by local authorities or community developers. These regulations vary greatly, but typically require tower owners and/or licenseesour tenants to obtain approval from local officials, government agenciesauthorities or

community standards organizations prior to tower construction or the addition of a new antenna to an existing tower. Local zoning authorities and community residents often oppose construction in their communities, which can delay or prevent new tower construction, new antenna installation or site upgrade projects, thereby limiting our ability to respond to customer demand. In addition, zoning regulations can increase costs associated with new tower construction and the addition of new

antennas to a site. Existing regulatory policies may adversely affect the associated timing or cost of such projects and additional regulations may be adopted that cause delays or result in additional costs to us. These factors could materially and adversely affect our construction activities and operations. In the United States, however, the Telecommunications Act of 1996 limits state and local zoning authorities’ jurisdiction over the construction, modification and placement of wireless communications towers. The law preserves local zoning authority but prohibitsauthorities by prohibiting any action that would discriminate between different providers of wireless services or ban altogether the construction, modification or placement of communications towers. It also prohibits state or local restrictions based on the environmental effects of radio frequency emissions to the extent the facilities comply with FCC regulations. The Telecommunications Act of 1996 also requires the federal government to help licensees of wireless communications services gain access to preferred sites for their facilities. This may require that federal agencies and departments work directly with licensees to make federal property available for towers.

Local zoning authorities and community residents often are opposed to construction in their communities, which can delay or prevent new tower construction, new antenna installation or site upgrade projects, thereby limiting our ability to respond to customer demand. In addition, zoning regulations can increase costs associated with new tower construction and the addition of new antennas to a site. Existing regulatory policies may adversely affect the associated timing or cost of such projects and additional regulations may be adopted which can increase delays or result in additional costs to us. These factors could materially and adversely affect our tenants, both domestic and international, construction activities and operations.

As we expand our operations into additional international geographic areas, we will be subject to regulations in these jurisdictions. In addition, our customers in each country may also be subject to new regulatory policies from time to time that may materially and adversely affect the demand for communications sites and in some cases require relocation of certain sites.

Environmental Health and Safety Matters.Our domestic and international operations, like those of other companies engaged in similar businesses, are subject to various environmentalnational, state and occupational health and safetylocal environmental laws and regulations, at all levels of government, including those relating to the management, use, storage, disposal, emission and remediation of, and exposure to, hazardous and non-hazardous substances, materials, and wastes, and the siting of our towers. For example, in India, we are subject to the pollution control laws for the use of diesel generators at sites, and these laws vary from state to state. In the United States, the FCC considers the construction of a new tower or the addition of a new antenna to an existing site (including building rooftops and water towers) to be a federal undertaking subject to prior environmental review and approval under the National Environmental Policy Act of 1969 (“NEPA”), which obligates federal agencies to evaluate the environmental impacts of undertakings to determine whether they may significantly affect the environment. The FCC has issued regulations implementing NEPA as well as the National Historic Preservation Act of 1966 and the Endangered Species Act of 1973. These regulations obligate each FCC applicant or licensee to investigate potential environmental and other effects of operations and to disclose any significant impacts in an environmental assessment prior to constructing a tower or adding a new antenna to a site. If a tower or new antenna would have a significant impact on the environment, FCC approval of the tower or antenna could be significantly delayed.

As an owner, lessee and/or operator of real property and facilities, we may have liability under environmental laws for the costs of investigation, removal or remediation of soil and groundwater contaminated by hazardous substances or wastes at our sites or at sites to which we transported hazardous substances or wastes.waste. Certain of these laws impose cleanup responsibility and liability without regard to whether we, as the owner, lessee or operator, knew of, or were responsible for, the contamination, and whether or not we have discontinued operations or sold the property. We may also be subject to common law claims by third parties based on damages and costs resulting from off-site migration of contamination.

Our domestic and international operations are also subject to guidelines regarding employee protection from radio frequency exposure and other occupational health and safety matters. In the United States, we are subject to the Occupational Safety and Health Act of 1970 and our field personnel are subject to regulation by the

Occupational Safety and Health Administration (“OSHA”) and equivalent state agencies concerning such matters.

We, and our customers, may be required to obtain permits, pay additional property taxes, comply with regulatory requirements, and make certain informational filings related to hazardous substances and devices used to provide power such as batteries, generators and fuel at our sites. Violations of these types of regulations could subject us to fines and/or criminal sanctions.

Additionally, in the United States, before constructing a new tower or adding a new antenna to an existing site, we must review and evaluate the impact of the action to determine whether it may significantly affect the environment and we must disclose any significant impacts in an environmental assessment. If a tower or new antenna might have a material adverse impact on the environment, FCC approval of the tower or antenna could be significantly delayed.

Health and Safety. In the United States and in other countries where we operate, we are subject to various national, state and local laws regarding employee health and safety, including protection from radio frequency exposure.

Competition and Customer Demand

Rental and Management SegmentSegments

Our rental and management segment competessegments compete with other international, national and regional tower companies, such asprimarily Crown Castle International Corp. and SBA Communications Corporation in the United States and Indus Towers in India, as well as wireless carriers and broadcasters that own and operate their own communications site networks and lease space to third parties, numerous independent tower owners and the owners of non-communications sites, including rooftops, utility towers, water towers and other alternative structures. We believe that site location and capacity, network density, price and quality of service have been and will continue to be significant competitive factors affecting owners, operators and managers of communications sites.

Customer demand is also affected by the emergence and growth of new technologies. Technologies that make it possible for wireless carriers to increase the capacity and efficiency of their existing networks could reduce customer demand for our communications sites. The increased use of spectrally efficient air-linkair access technologies, which potentially can relieve some network capacity problems, could reduce the demand for tower-based antenna space. Additionally, certain complementary network technologies, such as femtocells, could offload a portion of network traffic away from the traditional tower-based networks, which could reduce the need for carriers to add more equipment at certain communications sites.

In addition, any increase in the use of network sharing, roaming or resale arrangements by wireless service providers also could adversely affect customer demand for leasing tower space. These arrangements, which are essentially extensions of traditional roaming agreements, enable a provider to adequately serve its customerstenants outside its license area, to give licensed providers the right to enter into arrangements to serve overlapping license areas, and to permit non-licensed providers to enter the wireless marketplace. Consolidation among wireless carriers could have a similarsimilarly impact on customer demand for our communications sites, because the existing networks of wireless carriers often overlap. In addition, if wireless carriers share their sites or swap their sites with other carriers to a significant degree, it could reduce demand for our communications sites.

Network Development Services Segment

Our network development services segment competes with a variety of companies offering individual, or combinations of, competing services. The field of competitors includes site acquisition consultants, zoning consultants, real estate firms, right-of-way consulting firms, structural engineering firms, tower owners/managers, telecommunications equipment vendors who can provide turnkey site development services through multiple subcontractors, and our customers’ internal staffs. We believe that our customers base their decisions for network development services on various criteria, including a company’s experience, local reputation, price, and time for completion of a project.

We believe that we compete favorably as to the key competitive factors relating to our domestic and international rental and management and network development services segments.

Employees

As of December 31, 2009,2010, we employed 1,4201,729 full-time individuals and consider our employee relations to be satisfactory.

Available Information

Our Internet website address iswww.americantower.com. Information contained on our website is not incorporated by reference into this Annual Report, and you should not consider information contained on our website as part of this Annual Report. You may access, free of charge, our Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q, and Current Reports on Form 8-K, plus amendments to such reports as filed or furnished pursuant to SectionSections 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended (“Exchange Act”), through the Investors portion of our website as soon as reasonably practicable after we electronically file such material with, or furnish it to, the Securities and Exchange Commission (“SEC”).

We have adopted a written Code of Conduct that applies to all of our employees and directors, including, but not limited to, our principal executive officer, principal financial officer, and principal accounting officer or controller, or persons performing similar functions. The Code of Conduct, our corporate governance guidelines, and the charters of the audit, compensation, and nominating and corporate governance committees of our Board of Directors are available at the “Investors” portion of our website. In the event we amend the provisions of our Code of Conduct, or provide any waivers ofunder the Code of Conduct for our directors or executive officers, we intend to disclose these events on our website as required by the regulations of the New York Stock Exchange and applicable law.

In addition, paper copies of these documents may be obtained free of charge by writing us at the following address: 116 Huntington Avenue, Boston, Massachusetts 02116, Attention: Investor Relations; or by calling us at (617) 375-7500.

Decrease in demand for our communications sites would materially and adversely affect our operating results and we cannot control that demand.

Many of the factors affecting the demand for our communications sites, and to a lesser extent our network development services, could materially and adversely affect our operating results. Those factors include:

TheAny downturn in the economy or disruption in the financial and credit markets could impact consumer demand for wireless services. If wireless service subscribers significantly reduce their minutes of use, or fail to widely adopt and use wireless data applications, our wireless service provider tenants could experience a decrease in demand for their services. As a result, they may scale back their business plans or otherwise reduce their spending, which could materially and adversely affect leasing demand for our communications sites and our network development services business, which could have a material adverse effect on our business, results of operations and financial condition.

Furthermore, the demand for broadcast space is dependentin the United States and Mexico depends on the needs of television and radio broadcasters. Among other things, technological advances, including the development of satellite-delivered radio and video services, may reduce the need for tower-based broadcast transmission. In addition, as we continue to work with our customers during the transition from analog-based transmissions to digital-based transmissions, any significant increase in attrition rate or decrease in overall demand for broadcast space could have a material adverse effect on our business, results of operations and financial condition.

Furthermore, any downturn in the economy or disruption in the financial and credit markets could have an impact on consumer demand for wireless services. If wireless service subscribers significantly reduce their minutes of use, or fail to widely adopt and use wireless data applications, our wireless carrier customers could experience a decrease in demand for their services. As a result, they may scale back their business plans or otherwise reduce their spending, which could materially and adversely affect demand for our communications sites and our network development services business, which could have a material adverse effect on our business, results of operations and financial condition.

