AMERICAN TOWER CORP /MA/
10-K, 1999-03-19
COMMUNICATIONS SERVICES, NEC
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                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
 
                               ----------------
 
                                   FORM 10-K
 
                       FOR ANNUAL AND TRANSITION REPORTS
                    PURSUANT TO SECTIONS 13 OR 15(d) OF THE
                        SECURITIES EXCHANGE ACT OF 1934
 
(Mark One)
[X]ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT
   OF 1934
 
                  For the fiscal year ended December 31, 1998
 
                                       OR
 
[_]TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES ACT OF
   1934
 
                For the transition period from        to       .
 
                        Commission file number 333-46025
 
                           AMERICAN TOWER CORPORATION
             (Exact name of registrant as specified in its charter)
 
                Delaware                               65-0723837
    (State or other jurisdiction of                 (I.R.S. Employer
     incorporation or organization)               Identification No.)
 
                             116 Huntington Avenue
                          Boston, Massachusetts 02116
             (Address of principal executive offices and Zip Code)
 
                                 (617) 375-7500
              (Registrant's telephone number, including area code)
 
          Securities registered pursuant to Section 12 (b) of the Act:
 
<TABLE>
<CAPTION>
                                                  Name of exchange on
                (Title of Class)                    Which Registered
                ----------------                  -------------------
 <C>                                            <S>
     Class A Common Stock, $0.01 par value      New York Stock Exchange
</TABLE>
 
          Securities registered pursuant to Section 12 (g) of the Act:
                                (Title of Class)
 
                                      None
 
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 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 this Form 10-K or any amendment to
this form 10-K. [_]
 
The aggregate market value of the voting and non-voting common equity held by
non-affiliates of the registrant as of March 15, 1999 was approximately
$3,031,352,000. As of March 15, 1999, 145,826,760 shares of Class A Common
Stock, 8,943,773 shares of Class B Common Stock and 2,422,804 shares of the
Class C Common Stock were issued and outstanding.
 
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                           AMERICAN TOWER CORPORATION
 
                               TABLE OF CONTENTS
 
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                                                                           Page
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 <C>       <S>                                                             <C>
 PART I.
 ITEM 1.   Business.....................................................     1
 ITEM 2.   Properties...................................................    14
 ITEM 3.   Legal Proceedings............................................    14
 ITEM 4.   Submission of Matters to a Vote of Security Holders..........    14
 PART II.
           Market for the Registrant's Common Equity and Related
 ITEM 5.   Stockholder Matters..........................................    14
 ITEM 6.   Selected Financial Data......................................    16
 ITEM 7.   Management's Discussion and Analysis of Financial Condition
            and Results of Operations...................................    18
 ITEM 7A.  Quantitative and Qualitative Disclosures About Market Risk...    26
 ITEM 8.   Financial Statements and Supplementary Data..................    27
 ITEM 9.   Changes In and Disagreements With Accountants On Accounting
            and Financial Disclosure....................................    27
 PART III.
 ITEM 10.  Directors and Executive Officers of the Registrant...........    27
 ITEM 11.  Executive Compensation.......................................    30
           Security Ownership of Certain Beneficial Owners and
 ITEM 12.  Management...................................................    34
 ITEM 13.  Certain Relationships and Related Transactions...............    37
 PART IV.
           Exhibits, Financial Statement Schedules, and Reports on Form
 ITEM 14.  8-K..........................................................    39
           Signatures...................................................    40
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             CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS
 
  We have made and incorporated by reference forward-looking statements in
this document. Forward-looking statements include those regarding our goals,
beliefs, plans or current expectations and other statements contained
regarding matters that are not historical facts. For example, when we use the
words "believe", "expect", "anticipate", or similar expressions, we are making
forward-looking statements. Forward-looking statements include statements
concerning;
 
  .  the outcome of our growth strategy,
 
  .  future results of operations,
 
  .  liquidity and capital expenditures,
 
  .  construction and acquisition activities,
 
  .  debt levels and the ability to obtain financing and service debt,
 
  .  competitive conditions in the communications site and wireless carrier
     industries,
 
  .  regulatory developments in the communications site and wireless carrier
     industries,
 
  .  projected growth of the wireless communications and wireless carrier
     industries, and
 
  .  general economic conditions.
 
  Our forward-looking statements are subject to risks and uncertainties. You
should note that many factors, some of which are discussed elsewhere in this
document, could affect our company in the future and could cause our results
to differ materially form those expressed in our forward-looking statements.
We do not undertake to release publicly the results of any revisions to these
forward-looking statements that may be made to reflect future events or
circumstances.
 