If our wireless service provider customerstenants consolidate or merge with each other to a significant degree, our growth, revenue and ability to generate positive cash flows could be materially and adversely affected.

Significant consolidation among our wireless service provider customerstenants may result in the decommissioning of certain existing communications sites, because certain portions of theirthese tenants’ networks may be redundant, and a reduction in future capital expenditures in the aggregate, because theirthese tenants’ expansion plans may be similar. For example, in connection with the combinations of Verizon Wireless and ALLTEL (to form Verizon Wireless), Cingular and AT&T Wireless (to form AT&T Mobility) and Sprint PCS and Nextel (to form Sprint Nextel) in the United States, and of Iusacell Celular and Unefon (now under the common ownership of Grupo Iusacell) in Mexico, the combined companies either rationalized or have announced plans to rationalize duplicative parts of their networks, which has led tomay result in the decommissioning of certain equipment on our communications sites. We would expect a similar outcome in India if the anticipated consolidation of certain tenants occurs. In addition,

certain combined companies have undergone or are currently undergoing a modernization of their networks, and these and other customerstenants could determine not to renew leases with us as a result. Our future results may be negatively impacted if a significant number of these contractsleases are terminated, and our ongoing contractual revenues would be reduced as a result. Similar consequences might occur if wireless service providers engage in extensive sharing, roaming or resale arrangements as an alternative to leasing on our communications sites.

New technologies or changes in a tenant’s business model could make our tower leasing business less desirable and result in decreasing revenues.

The development and implementation of new technologies designed to enhance the efficiency of wireless networks or changes in a tenant’s business model could reduce the need for tower-based wireless services, have the effect of decreasing demand for tower space, or reduce obtainable lease rates. Examples of such technologies include spectrally efficient air access technologies which potentially can relieve some network capacity problems and could reduce the demand for tower-based antenna space. Additionally, certain complementary network technologies, such as femtocells, could offload a portion of network traffic away from the traditional tower-based networks, which would reduce the need for carriers to add more equipment at certain communications sites. Moreover, the emergence of alternative technologies could reduce the need for tower-based broadcast services transmission and reception. For example, the growth in delivery of wireless communication, radio and video services by direct broadcast satellites could materially and adversely affect demand for our antenna space. The development and implementation of any of these and similar technologies to any significant degree or changes in a tenant’s business model could have a material adverse effect on our business, results of operations and financial condition.

Our expansion initiatives may disrupt our operations or expose us to additional risk if we are not able to successfully integrate operations, assets and personnel.

As we continue to acquire communications sites in our existing markets and expand into new markets, we are subject to a number of risks and uncertainties, including not meeting our return on investment criteria and financial objectives, increased costs, assumed liabilities and the diversion of managerial attention due to acquisitions. Achieving the benefits of acquisitions depends in part on integrating operations, communications tower portfolios and personnel in a timely and efficient manner. Integration may be difficult and unpredictable for many reasons, including, among other things, differing systems and processes, potential cultural differences, and conflicting policies, procedures and operations. In addition, the integration of businesses may significantly burden management and our internal resources.

Furthermore, our international expansion initiatives are subject to additional risks such as complex laws, regulations and business practices that may require additional resources and personnel, as well as those risks described below in “—Our foreign operations are subject to economic, political and other risks that could materially and adversely affect our revenues or financial position, including risks associated with fluctuations in foreign currency exchange rates.” Although we generally focus our international efforts in countries with relatively stable political and macroeconomic environments, we are subject to several factors outside our control, and our expansion initiatives may not succeed and may materially and adversely affect our business, results of operations and financial condition.

We could suffer adverse tax or other financial consequences if taxing authorities do not agree with our tax positions.

We are periodically subject to a number of tax examinations by taxing authorities in the states and countries where we do business, and we expect that we will continue to be subject to tax examinations in the future. In addition, U.S. federal, state and local, as well as international, tax laws and regulations are extremely complex and subject to varying interpretations. We recognize tax benefits of uncertain tax positions when we believe the positions are more likely than not of being sustained upon a challenge by the relevant tax authority. We believe

our judgments in this area are reasonable and correct, but there is no guarantee that our tax positions will not be challenged by relevant tax authorities or that we would be successful in any such challenge. If there are tax benefits that are challenged successfully by a taxing authority, we may be required to pay additional taxes or we may seek to enter into settlements with the taxing authorities, which could require significant payments or otherwise have a material adverse effect on our business, results of operations and financial condition.

If we are unable to utilize our net operating losses, we may be required to make significant payments or adjustments.

We have significant deferred tax assets related to our net operating losses (“NOLs”) in U.S. federal and state taxing jurisdictions. Generally, for U.S. federal and state tax purposes, NOLs can be carried forward and used for up to twenty years, and the tax years will remain subject to examination until three years after the applicable NOLs are used or expire. We may be limited in our ability to utilize NOLs obtained through acquisitions.

To the extent we believe that a NOL is not more likely than not to be utilized, we establish a valuation allowance against the deferred tax asset related to the NOL. Our ability to utilize our NOLs is dependent upon us having sufficient future earnings to utilize our NOLs before they expire. If market conditions change materially and we determine that we will be unable to generate sufficient taxable income in the future to utilize our NOLs, we could be required to record an additional valuation allowance. We review our valuation allowances for our NOLs periodically and make adjustments as needed, which can result in an increase or decrease to the net deferred tax asset related to our NOLs. Our NOLs are also subject to review and potential disallowance upon audit by the taxing authorities of the jurisdictions where the NOLs were incurred, and future changes in tax laws or interpretations of such tax laws could materially limit our ability to utilize our NOLs. If we are unable to use our NOLs or the use of our NOLs is limited, we may have to make significant payments or otherwise record charges or reduce our deferred tax assets, which could have a material adverse effect on our business, results of operations and financial condition.

As we review our tax strategy and assess the utilization of our federal and state NOLs, we are actively considering an election to a REIT for U.S. federal and, where applicable, state income tax purposes. We may make the determination to elect REIT status for the taxable year beginning January 1, 2012, as early as the second half of 2011, subject to the approval of our board of directors, although there is no certainty as to the timing of a REIT election or whether we will make a REIT election at all. If we elect REIT status and we fail to qualify as a REIT for any tax year after such election is effective (and certain relief provisions are not available to us), or we choose not to do so or revoke or otherwise terminate such election, we would be taxed as a regular corporation and may be subject to a higher cash tax burden, which could have a material adverse effect on our business, results of operations and financial condition.

Due to the long-term expectations of revenue growth from tenant leases, we are sensitive to changes in the creditworthiness and financial strength of our tenants.

Due to the long-term nature of our tenant leases, we, like others in the tower industry, depend on the continued financial strength of our tenants. Many wireless service providers operate with substantial leverage. In the past, we have had tenants that have filed for bankruptcy, although to date these bankruptcies have not had a material adverse effect on our business or revenues. In addition, many of our tenants and potential tenants rely on capital raising activities to fund their operations and capital expenditures, and the downturn in the economy and the disruptions in the financial and credit markets have periodically made it more difficult and more expensive to raise capital. If our tenants or potential tenants are unable to raise adequate capital to fund their business plans, they may reduce their spending, which could materially and adversely affect demand for our communications sites and our network development services business. If, as a result of a prolonged economic downturn or otherwise, one or more of our significant tenants experienced financial difficulties or filed for bankruptcy, it could result in uncollectible accounts receivable and an impairment on our deferred rent asset, tower asset, network location intangible asset, customer relationship intangible asset or customer base intangible asset. In addition, it could result in the loss of significant tenants and all or a portion of our anticipated lease revenues

from certain tenants, all of which could have a material adverse effect on our business, results of operations and financial condition. For example, as discussed below in “—Risk Factors—A substantial portion of our revenue is derived from a small number of customers,” Iusacell has been engaged in a refinancing of a majority of its U.S. Dollar denominated debt.

Our foreign operations are subject to economic, political and other risks that could materially and adversely affect our revenues or financial position, including risks associated with fluctuations in foreign currency exchange rates.

Our international business operations and our expansion into new markets in the future could result in adverse financial consequences and operational problems not typically experienced in the United States. For the year ended December 31, 2010, approximately 19% of our consolidated revenue was generated by our international operations. We anticipate that our revenues from our international operations will grow in the future. Accordingly, our business is subject to risks associated with doing business internationally, including:

In our international operations, many of our tenants are subsidiaries of global telecommunications companies. These subsidiaries may not have the explicit or implied financial support of their parent entities.

In addition, we face risks associated with changes in foreign currency exchange rates, including those arising from our operations, investments and financing transactions related to our international business. Volatility in foreign currency exchange rates can also affect our ability to plan, forecast and budget for our international operations and expansion efforts. Our revenues earned from our international operations are primarily denominated in the respective local currencies. We have not historically engaged in significant currency hedging activities relating to our non-U.S. Dollar operations, and a weakening of these foreign currencies against the U.S. Dollar would have a negative impact on our reported revenues and operating profits, which could have a material adverse effect on our business, results of operations and financial condition.

We anticipate that we may need additional financing to fund future growth and expansion initiatives, to refinance our existing indebtedness and to fund our stock repurchase program.

In order to fund future growth and expansion initiatives, refinance our existing indebtedness and fund our stock repurchase program, we may need to raise additional capital through financing activities. We believe our cash provided by operations for the year ending December 31, 2011 will sufficiently fund our cash needs for operations, capital expenditures and cash debt service (interest and principal repayments) obligations for 2011. However, we anticipate that we may need to obtain additional sources of capital in the future to fund growth initiatives and to support additional return of capital to stockholders. If so, depending on market conditions, we may seek to raise capital through credit facilities or debt or equity offerings. Additionally, a downgrade of our credit rating below investment grade could negatively impact our ability to access credit markets or preclude us

from obtaining funds on investment grade terms and conditions. Further, certain of our current debt instruments limit the amount of indebtedness we and our subsidiaries may incur. Additional financing, therefore, may be unavailable, more expensive or restricted by the terms of our outstanding indebtedness. If we are unable to raise capital when our needs arise, we may not be able to fund our future growth and expansion initiatives, refinance our existing indebtedness or fund our stock repurchase program.