                                NOTE TO READER
 
  The Way We Describe Ourselves in this Document
 
  American Tower Corporation ("the Company", "ATC" or "American Tower") has
been actively buying and merging with other companies and raising capital for
its business. We believe you will have a better understanding of us if we show
how we look with all those transactions included. Therefore, we present some
of the information in this document on a "what if" basis to show how we would
look if we had owned these companies for all of the various periods or now.
This information includes only the major acquisitions and mergers and other
transactions and assumes that they had occurred as of January 1, 1998.
Management expects that acquisitions consummated and construction completed to
date will have a material impact on future revenues, expenses, income from
continuing operations and capital expenditures. The historical 1998 financial
information does not reflect the impact of these items and should be read in
that context.
 
ITEM 1. BUSINESS.
 
General
 
  American Tower is a leading independent owner, operator and developer of
wireless communications and broadcast towers in the United States. ATC's
strategy is to use its leading position to take advantage of the growth
opportunities inherent in the rapidly expanding and highly fragmented
communications site industry. ATC has grown in less than four years to a
company that operates more than 3,200 towers in 44 states and the District of
Columbia, giving effect to pending transactions.
 
  ATC's primary business is the leasing of antennae sites on multi-tenant
towers to a diverse range of wireless communications industries, including
personal communications services ("PCS"), paging, cellular, enhanced
specialized mobile radio ("ESMR"), specialized mobile radio ("SMR"), and fixed
microwave, as well as radio
 
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and television broadcasters. ATC also offers its customers a broad range of
network development services, including network design, site acquisition,
zoning and other regulatory approvals, tower construction and antennae
installation. ATC is also engaged in the video, voice, data and Internet
transmission business, which it currently conducts in the New York City to
Washington, D.C. corridor and Texas. ATC operates or is constructing towers in
major cities throughout the United States and has its largest tower clusters
in California, Florida and Texas.
 
  American Tower achieved its growth predominantly through acquisitions. ATC
intends to continue to pursue strategic acquisitions, including possible
transactions with large wireless service providers seeking to divest their
ownership of towers. More recently, however, ATC has been engaged in a major
construction program. In 1998, American Tower (exclusive of construction
activities of acquired or to be acquired companies prior to acquisition)
constructed or had under construction at year-end more than 500 towers at an
aggregate cost of approximately $116.8 million. ATC also built an additional
300 towers for third parties. The 1999 business plan of ATC calls for
construction of between 1,200 and 1,600 towers at a cost of between $216.0
million and $304.0 million (exclusive of broadcast towers). The actual number
of towers built may be outside of that range because of more attractive
investment opportunities from acquisitions (in which case it could be less) or
significant new build to suit projects with wireless service providers (in
which case it could be more).
 
  ATC has a diversified base of approximately 3,900 customers. No customer
accounted for more than 10% of its operating revenues for the year ended
December 31, 1998. The five largest customers accounted for less than 30% of
1998 revenues. ATC's wide range of customers include most of the major
wireless service providers, including Airtouch, Alltell, AT&T Wireless, Bell
Atlantic Mobile, BellSouth, GTE Mobilnet, Houston Cellular, Metrocall, Mobile
Comm, Nextel, Omnipoint, PacBell, PageNet, PowerTel, PrimeCo PCS, SkyTel,
Southwestern Bell, Sprint PCS and Western Wireless. In addition, most of the
major radio and television broadcasters are ATC's customers, including ABC,
CBS, Chancellor Media, Clear Channel, CNN, Fox and NBC. ATC provides site
acquisition services to most of the major wireless service providers. It has
constructed or is constructing towers on a build to suit basis for several of
those carriers. The principal users of ATC's video, voice, data and Internet
transmission services are television broadcasters and other video suppliers,
such as CBS, CNN, Fox and TCI.
 
  Management estimates that ATC's site leasing activities, which generates the
highest profit margin of its businesses, accounted for 58.4% of its operating
revenues for the year ended December 31, 1998; services (primarily site
acquisition activities) accounted for 22.5% of such revenues; and the video,
voice, data and Internet transmission business accounted for 19.1% of such
revenues. ATC believes that leasing activities are likely to grow at a more
rapid rate than other aspects of its business because of its intention to
focus on build to suit and other construction activities.
 