A substantial portion of our revenue is derived from a small number of customers.

A substantial portion of our total operating revenues is derived from a small number of customers. For the year ended December 31, 2010, four customers accounted for approximately 74% of our domestic rental and management segment revenue; and four customers accounted for approximately 58% of our international rental and management segment revenue. If any of these customers is unwilling or unable to perform its obligations under our agreements with it, our revenues, results of operations, financial condition and liquidity could be materially and adversely affected. In the ordinary course of our business, we do occasionally experience disputes with our customers, generally regarding the interpretation of terms in our leases. Although we have historically resolved these disputes in a manner that did not have a material adverse effect on us or our customer relationships, it is possible that such disputes could lead to a termination of our leases with customers or a material modification of the terms of those leases, either of which could have a material adverse effect on our business, results of operations and financial condition. If we are forced to resolve any of these disputes through litigation, our relationship with the applicable customer could be terminated or damaged, which could lead to decreased revenues or increased costs, resulting in a corresponding adverse effect on our business, results of operations and financial condition.

Our largest international customer is Iusacell, which is the brand name under which a group of companies controlled by Grupo Iusacell, S.A. de C.V. (“Grupo Iusacell”) operates. Iusacell represented approximately 4% of our total revenue for the year ended December 31, 2010. Grupo Iusacell has been engaged in a refinancing of a majority of its U.S. Dollar denominated debt, and in connection with this process, two of the legal entities of the group, including Grupo Iusacell, voluntarily filed for a pre-packaged Concurso Mercantil (a process substantially equivalent to Chapter 11 of U.S. Bankruptcy Law) with the backing of a majority of their financial creditors in December 2010. As of December 31, 2010, Iusacell notes receivable, net, and related assets (which include financing lease commitments and a deferred rent asset that are primarily long-term in nature) were $19.7 million and $51.2 million, respectively. If Grupo Iusacell is unable to restructure its U.S. Dollar denominated debt, it may not be able to meet its operating obligations, including making payments to us in the future, which could have a material adverse effect on our business and results of operations.

Increasing competition in the tower industry may create pricing pressures that may materially and adversely affect us.

Our industry is highly competitive, and our tenants have numerous alternatives for leasing antenna space. Some of our competitors, such as wireless carriers that allow collocation on their towers, are larger and may have greater financial resources than we do, while other competitors may have lower return on investment criteria than we do.

Competitive pricing pressures for tenants on towers from these competitors could materially and adversely affect our lease rates and services income. In addition, we may not be able to renew existing tenant leases or enter into new tenant leases, resulting in a material adverse impact on our results of operations and growth rate. Increasing competition could also make the acquisition of high quality tower assets more costly. Any of these factors could materially and adversely affect our business, results of operations or financial condition.

Our business is subject to government regulations and changes in current or future laws or regulations could restrict our ability to operate our business as we currently do.

Our business, and that of our tenants, is subject to federal, state, local and foreign regulation. In certain jurisdictions these regulations could be applied or enforced retroactively. Local zoning authorities and

community organizations are often opposed to construction in their communities and these regulations can delay, prevent or increase the cost of new tower construction, modifications, additions of new antennas to a site, or site upgrades, thereby limiting our ability to respond to customer demands and requirements. Existing regulatory policies may materially and adversely affect the associated timing or cost of such projects and additional regulations may be adopted which increase delays or result in additional costs to us, or that prevent such projects in certain locations. These factors could materially and adversely affect our business, results of operations and financial condition. For more information regarding the regulations we are subject to, please see Item 1 of this Annual Report under the caption “Regulatory Matters.”

If we are unable or choose not to exercise our rights to purchase towers that are subject to lease and sublease agreements at the end of the applicable period, our cash flows derived from such towers would be eliminated.

As discussed in note 16 to our consolidated financial statements included in this Annual Report, our communications site portfolio includes towers that we operate pursuant to lease and sublease agreements that include a purchase option at the end of each lease period. We may not have the required available capital to exercise our right to purchase leased or subleased towers at the end of the applicable period. Even if we do have available capital, we may choose not to exercise our right to purchase such towers for business or other reasons. In the event that we do not exercise these purchase rights, or are otherwise unable to acquire an interest that would allow us to continue to operate these towers after the applicable period, we will lose the cash flows derived from such towers, which may have a material adverse effect on our business. In the event that we decide to exercise these purchase rights, the benefits of the acquisitions of such towers may not exceed the associated acquisition, compliance and integration costs, and our business, results of operations or financial condition could be materially and adversely affected.

If we are unable to protect our rights to the land under our towers, it could adversely affect our business and operating results.

Our real property interests relating to our towers consist primarily of leasehold and sub-leasehold interests, fee interests, easements, licenses and rights-of-way. A loss of these interests at a particular tower site may interfere with our ability to operate a tower and generate revenues. Approximately 85% of the communications sites in our portfolio as of December 31, 2010 are located on land we lease, but do not own. Approximately 86% of the ground leases for these sites have a final expiration date of 2020 and beyond. Our inability to protect our rights to the land under our towers may have a material adverse effect on our business, results of operations or financial condition.

Our leverage and debt service obligations may materially and adversely affect us.

As of December 31, 2009,2010, we had approximately $4.2$5.6 billion of consolidated debt, and the ability to borrow additional amounts of approximately $695.8$917.7 million under the Revolvingour $1.25 billion senior unsecured revolving credit facility (the “Revolving Credit Facility.Facility”). Our substantial level of indebtedness increases the possibility that we may be unable to generate cash sufficient to pay when due the principal of, interest on, or other amounts due with respect to, our indebtedness. We are also permitted, subject to certain restrictions under our existing indebtedness, to draw down on our Revolving Credit Facility, obtain additional long-term debt and working capital lines of credit to meet future financing needs. This would have the effect of increasingincrease our total leverage.

Our leverage could have significant negative consequences on our financial condition and results of operations, including:

Restrictive covenants in the loan agreement related to our Securitization, the loan agreement for the Revolving Credit Facility and term loan,Term Loan and the indentures governing our debt securities and the loan agreement related to our Securitization could materially and adversely affect our business by limiting flexibility.

The loan agreement for the Revolving Credit Facility and the additional $325.0 million of term loan commitments (“Term Loan”) contain restrictive covenants, as well as requirements to comply with certain leverage and other financial maintenance tests, and thus require that we limit our ability to take various actions, including incurring additional debt, guaranteeing indebtedness and engaging in various types of transactions, including mergers, acquisitions and sales of assets. Additionally, our indentures restrict our and our subsidiaries’ ability to incur liens securing our or their indebtedness. These covenants could place us at a disadvantage compared to some of our competitors, who may have fewer restrictive covenants and may not be required to operate under these restrictions. Further, these covenants could have an adverse effect on our business by limiting our ability to take advantage of financing, new tower development, mergers and acquisitions or other opportunities.

The loan agreement related to our Securitization includes operating covenants and other restrictions customary for loans subject to rated securitizations. Among other things, the borrowers under the loan agreement for the Securitization are prohibited from incurring other indebtedness for borrowed money or further encumbering their assets. A failure to comply with the covenants in the loan agreement could prevent the borrowers from taking certain actions with respect to the towers subject to the Securitization, and could prevent the borrowers from distributing any excess cash from the operation of such towers to us. If the borrowers were to default on the loan, the servicer on the loan could seek to foreclose upon or otherwise convert the ownership of the towers subject to the Securitization, in which case we could lose such towers and the revenue associated with such towers.

The loan agreement for the Revolving Credit Facility and the additional $325.0 million of term loan commitments (“Term Loan”) contain restrictive covenants, as well as requirements to comply with certain leverage and other financial maintenance tests, and thus require that we limit our ability to take various actions, including incurring additional debt, guaranteeing indebtedness, paying dividends or other distributions to shareholders, and engaging in various types of transactions, including mergers, acquisitions and sales of assets. Additionally, our indentures restrict our and our subsidiaries’ ability to incur liens securing our or their indebtedness. These covenants could have an adverse effect on our business by limiting our ability to take advantage of financing, new tower development, mergers and acquisitions or other opportunities.

In addition, reporting and information covenants in our loan agreements and indentures require that we provide financial and operating information within certain time periods. If we are unable to timely provide the required information, we would be in breach of these covenants. For more information regarding the covenants and requirements discussed above, please see Item 7 of this Annual Report under the caption “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources—Factors Affecting Sources of Liquidity” and note 6 to our consolidated financial statements included in this Annual Report.

We could suffer adverse tax and other financial consequences if taxing authorities do not agree with our tax positions, or we are unable to utilize our net operating losses.

We are periodically subject to a number of tax examinations by taxing authorities in the states and countries where we do business, and we expect that we will continue to be subject to tax examinations in the future. In addition, U.S. federal, state and local, as well as international, tax laws and regulations are extremely complex and subject to varying interpretations. We recognize tax benefits of uncertain tax positions when we believe the positions are more likely than not of being sustained upon a challenge by the relevant tax authority. We believe our judgments in this area are reasonable and correct, but there is no guarantee that our tax positions will not be challenged by relevant tax authorities or that we would be successful in any such challenge. If there are tax benefits that are challenged successfully by a taxing authority, we may be required to pay additional taxes or we may seek to enter into settlements with the taxing authorities, which could require significant payments or otherwise have a material adverse effect on our business, results of operations and financial condition.

In addition, we have significant deferred tax assets related to our net operating losses (“NOLs”) in U.S. federal and state taxing jurisdictions. Generally, for U.S. federal and state tax purposes, NOLs can be carried forward and used for up to twenty years, and all of our tax years will remain subject to examination until three years after our NOLs are used or expire. We may be limited in our ability to utilize our NOLs to offset future taxable income and thereby reduce our otherwise payable income taxes. We have substantial federal and state NOLs, including significant portions obtained through acquisitions and dispositions, as well as those generated through our historic business operations. In addition, we have disposed of some entities and restructured other entities in conjunction with financing transactions and other business activities.

To the extent we believe that a position with respect to an NOL is not more likely than not to be sustained, we do not record the related deferred tax asset. In addition, for NOLs that meet the recognition threshold, we assess the recoverability of the NOL and establish a valuation allowance against the deferred tax asset related to the NOL if recoverability is questionable. Given the uncertainty surrounding the recoverability of certain of our NOLs, we have established a valuation allowance to offset the related deferred tax asset so as to reflect what we believe to be the recoverable portion of our NOLs.

Our ability to utilize our NOLs is also dependent, in part, upon us having sufficient future earnings to utilize our NOLs before they expire. If market conditions change materially and we determine that we will be unable to generate sufficient taxable income in the future to utilize our NOLs, we could be required to record an additional valuation allowance. We review our uncertain tax position and the valuation allowance for our NOLs periodically and make adjustments from time to time, which can result in an increase or decrease to the net deferred tax asset related to our NOLs. Our NOLs are also subject to review and potential disallowance upon audit by the taxing authorities of the jurisdictions where the NOLs were incurred, and future changes in tax laws or interpretations of such tax laws could limit materially our ability to utilize our NOLs. If we are unable to use our NOLs or use of our NOLs is limited, we may have to make significant payments or otherwise record charges or reduce our deferred tax assets, which could have a material adverse effect on our business, results of operations and financial condition.

Due to the long-term expectations of revenue from tenant leases, we are sensitive to the creditworthiness and financial strength of our tenants.

Due to the long-term nature of our tenant leases, we, like others in the tower industry, are dependent on the continued financial strength of our tenants. Many wireless service providers operate with substantial leverage. In the past, we have had customers that have filed for bankruptcy, although to date these bankruptcies have not had a material adverse effect on our business or revenues. In addition, many of our customers and potential customers rely on capital raising activities to fund their operations and capital expenditures, and the downturn in the economy and the disruptions in the financial and credit markets have made it more difficult and more expensive to raise capital. If our customers or potential customers are unable to raise adequate capital to fund their business plans, they may reduce their spending, which could materially and adversely affect demand for our communications sites and our network development services business. If, as a result of a prolonged economic downturn or otherwise, one or more of our significant customers experienced financial difficulties or filed for bankruptcy, it could result in uncollectible accounts receivable and an impairment on our deferred rent asset, tower asset or customer relationship intangible asset. In addition, it could result in the loss of significant customers and all or a portion of our anticipated lease revenues from certain customers, all of which could have a material adverse effect on our business, results of operations and financial condition. For example, as discussed below in “—Risk Factors—A substantial portion of our revenue is derived from a small number of customers,” Grupo Iusacell suspended the debt service payment of its U.S. Dollar denominated debt to its bondholders and is currently in negotiations with those bondholders. While Grupo Iusacell’s operating subsidiaries have continued to make partial payments to us, our net accounts receivable related to Grupo Iusacell was approximately $28.2 million as of December 31, 2009.

Our foreign operations are subject to economic, political and other risks that could materially and adversely affect our revenues or financial position, including risks associated with foreign currency exchange rates.

Our business operations in Mexico, Brazil and India, and our expansion into any other international geographic areas in the future, could result in adverse financial consequences and operational problems not typically experienced in the United States. For the year ended December 31, 2009, approximately 15% of our consolidated revenues were generated by our international operations. We anticipate that our revenues from our international operations may grow in the future. Accordingly, our business is subject to risks associated with doing business internationally, including:

In addition, we face risks associated with changes in foreign currency exchange rates, including those arising from our operations, investments and financing transactions related to our international business. Volatility in foreign currency exchange rates can also affect our ability to plan, forecast and budget for our international operations and expansion efforts. While most of the contracts for our operations in Mexico are denominated in the U.S. Dollar, many are denominated in the Mexican Peso, and contracts for our operations in Brazil and India are denominated in the local currencies. We have not historically engaged in significant currency hedging activities relating to our non-U.S. Dollar operations, and a weakening of these foreign currencies against the U.S. Dollar would have a negative impact on our reported revenues and operating profits, which could have a material adverse effect on our business, results of operations and financial condition.

A substantial portion of our revenue is derived from a small number of customers.

A substantial portion of our total operating revenues is derived from a small number of customers. For the year ended December 31, 2009:

Our largest international customer is Grupo Iusacell, which now controls both Iusacell Celular and Unefon in Mexico. Grupo Iusacell is under common control with TV Azteca. Grupo Iusacell accounted for approximately 5% of our total revenues for the year ended December 31, 2009. In addition, for the year ended December 31, 2009, we received $15.7 million in interest income from TV Azteca on our net note receivable balance of $108.2 million.

If any of these customers is unwilling or unable to perform its obligations under our agreements with them, our revenues, results of operations, financial condition and liquidity could be materially and adversely affected. In the ordinary course of our business, we do occasionally experience disputes with our customers, generally regarding the interpretation of terms in our agreements. Although we have historically resolved these disputes in a manner that did not have a material adverse effect on us or our customer relationships, it is possible that such disputes could lead to a termination of our agreements with customers or a material modification of the terms of those agreements, either of which could have a material adverse effect on our business, results of operations and financial condition. If we are forced to resolve any of these disputes through litigation, our relationship with the applicable customer could be terminated or damaged, which could lead to decreased revenues or increased costs, resulting in a corresponding adverse effect on our business, results of operations and financial condition.

On April 1, 2009, Grupo Iusacell announced that one of its subsidiaries had suspended the debt service payment of its U.S. Dollar denominated debt as part of an ongoing process to restructure its U.S. Dollar denominated debt, which has been affected by the significant devaluation of the Mexican Peso versus the U.S. Dollar. While Grupo Iusacell has continued to make partial payments to us, our net accounts receivable related to Grupo Iusacell was approximately $28.2 million as of December 31, 2009. We also have approximately $33.5 million of other Grupo Iusacell related assets as of December 31, 2009, which includes financing lease commitments and accrued straight-line revenue that are primarily long-term in nature. If Grupo Iusacell is unable to restructure its indebtedness or if a further devaluation of the Mexican Peso were to adversely impact Grupo Iusacell’s overall liquidity, Grupo Iusacell might not be able to meet its operating obligations, including making full payments under the lease agreements with us in the future, which could have a material adverse effect on our business and results of operations.

We anticipate that we may need additional financing to fund future growth and expansion initiatives, to refinance our existing indebtedness and to fund our stock repurchase program.

In order to fund future growth and expansion initiatives, refinance our existing indebtedness and fund our stock repurchase program, we may need to raise additional capital through financing activities. We believe our cash provided by operations for the year ending December 31, 2010 will be sufficient to fund our cash needs for operations, capital expenditures and cash debt service (interest and principal repayments) obligations for 2010. However, we anticipate that we may need to obtain additional sources of capital in the future to fund growth initiatives and to support additional return of capital to stockholders. If so, depending on market conditions, we may seek to raise capital through credit facilities or debt or equity offerings. A downgrade of our credit rating below investment grade could negatively impact our ability to access credit markets or preclude us from obtaining funds on investment grade terms and conditions. Further, certain of our current debt instruments limit the amount of indebtedness we and our subsidiaries may incur. Additional financing, therefore, may be unavailable, more expensive or restricted by the terms of our outstanding indebtedness. If we are unable to raise capital when our needs arise, we may not be able to fund our stock repurchase program, refinance our existing indebtedness or fund future growth and expansion initiatives.

New technologies could make our tower leasing business less desirable to potential tenants and result in decreasing revenues.

The development and implementation of new technologies designed to enhance the efficiency of wireless networks could reduce the use and need for tower-based wireless services transmission and reception and have

the effect of decreasing demand for tower space. Examples of such technologies include spectrally efficient air-link technologies which potentially can relieve some network capacity problems, could reduce the demand for tower-based antenna space. Additionally, certain complementary network technologies, such as femtocells, could offload a portion of network traffic away from the traditional tower-based networks, which would reduce the need for carriers to add more equipment at certain communications sites. Moreover, the emergence of alternative technologies could reduce the need for tower-based broadcast services transmission and reception. For example, the growth in delivery of wireless communication, radio and video services by direct broadcast satellites could materially and adversely affect demand for our antenna space. The development and implementation of any of these and similar technologies to any significant degree could have a material adverse effect on our business, results of operations and financial condition.

We could have liability under environmental laws.

Our operations, like those of other companies engaged in similar businesses, are subject to the requirements of various federal, state, local and foreign environmental and occupational safety and health laws and regulations, including those relating to the management, use, storage, disposal, emission and remediation of, and exposure to,

hazardous and non-hazardous substances, materials and wastes. As the owner, lessee or operator of real property and facilities, we may be liable for substantial costs of investigation, removal or remediation of soil and groundwater contaminated by hazardous materials, without regard to whether we, as the owner, lessee or operator, knew of, or were responsible for, the contamination. We may also be liable for certain costs of remediating contamination at third party sites to which we sent waste for disposal, even if the original disposal may have accordedcomplied with all legal requirements.requirements at the time. Many of these laws and regulations contain information reporting and record keeping requirements. We cannot assure you that we are at all times in complete compliance with all environmental requirements. We may be subject to potentially significant fines or penalties if we fail to comply with any of these requirements. The requirements of these laws and regulations are complex, change frequently, and could become more stringent in the future. In certain jurisdictions these laws and regulations could be applied or enforced retroactively. It is possible that these requirements will change or that liabilities will arise in the future in a manner that could have a material adverse effect on our business, results of operations and financial condition.