  ATC derives its revenue from various industry sectors. The percentage of
ATC's annual run-rate revenues (based on December 1998) derived from the
various industry sectors is estimated to be as follows: PCS 24%; paging 20%;
major television networks (teleports) 14%; cellular 7%; fixed microwave 2%;
radio and television broadcasting 6%; ESMR 6%; two-way radio 6%; SMR 4% and
governmental agencies and others 11%. Management believes that the foregoing
percentages are probably not indicative of future contributions to be made by
the various industry sectors. Future contributions will probably change
because of the anticipated growth of PCS, cellular and ESMR compared to other
wireless providers. Management's intended operational strategy will also
impact relative contributions. Moreover, PCS's ongoing percentage of operating
revenues may decline over time because its anticipated growth in lease
revenues will be more than offset by the decline in ATC's site acquisition and
construction activities for that sector.
 
  ATC designed its growth strategy to enhance its position as a leading U.S.
provider of communications sites and network development services to the
wireless communications and broadcasting industries. The principal elements of
this strategy are to:
 
  .  maximize utilization of antennae sites through targeted sales and
     marketing techniques;
 
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  .  expand its tower construction activities, principally through build to
     suit projects;
 
  .  pursue strategic acquisitions, designed principally (i) to take
     advantage of divestiture opportunities presented by wireless service
     providers, (ii) to facilitate entry into new geographic markets and
     (iii) to complement the construction program.
 
Industry Overview
 
  ATC's growth strategy seeks to capitalize on the rapid expansion taking
place in the wireless communications industry. ATC believes the increase in
demand for wireless communications is attributable to a number of factors.
These include:
 
  .  decreasing costs of wireless services;
 
  .  increasing mobility of the U.S. population;
 
  .  the growing awareness of the benefits of mobile communications;
 
  .  technological advances in communications equipment;
 
  .  favorable changes in telecommunications regulations; and
 
  .  business and consumer preferences for higher quality voice and data
     transmission.
 
  The Cellular Telecommunications Industry Association estimates that the
number of subscribers to wireless telephone services was approximately five
million in 1990. According to The Yankee Group, a telecommunications marketing
research firm, the number of subscribers to cellular and PCS was over 60
million in 1998 and is projected to increase to over 122 million by the year
2003. Contributing significantly to the anticipated requirements is the nature
of PCS and ESMR. These higher frequency technologies have a reduced cell range
and thus require a higher density of towers in the network. Consequently, the
anticipated increase in the demand for these technologies will require more
towers to be built. The Personal Communications Industry Association (of which
James S. Eisenstein, an executive officer of ATC, is a director) estimates
that cellular and PCS needs will require the construction of over 100,000
additional antennae sites over the next ten years.
 
  ATC believes that as the wireless communications industry has grown, the
industry has become more competitive. As a consequence, many carriers may seek
to preserve capital and speed access to their markets by (i) focusing on
activities that contribute directly to subscriber growth, (ii) outsourcing
infrastructure requirements such as owning, constructing and maintaining
towers and/or (iii) by co-locating transmission facilities. ATC also believes
that the co-location trend is likely to be accelerated because of regulatory
restrictions and the growing tendency of local municipalities seeking to slow
the proliferation of towers in their communities by requiring that towers
accommodate multiple tenants. Management believes that national and other
large wireless service providers will prefer to deal with a company, such as
ATC, that can meet the majority of such providers' needs within a particular
market or region, rather than, as in the past, when carriers typically sourced
many of such services in-house, while local non-integrated service contractors
focused on specific segments such as radio frequency engineering, site
acquisition and tower construction.
 
  Management believes that, in addition to such favorable growth and
outsourcing trends, the communications site industry and ATC will benefit from
several favorable industry characteristics, including the following:
 
  .  a recurring and growing revenue stream due in part to long-term leases;
 
  .  low tenant "churn" due to the costs and disruption associated with
     reconfiguring a wireless network or broadcasting location;
 
  .  a customer base which is diversified by industry which consists
     principally of large, financially responsible national companies;
 
  .  favorable absolute and incremental tower cash flow margins due to low
     variable operating costs;
 
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  .  low on-going maintenance capital requirements;
 
  .  local government and environmental initiatives to reduce the number of
     towers thereby requiring carriers to co-locate antennae; and
 
  .  the opportunity to consolidate in a highly fragmented industry, thereby
     creating the potential for enhanced levels of customer service and
     operating efficiency.
 
  While the wireless communications industry is experiencing rapid growth, the
television broadcasting industry, with strong encouragement from both Congress
and the FCC, is actively planning its strategy for the transition from analog
to digital technology. ATC believes that this transition will require a
substantial investment in enhanced broadcast infrastructure, including the
construction or reengineering of broadcast towers. ATC expects much of the
associated capital requirements will be borne by the broadcasters. However,
management believes that, as with the deployment of towers for the wireless
carriers, speed to market and limited capital resources will cause certain
broadcasters to outsource the construction or reengineering of their towers in
order to accommodate digital technology.
 