Our business is subject to government regulations and changes in currenttowers or future laws or regulations could restrict our ability to operate our business as we currently do.

Our business, and that of our customers, is subject to federal, state, local and foreign regulation, including by the FAA, the FCC, the U.S. Environmental Protection Agency and the OSHA. Both the FCC and the FAA regulate towers used for wireless communications and radio and television broadcasting and the FCC separately regulates transmitting devices operating on towers. Similar regulations exist in Mexico, Brazil, India and other foreign countries regarding wireless communications and the operation of towers. Local zoning authorities and community organizations are often opposed to construction in their communities and these regulations can delay, prevent or increase the cost of new tower construction, modifications, additions of new antennas to a site, or site upgrades, thereby limiting our ability to respond to customer demands and requirements. Existing regulatory policies may materially and adversely affect the associated timing or cost of such projects and additional regulations may be adopted which increase delays or result in additional costs to us, or that prevent such projects in certain locations. These factors could materially and adversely affect our business, results of operations and financial condition.

Increasing competition in the tower industry may create pricing pressures that may materially and adversely affect us.

Our industry is highly competitive, and our customers have numerous alternatives for leasing antenna space. Some of our competitors, such as national wireless carriers that allow collocation on their towers, are larger and may have greater financial resources than we do, while other competitors may have lower return on investment criteria than we do.

Our competition includes:

Competitive pricing pressures for tenants on towers from these competitors could materially and adversely affect our lease rates and services income. In addition, we may not be able to renew existing customer leases or enter into new customer leases, resulting in a material adverse impact on our results of operations and growth rate. Increasing competition could also make the acquisition of high quality tower assets more costly. Any of these factors could materially and adversely affect our business, results of operations or financial condition.

If we are unable to protect our rights to the land under our towers, it could adversely affect our business and operating results.

Our real property interests relating to our towers consist primarily of leasehold and sub-leasehold interests, fee interests, easements, licenses and rights-of-way. A loss of these interests at a particular tower site may interfere with our ability to operate a tower and generate revenues. For various reasons, we may not always have the ability to access, analyze and verify all information regarding titles and other issues prior to completing an acquisition of communications sites, which can affect our rights to access and operate a site. From time to time we also experience disputes with landowners regarding the terms of ground agreements for land under a tower, which can affect our ability to access and operate a tower site. Further, for various reasons, landowners may not want to renew their ground agreements with us, they may lose their rights to the land, or they may transfer their land interests to third parties, including ground lease aggregators, which could affect our ability to renew ground agreements on commercially viable terms. Approximately 83% of the communications sites in our portfolio as of December 31, 2009 are located on land we do not own. Approximately 89% of the ground agreements for these sites have a final expiration date of 2019 and beyond. Our inability to protect our rights to the land under our towers may have a material adverse effect on our business, results of operations or financial condition.

If we are unable or choose not to exercise our rights to purchase towers that are subject to lease and sublease agreements at the end of the applicable period, our cash flows derived from such towers would be eliminated.

Our communications site portfolio includes towers that we operate pursuant to lease and sublease agreements that include a purchase option at the end of each lease period. If we are unable or choose not to exercise our rights to purchase towers under these agreements at the end of the applicable period, our cash flows derived from such towers would be eliminated. For example, our SpectraSite subsidiary has entered into lease or sublease agreements with affiliates of SBC Communications, a predecessor entity to AT&T Mobility, with respect to approximately 2,500 towers pursuant to which SpectraSite has the option to purchase the sites upon the expiration of the lease or sublease beginning in 2013. The aggregate purchase option price for the AT&T Mobility towers was approximately $413.0 million as of December 31, 2009, and will accrete at a rate of 10% per year to the applicable expiration of the lease or sublease of a site. We have entered into a similar agreement with ALLTEL, which completed its merger with Verizon Wireless in January 2009, with respect to approximately 1,800 towers, for which we have an option to purchase the sites upon the expiration of the lease or sublease beginning in 2016. The aggregate purchase option price for the ALLTEL towers was approximately $63.3 million as of December 31, 2009, and will accrete at a rate of 3% per year through the expiration of the lease or sublease period. At ALLTEL’s option, at the expiration of the sublease period, the purchase price would

be payable in cash or with 769 shares of our Common Stock per tower. We may not have the required available capital to exercise our right to purchase these or other leased or subleased towers at the end of the applicable period. Even if we do have available capital, we may choose not to exercise our right to purchase such towers for business or other reasons. In the event that we do not exercise these purchase rights, or are otherwise unable to acquire an interest that would allow us to continue to operate these towers after the applicable period, we will lose the cash flows derived from such towers, which may have a material adverse effect on our business. In the event that we decide to exercise these purchase rights, the benefits of the acquisitions of such towers may not exceed the associated acquisition, compliance and integration costs, and our business, results of operations or financial condition could be materially and adversely affected.

Our towersdata centers may be affected by natural disasters and other unforeseen damage for which our insurance may not provide adequate coverage.

Our towers are subject to risks associated with natural disasters, such as ice and wind storms, tornadoes, floods, hurricanes and earthquakes, as well as other unforeseen damage. Any damage or destruction to our towers or data centers as a result of these or other risksevents would impact our ability to provide services to our customerstenants and could materially and adversely impact our results of operation or financial condition. While we maintain insurance coverage for natural disasters, we may not have adequate insurance to cover the associated costs of repair or reconstruction for a major future major event. Further, we carry business interruption insurance, but such insurance may not adequately cover all of our lost revenues, including potential revenues from new tenants that could have been added to our towers but for the damage. If we are unable to provide services to our customerstenants as a result of damage to our towers, it could lead to customer loss, resulting in a corresponding material adverse effect on our business, results of operations or financial condition.

Our costs could increase and our revenues could decrease due to perceived health risks from radio emissions, especially if these perceived risks are substantiated.

Public perception of possible health risks associated with cellular and other wireless communications technology could slow the growth of wireless companies, which could in turn slow our growth. In particular, negative public perception of, and regulations regarding, these perceived health risks could slow the market acceptance of wireless communications services and increase opposition to the development and expansion of tower sites. The potential connection between radio frequency emissions and certain negative health effects has been the subject of substantial study by the scientific community in recent years, and numerous health-related lawsuits have been filed against wireless carriers and wireless device manufacturers. If a scientific study or court decision resulted in a finding that radio frequency emissions posedpose health risks to consumers, it could negatively impact the market for wireless services, as well as our wireless carrier customers,tenants, which could materially and adversely affect our business, results of operations or financial condition. We do not maintain any significant insurance with respect to these matters.

Our historical stock option granting practices are subject to ongoing governmental proceedings, which could result in fines, penalties or other liability.

In May 2006, we announced that our Board of Directors had established a special committee of independent directors to conduct a review of our stock option granting practices and related accounting. Subsequent to the formation of the special committee, we received an informal letter of inquiry from the SEC, a subpoena from the office of the United States Attorney for the Eastern District of New York and an information document request from the Internal Revenue Service (“IRS”), each requesting documents and information related to our stock option grants and practices. We also received a request for information from the Department of Labor, which concluded its review in September 2008, with no action taken against us. We have cooperated with these governmental authorities to provide the requested documents and information. These governmental proceedings are ongoing, and the time period necessary to resolve these proceedings is uncertain and could require significant

additional management and financial resources. Significant legal and accounting expenses related to these matters have been incurred to date, and we may incur expenses in the future. Depending on the final outcomes of these proceedings, we and members of our senior management could be subject to regulatory fines, penalties, enforcement actions or other liability, which could have a material adverse impact on our business, results of operations or financial condition. In addition, as a result of the special committee’s findings, we restated our historical financial statements for certain periods prior to March 31, 2006 to, among other things, record changes for stock-based compensation expense (and related tax effects) relating to certain past stock option grants.

None.

Our principal offices are located in Boston, Southborough and Woburn, Massachusetts; Atlanta, Georgia; Cary, North Carolina; Mexico City, Mexico; Sao Paulo, Brazil; and Delhi and Mumbai, India.India; Lima, Peru; and Bogota, Colombia. Details of each of these offices are provided below:

In addition to the principal offices set forth above, we maintain offices in the geographic areas we serve through which we operate our tower leasing and services businesses. We also have anbusinesses, as well as maintain offices to pursue international business development group based in London, England.initiatives. We believe that our owned and leased facilities are suitable and adequate to meet our anticipated needs.

Our interests in our communications sites are comprised of a variety of ownership interests, including leases created by long-term ground lease agreements, easements, licenses or rights-of-way granted by government entities. Pursuant to the loan agreement for our Securitization, the tower sites subject to the Securitization are subject to mortgages, deeds of trust and deeds to secure the loan. A typical tower site consists of a compound

enclosing the tower site, a tower structure, and one or more equipment shelters that house a variety of transmitting, receiving and switching equipment. There are three principal types of towers: guyed, self-supporting lattice, and monopole.

Of the approximately 27,20035,000 communications sites in our portfolio as of December 31, 2009,2010, approximately 83%85% are located on land we lease, but do not own. Ground agreementsleases for land underlying our towers generally have an initial term of five years with three or four additional automatic renewal periods of five years, for a total of twenty to twenty-five years. As a result, approximately 89%86% of the ground agreements for our sites have a final expiration date of 20192020 and beyond.

On May 18,During the year ended December 31, 2006, we received a letter of informal inquiry from the SEC Division of Enforcement requesting documents and other information related to our stock option grants and stock option practices. The inquiry is focused on stock options granted to senior management and members of our Board of Directors during the period 1997 to 2006. We continue to cooperate withOn December 17, 2010, the SEC notified us that it did not intend to provide documents, testimony and other information, as requested. We are aware that in February 2008, a former officer of the Company received a “Wells” notice from the SEC which affords such individual the opportunity to make a submission to the SEC with respect to contemplated civilrecommend any enforcement recommendations against such individual for certain violations of the federal securities laws.