Growth Strategy
 
  ATC's objective is to enhance its position as a leading U.S. provider of
communications sites and network development services to the wireless
communications and broadcasting industries. ATC's growth strategy consists of
the following principal elements:
 
  Internal Growth through Sales, Service and Capacity Utilization. Management
believes that a substantial opportunity for profitable growth exists by
maximizing the utilization of existing and future towers. Because the costs of
operating a site are largely fixed, increasing tower utilization significantly
improves site operating margins. Moreover, when a specific tower reaches full
antennae attachment capacity, ATC is often able to construct an additional
tower at the same location, thereby further leveraging its investment in land,
related equipment and certain operating costs, such as taxes, utilities and
telephone service.
 
  ATC intends to use targeted sales and marketing techniques to increase
utilization of both existing and newly constructed towers and to maximize
investment returns on acquired towers with underutilized capacity. Management
believes that the key to the success of this strategy lies in its ability to
develop and consistently deliver a high level of customer service, and to be
widely recognized as a company that makes realistic commitments and then
delivers on them. Since speed to market and reliable network performance are
critical components to the success of wireless service providers, ATC's
ability to assist its customers in meeting these goals will ultimately define
its marketing success and capacity utilization. ATC targets wireless service
providers that are expanding or improving their existing network
infrastructure as well as those deploying new technologies.
 
  Growth by Construction. ATC believes it can achieve attractive investment
returns by constructing new tower clusters in and around markets in which it
already has a presence, along major highways and in targeted new markets,
particularly markets that have not been significantly built out by carriers or
other communications site companies. By working with one or more "anchor"
tenants, ATC will seek to develop an overall master plan for a particular
network by locating new sites in areas identified by its customers as optimal
for their network expansion requirements. ATC generally secures commitments
for leasing prior to commencing construction, thereby minimizing, to some
extent, the risks associated with the investment. In some cases, ATC may
invest in the zoning and permitting of sites (and even the construction of
towers) when it has no anchor tenant, but believes that demand will exist in
the near term. ATC will also pursue strategic acquisitions as a means of
filling out or, in certain cases, initiating a tower cluster.
 
  Management intends to place a strong emphasis on new tower development for
the foreseeable future because it believes that new tower construction can
produce relatively attractive initial returns. In addition, ATC can design and
build towers to specifications that assure ample future capacity and minimize
the need for future
 
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capital expenditures. Management also intends to pursue new tower construction
to service the demand for digital television and for tower space for radio
antennae displaced by digital television requirements. Over time, management
believes that as many as half of its towers will result from construction,
with the vast majority of these designed to serve the wireless communications
industry.
 
  The 1999 business plan of ATC calls for construction of between 1,200 and
1,600 towers at a cost of between $216.0 million and $304.0 million (exclusive
of broadcast towers). The actual number of towers built may be outside of that
range because of more attractive investment opportunities from acquisitions
(in which case it could be less) or significant new build to suit projects
with wireless service providers (in which case it could be more). The scope of
ATC's forecasted construction program is substantially greater than the
combined past construction programs of ATC and the various companies it has
acquired. As a consequence, ATC may not have enough experienced and qualified
personnel to complete its construction program on time and within budget.
Personnel shortages may also affect ATC's ability to manage effectively the
substantially increased number of towers it is constructing and acquiring.
 
  American Tower, and others in the industry, are increasingly devoting their
construction activities to build to suit projects. Under these arrangements,
ATC, and others, agree with a major wireless service provider to build a
network of a significant number of towers to the provider's specification.
Build to suit activities involve certain additional risks. Although such
projects involve an "anchor" tenant, ATC may not be able to secure a
sufficient number of additional tenants to ensure adequate investment returns.
This may be particularly true for the larger build to suit projects that ATC
is seeking. In fact, one of the reasons providers may be entering into build
to suit arrangements (rather than, as in the past, undertaking their own
construction) is that many of the proposed sites may be expensive or difficult
to build on or in undesirable locations for many other wireless service
providers. Such projects also entail the additional risk of a greater
dependence on a single customer with, in many instances, more favorable lease
and control provisions than those made available generally by ATC to its
tenants.
 
  The ability to obtain, and commit to, large new construction projects will
require significant financial resources. Management believes that its cost of
capital, relative to the cost of capital of its competitors, will be an
important factor in determining the success of its growth by construction
strategy. Based on its previous capital market transactions, management
believes that it has a good reputation in the financial community, including
among banks, investment banking firms, institutional investors and public
investors, and that such reputation will help it attract capital on the
favorable terms necessary to finance its growth. However, funds may not be
available to ATC on such terms.
 
  ATC's construction growth strategy is highly dependent on its ability to
complete tower construction in a timely and cost effective manner. ATC cannot
control the principal factors that can prevent, delay or increase the cost of
construction. Such factors include zoning and local permitting requirements,
environmental group opposition, availability of skilled construction personnel
and construction equipment, adverse weather conditions and federal
regulations. As the pace of tower construction has increased in recent years,
the required manpower and equipment have been in increasing demand. The
anticipated increase in construction activity, for both ATC and the industry,
could significantly increase costs and delay time schedules associated with
tower construction, either of which could have a material adverse effect on
ATC. The construction of towers to accommodate the introduction of digital
television service could be particularly affected by a potential shortage of
construction capability.
 
  Growth by Acquisition. ATC has achieved a leading industry position
primarily through acquisitions. ATC intends to continue to target strategic
acquisitions in markets or regions where it already owns towers as well as new
markets, possibly including non-U.S. markets.
 
  Among the potential acquisitions are tower networks owned by major wireless
service providers. These providers may seek to divest their ownership of such
networks for reasons similar to those motivating them to outsource their new
construction requirements. These transactions often involve ATC obtaining
future
 
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construction commitments for the seller's tower needs. The transactions may be
substantial, involving several thousand towers and purchase prices in the
hundreds of millions of dollars. Construction commitments which may attend
such acquisitions may also entail hundreds of millions of dollars of capital
expenditures. ATC has submitted proposals to several wireless service
providers in the past (none of which have resulted in definitive agreements to
date) and intends to continue to pursue such opportunities actively. ATC may
not necessarily enter into any such major transaction. ATC has experienced
increased competition for towers being divested by wireless service providers,
and believes such competition may intensify, resulting in substantially higher
prices to complete such transactions. Transactions with wireless service
providers entail the risk of dependence on a single customer with, in many
instances, more favorable lease and control provisions than those made
available generally by ATC to its tenants.
 
  ATC's current activities with respect to possible significant acquisitions
range from the evaluation of properties, to submissions of indications of
interests and first-round bids. These opportunities range in size from several
hundred towers to several thousand towers and from purchase prices of tens of
millions of dollars to several hundreds of millions of dollars. Such purchase
prices could take the form of cash, common stock or other securities, or a
combination thereof. No material acquisition has reached the legally binding
agreement stage other than those described in this document. See "--Recent
Transactions" below. ATC cannot predict whether it will enter into any binding
agreements with respect to major acquisitions or, if it does, their terms or
the timing of them. ATC would probably not require additional equity capital
to finance a limited number of such transactions with wireless service
providers seeking to divest ownership of their towers. However, more than a
limited number of such acquisitions, which is unlikely, could require an
equity financing, particularly since they would likely include major build to
suit construction commitments. See "--Competition" below.
 
  ATC will attempt to increase revenues and operating margins at acquired
communications sites through expanded sales and marketing efforts, improved
customer service, cost reductions and, in certain instances, increased tower
capacity. Acquisitions of communications towers and sites are evaluated using
numerous criteria, including potential demand, tower location, tower height,
existing capacity utilization, local competition and local government
restrictions on new tower development.
 
  ATC also intends to pursue, on a selective basis, the acquisition of site
acquisition companies and providers of video, voice, data and Internet
transmission services, and may pursue acquisitions related to the
communications site industry, including companies engaged in the tower
fabrication business.
 
Products and Services
 
  The Company operates in three business segments: tower rental and management
("TRM"), Services, and video, voice, data and Internet transmission services
("VVDI"). The TRM segment provides for the leasing and subleasing of antennae
sites on multi-tenant towers for a diverse range of wireless communication
industries, including PCS, paging, cellular, ESMR, SMR and fixed microwave, as
well as radio and television broadcasters. The Services segment offers a broad
range of network development services, including network design, site
acquisition and construction, zoning and other regulatory approvals, tower
construction and antennae installation. The VVDI segment offers transmission
services in the New York City to Washington, D.C. corridor and in Texas. See
the Consolidated Financial Statements and notes thereto, for information with
respect to the financial data by segment.
 
Tower Rental and Management Segment
 
  Leasing of Antennae Sites. ATC's primary business is the leasing of antennae
sites on multi-tenanted communications towers to companies in all segments of
the wireless communications and broadcasting industries. Giving effect to
pending transactions, ATC has more than 3,200 towers in 44 states and the
District of Columbia, approximately 600 of which are managed for others,
including approximately 400 rooftop antennae.
 