On May 19, 2006, we received a subpoena from the United States Attorney’s Office for the Eastern District of New York for records and information relating to our stock option granting practices. The subpoena requests materials related to certain stock options granted between 1995 and 2006. We continue to cooperate with the U.S. Attorney’s Office to provide the requested information and documents.

On May 26, 2006, a purported securities class action was filed in United States District Court for the District of Massachusetts against us and certain of our current and former officers by John S. Greenebaum for monetary relief. In March 2007, an amended consolidated complaint was filed, naming certain of our current and former officers and directors of the Company as defendants and alleging that the defendants violated federal securities laws in connection with public statements made relating to our stock option practices and related accounting. The complaint asserted claims under Sections 10(b) and 20(a) of the Exchange Act and SEC Rule 10b-5. In February 2008, the court preliminarily approved a settlement we had reached with the plaintiffs. The settlement provided for a payment by us of $14.0 million and led to a dismissal of all claims against all defendants in the litigation. In March and April of 2008, we paid the settlement amount. In May 2008, the original plaintiff, Mr. Greenebaum, filed an objection to the settlement which was dismissed by the court. In June and July of 2008, the court approved the settlement and denied a request by Mr. Greenebaum to opt-out of the settlement class certified by the court. Mr. Greenebaum appealed the decision of the court relating to him and in December 2008, we entered

into a settlement agreement with Mr. Greenebaum providing for payment by us of $5,000, which the court approved in January 2009. In January 2009, the plaintiff’s class entered into a settlement agreement with Mr. Greenebaum. As a result of these settlements, Mr. Greenebaum withdrew his appeals, effectively ending the litigation.

On May 24, 2006 and June 14, 2006, two shareholder derivative lawsuits were filed in Suffolk County Superior Court in Massachusetts by Eric Johnston and Robert L. Garber, respectively. The lawsuits were filed against certain of our current and former officers and directors for alleged breaches of fiduciary duties and unjust enrichment in connection with our historical stock option granting practices. The lawsuits also named us as a nominal defendant. The lawsuits sought to recover the damages sustained by us and disgorgement of all profits received with respect to the alleged backdated stock options. In October 2007, the court dismissed the complaint, without leave to amend, due to the plaintiffs’ failure to make a demand upon our Board of Directors before initiating their lawsuits. In December 2007, the plaintiffs filed an appeal of that decision to the Massachusetts Court of Appeals. In June 2008, the Massachusetts Supreme Judicial Court elected, on its own motion, to hear the appeal, and in April 2009, affirmed the judgment dismissing the complaint without leave to amend. The plaintiffs’ right to initiate a new claim based on the response to the demand made at the time of dismissal expired in July 2009.

On August 31, 2006, we received an Information Document Request from the IRS for documents and information relating to our stock option granting practices and related accounting. The IRS requested materials related to certain stock options granted between 1998 and 2005. We have received subsequent related requests and we continue to cooperate with the IRS to provide the requested information and documents.action.

One of our subsidiaries, SpectraSite Communications, Inc. (“SCI”), is involved in a lawsuit brought in Mexico against a former Mexican subsidiary of SCI (the subsidiary of SCI was sold in 2002, prior to our merger with SCI’s parent in 2005). The lawsuit concerns a terminated tower construction contract and related agreements with a wireless carrier in Mexico. The primary issue for us is whether SCI itself can be found liable to the Mexican carrier. The trial and lower appellate courts initially found that SCI had no such liability in part because Mexican courts do not have fullthe necessary jurisdiction over SCI. TheseFollowing several decisions were appealed by Mexican appellate courts, including the plaintiff,Supreme Court of Mexico, and in July 2008, they were reversedrelated appeals by both parties, an intermediate Mexican appellate court.court issued a new decision that would, if enforceable, reimpose liability on SCI in September 2010. In its decision, the intermediate appellate court identified potential damages of approximately $23.0 million. SCI appealed that ruling to a higher constitutional court in Mexico. In January 2009, the constitutional court ruled in SCI’s favor, remanding the case back to the intermediate appellate court for further proceedings. In March 2009, the intermediate appellate court issued its decision, which reasserts jurisdiction$6.7 million, and reimposes liability on SCI. In April 2009, as permitted under Mexican law, SCI filed an appeal of this decision to the higher constitutional court on the grounds that the decision of the intermediate appellate court is inconsistent with the January 2009 ruling of the higher constitutional court and Mexican law. In August 2009, the plaintiffOctober 14, 2010, we filed a petition with the Supreme Court of Mexico asking the court to rule on SCI’snew constitutional appeal to again dispute the constitutional court. In September 2009, the Supreme Court refused to hear the appeal.decision. As a result, at this stage of the case remains pending in the constitutional court andproceeding, we are unable to determine whether the liability imposed on SCI by the September 2010 decision will survive or to estimate our share, if any, of that potential liability at this stageif the decision survives the pending appeal.

On June 3, 2010, Horse-Shoe Capital (“Horse-Shoe”), a company formed under the laws of the proceedings.Republic of Mauritius, filed a complaint in the Supreme Court of the State of New York, New York County, with respect to Horse-Shoe’s sale of XCEL Telecom Private Limited (“XCEL”) to American Tower Mauritius (“AT Mauritius”), our wholly-owned subsidiary formed under the laws of the Republic of Mauritius. The complaint names AT Mauritius, ATI and us as defendants, and the dispute concerns the timing and amount of distributions to be made by AT Mauritius to Horse-Shoe from a $7.5 million holdback escrow account and a $15.7 million tax escrow account, each established by the transaction agreements at the closing of the transaction. The complaint seeks release of the entire holdback escrow account, plus an additional $2.8 million, as well as the release of approximately $12.0 million of the tax escrow account. The complaint also seeks punitive damages in excess of $69.0 million. We filed an answer to the complaint in August 2010, disputing both the amounts alleged to be owed under the escrow agreements as well as the timing of the escrow distributions. We also asserted in our answer that the demand for punitive damages is meritless. The parties filed cross-motions for summary judgment concerning the release of the tax escrow account and in January 2011, the court granted our motion for summary judgment, finding no obligation for us to release the disputed portion of the tax escrow until 2013. Other claims remain pending. We are vigorously defending the lawsuit.

We periodically become involved in various claims and lawsuits that are incidental to our business. In the opinion of management, after consultation with counsel, other than the legal proceedings discussed above and in note 16 to our consolidated financial statements included in this Annual Report, there are no matters currently pending that would, in the event of an adverse outcome, have a material impact on our consolidated financial position, results of operations or liquidity.

PART II

The following table presents reported quarterly high and low per share sale prices of our Common Stock on the New York Stock Exchange (“NYSE”) for the years 20092010 and 2008.2009.

On February 12, 2010,11, 2011, the closing price of our Common Stock was $42.62$56.73 per share as reported on the NYSE. As of February 12, 2010,11, 2011, we had 402,669,455397,612,895 outstanding shares of Common Stock and 482463 registered holders.

Dividends

We have nevernot historically paid a dividend on our Common Stock. We anticipatePayment of dividends in the future, when, as and if authorized by our board of directors, would depend upon many factors, including our earnings and financial condition, restrictions under applicable law and our current and future loan agreements, our debt service requirements, our capital expenditure requirements and other factors that weour board of directors may retain future earnings, if any,deem relevant from time to fundtime, including the development and growth of our business. Thepotential determination to elect REIT status. In addition, the loan agreement for our Revolving Credit Facility and Term Loan contain covenants that generally restrict our ability to pay dividends unless certain financial covenants are satisfied. In addition, certain of SpectraSite’s subsidiaries are subject to restrictions on the amount of cash that they can distribute to us under the loan agreement related to our Securitization.

For more information about the restrictions under the loan agreement for the Revolving Credit Facility and Term Loan, our notes indentures and the loan agreement related to our Securitization, see Item 7 of this Annual Report under the caption “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources—Factors Affecting Sources of Liquidity” and note 6 to our consolidated financial statements included in this Annual Report.

Performance Graph

This performance graph is furnished and shall not be deemed “filed” with the SEC or subject to Section 18 of the Exchange Act, nor shall it be deemed incorporated by reference in any of our filings under the Securities Act of 1933, as amended.

The following graph compares the cumulative total stockholder return on our Common Stock with the cumulative total return of the S&P 500 Index and the Dow Jones USU.S. Telecommunications Equipment Index. The performance graph assumes that on December 31, 2004,2005, $100 was invested in each of our Common Stock, the S&P 500 Index and the Dow Jones USU.S. Telecommunications Equipment Index. The cumulative return shown in the graph assumes reinvestment of all dividends. The performance of our Common Stock reflected below is not necessarily indicative of future performance.

Recent Sales of Unregistered Securities

		Cumulative Total Returns
		12/05				12/06				12/07				12/08				12/09				12/10
American Tower Corporation		$	100.00			$	137.56			$	157.20			$	108.19			$	159.45			$	190.55
S&P 500 Index			100.00				115.80				122.16				76.96				97.33				111.99
Dow Jones U.S. Telecommunications Equipment Index			100.00				116.46				120.28				71.50				107.84				111.39

During the three months ended December 31, 2009, we issued an aggregate of 40,019 shares of our Common Stock upon the exercise of 5,675 warrants assumed in our merger with SpectraSite, Inc. In August 2005, in connection with the merger, we assumed approximately 1.0 million warrants to purchase shares of SpectraSite, Inc. common stock. Upon completion of the merger, each warrant to purchase shares of SpectraSite, Inc. common stock automatically converted into a warrant to purchase 7.15 shares of Common Stock at an exercise price of $32 per warrant. As some of these warrants were exercised pursuant to a cashless net exercise pursuant to the warrant agreement, net proceeds from these warrant exercises were $181,504. The shares were

issued in reliance on the exemption from registration set forth in Sections 3(a)(9) and 3(a)(10) of the Securities Act of 1933, as amended, and Section 1145 of the United States Code. No underwriters were engaged in connection with such issuances.

Issuer Purchases of Equity Securities

During the three months ended December 31, 2009,2010, we repurchased 661,6401,460,682 shares of our Common Stock for an aggregate of $27.6$74.6 million, including commissions and fees, pursuant to our publicly announced stock repurchase program, as follows:

Subsequent to December 31, 2009,2010, we repurchased 770,4511,122,481 shares of our Common Stock for an aggregate of $33.5$58.0 million, including commissions and fees, pursuant to the 2008 Buyback. As of February 12, 2010,11, 2011, we had repurchased a total of 21.330.9 million shares of our Common Stock for an aggregate of $781.6 million,$1.2 billion, including commissions and fees pursuant to the 2008 Buyback. We expect to continue to manage the pacing of the remaining $718.4$273.1 million under the 2008 Buyback in response to general market conditions and other relevant factors.

ITEM 6.

SELECTED FINANCIAL DATA

You should read the selected financial data in conjunction with our “Management’s Discussion and Analysis of Financial Condition and Results of Operations,” and our audited consolidated financial statements and the related notes to those consolidated financial statements included in this Annual Report.

Our continuing operations are reported in two segments: rental and management and network development services. In accordance with accounting principles generally accepted in the United States (“GAAP”), the consolidated statements of operations for all periods presented in this “Selected Financial Data” have been adjusted to reflect certain businesses as discontinued operations (see note 1 to our consolidated financial statements included in this Annual Report).

Year-over-year comparisons are significantly affected by our acquisitions, dispositions and, to a lesser extent, construction of towers. Our August 2005 merger with SpectraSite, Inc., as well as the change in the estimated useful lives of our tower assets in 2008, impacts the comparability of reported results between certain periods.

ITEM 7.

MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

The discussion and analysis of our financial condition and results of operations that followsfollow are based upon our consolidated financial statements, which have been prepared in accordance with GAAP. The preparation of our financial statements requires us to make estimates and judgments that affect the reported amounts of assets and liabilities, revenues and expenses, and the related disclosuresdisclosure in our financial statements. Actual results may differ significantly from these estimates under different assumptions or conditions. This discussion should be read in conjunction with our consolidated financial statements herein and the accompanying notes thereto, and the information set forth under the caption “Critical Accounting Policies and Estimates” beginning aton page 45.40.

Our continuing operations are reported in two segments, rental and management and network development services. Management focuses on segment gross margin and segment operating profit as a means to measure operating performance in theseour business segments. We define segment gross margin as segment revenue less segment operating expenses excludingexcluding: depreciation, amortization and accretion; selling, general, administrative and development expense; and other operating expense. We define segment operating profit as segment gross margin less selling, general, administrative and development expense attributable to the segment, excluding stock-based compensation expense and corporate expenses. Segment gross margin and segment operating profit for the rental and management segmentsegments also include interest income, TV Azteca, net (see note 18 to our consolidated financial statements included herein). These measures of segment gross margin and segment operating profit are also before interest income, interest expense, loss on retirement of long-term obligations, other income (expense), net income attributable to noncontrolling interest, in net earnings of subsidiaries, income (loss) on equity method investments, income taxes and discontinued operations.

Executive Overview

Our principal operating segmentprimary business is leasing antenna space on multi-tenant communications sites to wireless service providers and radio and television broadcast companies. We refer to this business as our rental and management segment,operations, which accounted for approximately 97%98% of our total revenues and approximately 99% of our segment operating profit for the yearsyear ended December 31, 20092010. Increased expansion activity in international markets and 2008.changes to our organizational structure have led us to separately disclose our rental and management operations in two reportable segments: domestic rental and management and international rental and management. Through our network development services segment, we also offer tower-related services domestically, including site acquisition, zoning and permitting services and structural analysis services, which primarily support our site leasing business and the addition of new tenants and equipment on our sites. Accordingly, our continuing operations are now reported in three segments, domestic rental and management, international rental and management and network development services.

The majority of our tenant leases with wireless carriers are typically for an initial non-cancellable term of five to ten years, with multiple five-year renewal terms thereafter. Accordingly, nearly all of the revenue generated by our rental and management operations as of the end of December 2010 is recurring revenue that we should continue to receive in future periods. As of December 31, 2010, we had approximately $13.5 billion of non-cancellable tenant lease revenue, absent the impact of straight-line lease accounting. In addition, most of our tenant leases have provisions that periodically increase the rent due under the lease. These contractual rent escalations are typically annual and based on a fixed percentage (generally three to five percent), inflation, or a fixed percentage plus inflation. Revenue generated by rent increases based on fixed escalation clauses is recognized on a straight-line basis over the non-cancellable term of the applicable agreement. We also routinely seek to extend our tenant leases with our tenants, which increases the non-cancellable term of the lease and creates incremental growth in our revenues.

The revenues generated by our rental and management operations may also be affected by cancellations of existing tenant leases. As discussed above, most of our tenant leases with wireless carriers and broadcasters are multi-year contracts, which typically may not be cancelled or, in some instances, may be cancelled only upon payment of a termination fee. Accordingly, revenue lost from either cancellations of leases at the end of their

terms or rent negotiations historically have not had a material adverse effect on the revenues generated by our rental and management operations. During the year ended December 31, 2010, loss of annual revenue from tenant lease cancellations or renegotiations represented less than 3% of our rental and management operations revenues.

Rental and Management Operations Revenue Growth. The primary factors affecting the consistent incremental growth in our revenues and cash flows for this segment are our recurringdomestic and international rental and management segments are:

We continue to believe that our site leasing revenue is likely to increase due to the growing use of wireless communications services and our ability to increasemeet that demand by adding new tenants and new equipment for existing tenants on our legacy sites, which increases the utilization and profitability of our existing site capacity.sites. In addition, we believe the majority of our site leasing activity will continue to come from customers providing wireless broadband services. Asservice providers. Our legacy site portfolio and our established tenant base provide us with new business opportunities, which have historically resulted in consistent and predictable organic revenue growth. In addition, we intend to continue to primarily focussupplement the organic growth on growing our rental and management business, we anticipate that our network development services revenue will continue to represent a small percentage of our total revenues.

The majority of our tenant leases with wireless carriers are typically for an initial non-cancelable term of five to ten years, with multiple five-year renewal terms thereafter. Accordingly, nearly all of the revenue generated by our rental and management segment as of the end of December 2009 is recurring revenue that we should continue to receive in future periods. In addition, most of our tenant leases have provisions that periodically increase the rent due under the lease. These contractual escalations are typically annual and are based on a fixed percentage (generally three to five percent), inflation, or a fixed percentage plus inflation. Revenue generated by rate increases based on fixed escalation clauses is recognized on a straight-line basis over the non-cancelable term of the applicable agreement. We also routinely seek to extend our tenant leases with our customers, which increases the non-cancelable term of the agreement and creates incremental growth in our revenues and cash flows.

The revenues generated by our rental and management segment may also be affected by cancellations of existing customer leases. As discussed above, most of our tenant leases with wireless carriers and broadcasters

are multi-year contracts, which typically may not be cancelled or, in some instances, may be cancelled only upon payment of a termination fee. Accordingly, lease cancellations historically have not had a material adverse effect on the revenues generated by our rental and management segment. During the year ended December 31, 2009, tenant leases representing approximately 2% of our rental and management revenues were cancelled.

During the year ended December 31, 2009, revenues generated by our rental and management segment increased $121.4 million from the year ended December 31, 2008. The increase was primarily attributable to incremental revenue generated by our legacy sites which resulted from leasing additional spaceby selectively developing or acquiring new sites in our existing and new markets where we can achieve our return on investment criteria.

Rental and Management Operations Organic Revenue Growth. Consistent with our strategy to increase the utilization and return on investment of our legacy sites, our objective is to add new tenants leasing additional spaceand new equipment for the equipment of our existing tenants as well as contractual tenant lease escalations. To a lesser extent, a portion ofon our revenue growth was attributable to the 4,511 new sites that we acquired or constructed since January 1, 2008. The increase in revenue was partially offset by tenant lease cancellations as well as the negative impact of foreign currency exchange rate fluctuations and a reduction in straight-line revenue recognition.

legacy sites. Our ability to lease additional space on our sites is a function of the rate at which wireless carriers deploy capital to improve and expand their wireless networks and, to a lesser extent, the location of and available capacity on our existing sites. This rate, in turn, is influenced by the growth of wireless communications services and related infrastructure needs, the financial performance of our customerstenants and their access to capital, and general economic conditions. Key trends within each market that we serve provide opportunities for organic revenue growth.

In addition, wireless service providers in the United States continue to pursue new avenues for growth, such as deploying 4G technology based wireless networks to provide higher speed data services and enable fixed broadband substitution. As wireless service providers begin to deploy 4G wireless networks, we expect them to overlay 4G equipment across their existing networks of communications sites, resulting in additional revenue. Subsequent to the initial deployment and based on actual subscriber demand, we expect providers to add additional equipment and new communications sites to improve the coverage and capacity of their 4G wireless networks as subscribers transition from 3G handsets. In connection with consistent levels of annual wireless carrier capital investment, this technology migration path has historically provided consistent demand for our communications sites as our tenants migrate their networks from one technology to the next to remain competitive.

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International. In general, our international markets are less advanced with respect to the current technologies deployed for wireless services. As a result, demand for our communications sites is driven by continued voice network investments, new market entrants and initial 3G data network deployments. For example, in India, nationwide voice networks continue to be deployed as wireless service providers are beginning their initial investments in 3G data networks, as a result of recent spectrum auctions. In Mexico and Brazil, where nationwide voice networks have been deployed, some incumbent wireless service providers continue to invest in their 3G data networks, and recent spectrum auctions have enabled other incumbent wireless service providers and new market entrants to begin their initial investments in 3G data networks. In markets such as Chile and Peru, recent spectrum auctions have attracted new market entrants, who are expected to begin their investment in deploying nationwide voice and 3G data networks. We believe demand for our tower sites will continue in our international markets as wireless service providers seek to remain competitive by increasing the coverage of their networks while also investing in next generation data networks.