  ATC rents tower space and provides related services to a diverse range of
wireless communications industries, including PCS, paging, cellular, ESMR,
SMR, and fixed microwave, as well as radio and television
 
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broadcasters. ATC is geographically diversified with a significant number of
towers throughout the United States. Its largest tower clusters are in
California, Florida and Texas. ATC also owns and operates communications sites
or is constructing communications sites in cities such as Albuquerque,
Atlanta, Austin, Baltimore, Boston, Charlotte, Dallas, Houston, Jacksonville,
Kansas City, Los Angeles, Miami-Ft. Lauderdale, Minneapolis, Philadelphia,
Raleigh, San Antonio, San Diego, San Francisco, Tucson, Washington, D.C. and
West Palm Beach.
 
  ATC's leases, like most of those in the industry, generally vary depending
upon the industry user. Television and radio broadcasters prefer long-term
leases (generally from 15 to 20 years), and wireless communications providers
favor somewhat shorter lease terms (generally from five to ten years), with
multiple renewals at the option of the tenant. However, the leases acquired in
the merger with the old American Tower Corporation tend to be of shorter
duration, generally two years, and permit earlier termination if ATC were to
attempt to impose price increases relating to escalator provisions.
Governmental agencies, because of budgetary restrictions, generally have one-
year leases that tend to renew automatically. Tenants tend to renew their
leases because of the complications associated with moving antennae. For
example, a move by a television or radio broadcaster would necessitate Federal
Communications Commission ("FCC") approval and could entail major dislocations
and the uncertainty associated with building antennae in new coverage areas.
In the case of cellular, PCS and other wireless users, moving one antenna
might necessitate moving several others because of the interlocking grid-like
nature of their wireless systems. In addition, the increasing difficulty of
obtaining local zoning approvals, the increasing environmental concerns of
communities and the restrictions imposed upon owners and operators by the
Federal Aviation Administration ("FAA") and upon tenants by the FCC tend to
reduce the number of alternatives available to a tower user.
 
  Most of ATC's leases have escalator provisions (annual automatic increases
based on specified estimated cost measures or on increases in the consumer
price index). While these provisions are not by themselves intended to be a
primary source of growth, they provide a stable and predictable growth
component that is enhanced by increased tower utilization. ATC may also
receive fees if it is retained to install the customers' equipment and
antennae on the communications site.
 
  The number of antennae that ATC's towers can accommodate varies depending on
the type of tower (broadcast or non-broadcast), the height of the tower and
the nature of the services provided by such antennae. Non-broadcast towers of
200-300 feet that are designed to maximize capacity generally are capable of
housing between five and ten tenants using an aggregate of between 25 and 50
antennae. Broadcasting towers generally are capable of housing between ten and
forty tenants using an aggregate of between 50 and 100 antennae.
 
  Annual rental payments vary considerably depending upon (i) the type of
service being provided; (ii) the size of the transmission line and the number
and weight of the antennae on the tower; (iii) the existing capacity of the
tower; (iv) the antenna's placement on, and the location and height of, the
tower; and (v) the competitive environment. Management believes that it is not
possible to state with any degree of precision the vacancy or unused capacity
of a "typical" tower, group of related towers or all of its towers for a
variety of reasons, including, among others, the variations that occur
depending on the types of antennae placed on the tower, the types of service
being provided by the tower users, the type and location of the tower or
towers, the ability to build other towers so as to configure a network of
related towers, whether any of the users have imposed restrictions on
competitive users, and whether there are any environmental, zoning or other
restrictions on the number or type of users.
 
  ATC's antennae site leasing business is dependent on many factors that are
beyond its control, including, among other things (i) consumer demand for
wireless services; (ii) the financial condition of wireless service providers
and their preference for owning or leasing antennae sites; (iii) governmental
licensing of broadcast rights, zoning, environmental and other governmental
regulations; (iv) national and regional economic conditions, including a
slowdown in the growth of wireless communications, a downturn in a particular
wireless segment or a decrease in the number of carriers, nationally or
locally, in a particular segment; and (v) technological changes. Demand could
also be adversely affected by "roaming" and "resale" arrangements. These
arrangements enable a provider to serve customers outside its license area, to
give licensed providers the right to enter into arrangements to serve
overlapping license areas and to permit nonlicensed providers to enter
 
                                       7
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the wireless marketplace. Wireless providers might consider such roaming and
resale arrangements as superior to constructing their own facilities or
leasing antennae space from ATC. Any material decrease in demand or
proliferation of "roaming" and "resale" arrangements could have a material
adverse effect on ATC.
 
  The demand for antenna space is dependent, to a significantly lesser extent,
on the needs of television and radio broadcasters. Among other things, certain
technological advances, including the development of satellite-delivered
radio, may reduce the need for tower-based broadcast transmission. ATC could
also be affected adversely should the development of digital television be
delayed or impaired, or if demand for it were to be less than anticipated
because of delays, disappointing technical performance or cost to the
consumer.
 
  Communications Site Management Business. ATC is a leading manager of
communications sites. These are principally rooftop sites, but also ground
towers, for other owners. A principal aspect of this business is the
development of new sources of revenue for building owners by effectively
managing all aspects of rooftop telecommunications, including two-way radio
systems, microwave, fiber optics, wireless cable and paging and rooftop
infrastructure construction services. ATC manages approximately 600 towers (of
which approximately 400 are rooftop towers). Management contracts are
generally for a period of five years and contain automatic five-year renewal
periods unless terminated by either party before renewal or upon an uncured
default. Under these contracts, ATC is responsible for marketing antennae
sites on the tower, reviewing existing and negotiating future license
agreements with tenant users, managing and enforcing those agreements,
supervising installation of equipment by tenants to ensure, among other
things, non-interference with other users, supervising repairs and maintenance
to the towers, as well as site billing, collections and contract
administration. In addition, ATC handles all calls as well as questions
regarding the site so that the building management team or owner is relieved
of this responsibility. For such services, ATC is entitled to a percentage of
lease payments, which is higher for new tenants than for existing tenants.
Upon any termination of a contract, unless because of its default, ATC is
generally entitled to its percentage with respect to then existing tenants so
long as they remain tenants.
 
Services Segment
 
  Site Acquisition Business/Construction. ATC's site acquisition division has
developed more than 8,000 sites in 48 states and currently has field offices
in 13 major cities, including Atlanta, Chicago, Charlotte, Cleveland,
Jacksonville, New Orleans and Seattle. The site selection and acquisition
process begins with the network design. Highway corridors, population centers
and topographical features are identified within the carrier's existing or
proposed network, and drive tests are performed to monitor all PCS, cellular
and ESMR frequencies to locate the systems then operating in that geographic
area and identify where any holes in coverage may exist. Based on this data,
the carrier and ATC develop a "search ring", generally of one-mile radius,
within which the site acquisition department identifies land available either
for purchase or lease. ATC personnel select the most suitable sites, based on
demographics, traffic patterns and signal characteristics. The site is then
submitted to the local zoning/planning board for approval. If the site is
approved, in certain instances ATC will supervise construction of the towers
and other improvements on the communications site. ATC's site acquisition
services are provided on a fixed fee or time and materials basis. Existing
users of ATC's site acquisition services include Airtouch, Alltel, AT&T
Wireless, Ameritech, Bell Atlantic Mobile, BellSouth, GTE Mobilnet,
MobileComm, PageNet, Power Tel, SkyTel, Southwestern Bell, Sprint PCS and
Western Wireless. While ATC will continue to provide site acquisition services
to those customers desiring them, it also intends to actively market its
construction services as an extension of these services.
 
  Build to Suit Business/Construction. Upon the closing of the OmniAmerica
merger, as described in the Notes to Consolidated Financial Statements, ATC
entered the tower construction business as an erector and now designs, builds,
installs, modifies and maintains land-based wireless communications
transmitting and receiving facilities primarily for providers of wireless
communications services. Prior to the merger, ATC had not itself constructed
towers, but rather managed the construction activities of independent third
parties. ATC also provides certain electrical engineering services, wireless
equipment testing services and site acquisition and evaluation services in
connection with the location and installation of wireless communications
facilities.
 
                                       8
<PAGE>
 
  Historically, cellular and other wireless service providers have constructed
a majority of their towers for their own use, while usually outsourcing
certain services such as site acquisition and construction management. More
recently, however, service providers have expressed a growing interest in
having independent companies own the towers on which they will secure space
under long-term leases. Management believes this trend is the result of a need
among such providers to preserve capital and to speed access to their markets
by focusing on activities that contribute to subscriber growth and by
outsourcing infrastructure requirements such as owning, constructing and
maintaining towers or by co-locating their transmission infrastructure. ATC
has positioned itself as an attractive choice for this build to suit
opportunity. It has done so by acquiring and developing reputable site
acquisition companies with established client relationships in both site
acquisition and construction management, and by obtaining the financial
resources necessary to participate in the build to suit arena on a substantial
scale. Management believes companies that are able to demonstrate the ability
to successfully locate, acquire and permit sites and finance and construct
towers in a timely manner will be used by a significant number of wireless
service providers on an expanded basis. ATC is currently engaged in build to
suit efforts for a number of wireless service providers. It is also seeking
several major build to suit projects, although no definitive agreements may
result.
 