Rental and Management Operations New Site Revenue Growth. During the year ended December 31, 2010, we grew our portfolio of communications sites through acquisitions and construction activities, including the acquisition and construction of approximately 7,800 sites. We continue to evaluate opportunities to acquire larger communications site portfolios, both domestically and internationally, that we believe we can effectively integrate into our existing portfolio.

Network Development Services Segment Revenue Growth. As we continue to focus on growing our rental and management operations, we anticipate that our network development services revenue will continue to represent a small percentage of our total revenues. Through our network development services segment, we offer tower-related services, including site acquisition, zoning and permitting services and structural analysis services, which primarily support our site leasing additional spacebusiness and the addition of new tenants and equipment on our existing sitessites.

Rental and expanding our site portfolio will contribute to the majority of our year-over-year revenue growth in 2010.

Management Operations Expenses.Our rental and management segment operatingoperations expenses include our direct site level expenses and consist primarily of ground rent, property taxes, repairs and maintenance and utilities. These segment level expenses exclude all segment and corporate level selling, general, administrative and development expenses, which are aggregated into one line item entitled selling, general, administrative and development expense. Our segment level selling,In general, administrative and development expenses consist of expenses to support our rental and management and network development services segments, such as sales and property management functions. In general, our segment level selling, general and administrative expenses do not significantly increase as a result of adding incremental customerstenants to our legacy sites and typically increase only modestly year-over-year. As a result, leasing additional space to new customerstenants on our legacy sites provides significant incremental cash flow. In geographic areas where we have recently launched operations or are focused on materially expanding our site footprint, we may incur additional segment level selling, general and administrative expenses as we increase our presence in these areas. Our profit margin growth is therefore positively impacted by the addition of new tenants to our legacy sites and can be temporarily diluted by our development activities.

REIT Election. As we review our tax strategy and assess the utilization of our federal and state NOLs, we are actively considering an election to a REIT for U.S. federal and, where applicable, state income tax purposes. We may make the determination to elect REIT status for the taxable year beginning January 1, 2012, as early as the second half of 2011, subject to the approval of our board of directors, although there is no certainty as to the timing of a REIT election or whether we will make a REIT election at all.

Non-GAAP Financial Measures

Included in our analysis of our results of operations are discussions regarding earnings before interest, taxes, depreciation, amortization and accretion, as adjusted (“Adjusted EBITDA”). We define Adjusted EBITDA as net income before: income (loss) from discontinued operations, net; income from equity method investments; income tax provision (benefit); other income (expense); loss on retirement of long-term obligations; interest expense; interest income; other operating expenses; depreciation, amortization and accretion; and stock-based compensation expense.

Adjusted EBITDA is not intended to replace net income or any other performance measures determined in accordance with GAAP. Rather, Adjusted EBITDA is presented as we believe it is a useful indicator of our current operating performance. We believe that Adjusted EBITDA is useful to an investor in evaluating our operating performance because it is the primary measure used by our management team when evaluating the performance of our operating segments, it is a component of the calculation used by our lenders to determine compliance with certain debt covenants and it is widely used in the tower industry to measure operating performance as depreciation, amortization and accretion may vary significantly among companies depending upon accounting methods and useful lives, particularly where acquisitions and non-operating factors are involved.

Our measurement of Adjusted EBITDA may not be comparable to similarly titled measures used by other companies. A reconciliation of Adjusted EBITDA to net income, the most directly comparable GAAP measure, has been included below.

Results of Operations

Years Ended December 31, 2010 and 2009

(In thousands)

Revenue

Total revenues for the year ended December 31, 2010 increased 15% to $1,985.3 million. The increase was primarily attributable to an increase in both of our rental and management segments, including organic revenue growth attributable to our legacy sites and revenue growth attributable to the approximately 11,400 new sites that we have constructed or acquired since January 1, 2009. This growth was partially offset by a decrease in network development services segment revenue.

Domestic rental and management segment revenue for the year ended December 31, 2010 increased 11% to $1,565.5 million. This growth was comprised of:

International rental and management segment revenue for the year ended December 31, 2010 increased 43% to $370.9 million. This growth was comprised of:

Network development services segment revenue for the year ended December 31, 2010 decreased 12% to $49.0 million. The decrease was primarily attributable to revenues generated during the year ended December 31, 2009 for a material acquisition, zoning and permitting project with a major tenant, which did not recur in 2010.

Gross Margin

Total gross margin for the year ended December 31, 2010 increased 15% to $1,525.0 million. The increase was primarily attributable to an increase in both of our rental and management segments and was partially offset by a decrease in gross margin attributable to our network development services segment.

Domestic rental and management segment gross margin for the year ended December 31, 2010 increased 13% to $1,240.1 million. The growth was primarily attributable to the increase in revenue as described above, and was partially offset by a 4% increase in direct operating costs, of which 1% was attributable to expense increases on our legacy domestic sites and 3% was attributable to the incremental direct operating costs associated with the addition of approximately 1,500 new domestic sites since January 1, 2009.

International rental and management segment gross margin for the year ended December 31, 2010 increased 30% to $262.8 million. The growth was primarily attributable to the increase in revenue as described above, and was partially offset by a 70% increase in direct operating costs, including pass-through expenses, of which 10% was attributable to expense increases on our legacy international sites and 60% was attributable to the incremental costs associated with the addition of approximately 9,900 new international sites since January 1, 2009.

Network development services segment gross margin for the year ended December 31, 2010 decreased 6% to $22.0 million. The decrease was primarily attributable to the reduction in revenue attributable to our site acquisition, zoning and permitting services.

Selling, General, Administrative and Development Expense

Total selling, general, administrative and development expense for the year ended December 31, 2010, increased 14% to $229.8 million. The increase was primarily attributable to an increase in both of our rental and management segments and corporate overhead to support the continued growth of our operations. These increases were partially offset by lower stock-based compensation expense.

Domestic rental and management segment selling, general, administrative and development expense for the year ended December 31, 2010 increased 12% to $62.3 million. The increase was primarily attributable to initiatives designed to drive growth and to support a growing portfolio, including increased staffing in field operations, sales and finance, as well as costs associated with establishing a dedicated team to more actively pursue new product lines, such as shared generators and outdoor DAS networks.

International rental and management segment selling, general, administrative and development expense for the year ended December 31, 2010, increased 50% to $45.9 million. The increase was primarily attributable to our increased international expansion, including acquisitions of several tower businesses in India, as well as costs associated with our recent expansion initiatives in Chile, Colombia and Peru.

Network development services segment selling, general, administrative and development expense for the year ended December 31, 2010 increased 9% to $6.3 million. The increase was primarily attributable to costs incurred to support our new tower development and our site acquisition, zoning and permitting services.

Other selling, general administrative and development expense for the year ended December 31, 2010, increased 5% to $115.3 million. The increase was primarily due to a $13.7 million increase in corporate expenses, which were partially offset by a $8.1 million decrease in stock-based compensation expense. The increase in corporate expenses was primarily attributable to incremental employee and increased information technology costs associated with supporting a growing global organization. The decrease in stock-based compensation expense was primarily attributable to the one-time expense recognized upon the modification of certain equity awards in 2009, which did not recur in 2010.

Operating Profit

Total operating profit for the year ended December 31, 2010 increased 15% to $1,410.5 million. The increase was primarily attributable to the increase in both our rental and management segments gross margin, and was partially offset by increases in overhead costs attributable to both of our rental and management segments.

Domestic rental and management segment operating profit for the year ended December 31, 2010 increased 13% to $1,177.8 million. The growth was primarily attributable to the increase in our domestic rental and management segment gross margin (13%) as described above, and was partially offset by increases in our domestic rental and management segment overhead costs (12%), as described above.

International rental and management segment operating profit for the year ended December 31, 2010 increased 26% to $217.0 million. The growth was primarily attributable to the increase in our international rental and management segment gross margin (30%) as described above, and was partially offset by increases in our international rental and management segment overhead costs (50%), as described above.

Network development services segment operating profit for the year ended December 31, 2010 decreased 10% to $15.7 million. The decrease was primarily attributable to the decrease in revenue and an increase in segment overhead costs, as described above.

Depreciation, Amortization and Accretion

Depreciation, amortization and accretion for the year ended December 31, 2010 increased 11% to $460.7 million. The increase was primarily attributable to the depreciation, amortization and accretion associated with the acquisition or construction of approximately 7,800 sites since January 1, 2010, which resulted in an increase in property and equipment.

Other Operating Expenses

Other operating expenses for the year ended December 31, 2010 increased 87% to $35.9 million. The increase was primarily attributable to an increase of approximately $10.7 million in acquisition related costs, an increase of approximately $4.1 million in impairments and losses on the sale of assets, and an increase of $1.7 million of consulting and legal costs associated with our evaluation of a potential election to a REIT.

Interest Expense

Interest expense for the year ended December 31, 2010 decreased 2% to $246.0 million. The decrease was primarily attributable to a reduction in our weighted average cost of borrowing from 5.82% to 5.52%, partially offset by an increase in average debt outstanding.

Income Tax Provision

The income tax provision for the year ended December 31, 2010 remained relatively flat at $182.5 million. The effective tax rate for the year ended December 31, 2010 decreased to 32.8% from 43.3%. The decrease in the effective tax rate was primarily due to reduced foreign withholding taxes, the recognition of previously reserved NOLs and a reduction in the foreign currency impact on certain tax items.

The effective tax rates on income from continuing operations for the years ended December 31, 2010 and 2009 differ from the federal statutory rate due primarily to adjustments for foreign items, non-deductible stock-based compensation expense, tax reserves and state taxes.

Net Income/Adjusted EBITDA