  The cost of construction of a tower varies both by site location (which will
determine, among other things, the required height of the tower) and type of
tower. Non-broadcast towers (whether on a rooftop or the ground) generally
cost between approximately $150,000 and $200,000. Broadcasting towers
generally are built to bear a greater load and usually cost between $300,000
and $1.0 million if on an elevated location and between $1.0 million and $3.5
million if on flat terrain.
 
  The number of antennae that ATC's towers can accommodate varies depending on
the type of tower (broadcast or non-broadcast), and the tower's location,
height and the loaded capacity at certain wind speeds. An antenna's height on
a tower and such tower's location determine the line-of-sight of such antenna
with the horizon and, consequently, the distance a signal can be transmitted.
Some users, such as paging companies and SMR providers in rural areas, need
higher elevations for broader coverage. Other carriers such as PCS, ESMR and
cellular companies in metropolitan areas usually do not need to place their
equipment at the highest tower point. Non-broadcast towers of 200-300 feet
that are designed to maximize capacity generally are capable of housing
between five and ten tenants using an aggregate of between 25 and 50 antennae.
Broadcasting towers generally are capable of housing between ten and forty
tenants using an aggregate of between 50 and 100 antennae. In most cases, well
engineered and well located towers built to serve the specifications of an
initial anchor tenant in the wireless communications sector will attract three
or more additional wireless tenants over time, thereby increasing revenue and
enhancing margins.
 
  ATC also provides some additional services which were not significant to its
overall operations in 1998. ATC manufactures and sells a line of fasteners and
other mounting components, waveguide bridge products, square support rail,
tower lighting systems, tower safety products and other hardware products. End
users utilize these products primarily in connection with the installation and
maintenance of wireless communications facilities. ATC also manufactures
certain wireless components on a private label basis for sale to several large
wireless communications equipment vendors who market these products under
their own brand names. In addition, ATC provides tower site monitoring
services to notify and alert tower owners, the FAA, utility companies or
others of problems or irregular conditions at ATC and third party tower sites.
 
Video, Voice, Data and Internet Transmission Services Segment
 
  ATC's video, voice, data and Internet transmission business is called ATC
Teleports. It is operated in and between New York City and Washington, D.C.
and throughout Texas. A teleport is a hub for transmissions to and from ground
based sources and satellites. A typical teleport facility consists of
satellite antennas (dishes), a 24-hour, 365-day operations center, terrestrial
links and other support facilities. ATC owns a teleport outside of New York
City and one outside of Washington, D.C. It also has a terrestrial system
connecting Washington, D.C., Baltimore, Philadelphia and New York City. The
New York teleport system is located on a 70-acre owned site which is zoned for
29 satellite dishes of which 22 are existing, thereby providing significant
expansion
 
                                       9
<PAGE>
 
capacity. The Washington, D.C. teleport is located in northern Virginia,
inside of the Washington Beltway, on 16 acres and has 40 dishes with the
capacity for an additional 20. The terrestrial system between the teleports
consists of fiber and microwave channels. The entire system is used by
television networks, broadcasters, cable programmers, and many of the leading
voice, data and Internet providers. The teleports can access all of the
domestic and major international satellites in their operating regions. The
Texas system consists of a teleport outside of Dallas and a terrestrial system
connecting Dallas, Austin, San Antonio, Houston and Corpus Christi. The system
connects to all major sports and convention venues, broadcasters and other
significant video users in Texas.
 
Customers
 
  ATC's customers aggregate approximately 3,900 and include many of the major
companies in the wireless communications industry. While none of ATC's
customers accounted for as much as 10% of its operating revenues for the year
ended December 31, 1998, most of the customers named below account for more
than 1% of such revenues, and each is considered by ATC to be an important
customer:
 
  .  Cellular and PCS: Airtouch, Alltell, AT&T Wireless, Bell Atlantic
     Mobile, BellSouth, GTE Mobilnet, Houston Cellular, Mobile Comm,
     Omnipoint, PacBell, PrimeCo PCS, Southwestern Bell Mobile Systems
     (operating as Cellular One), and Sprint PCS;
 
  .  Paging: Arch, Metrocall, PageMart, PageNet and Pittencrief;
 
  .  ESMR: Nextel; and
 
  .  Television and Radio Broadcasting: ABC, CBS, Chancellor Media, Clear
     Channel, CNN, Fox and NBC.
 
  ATC's site acquisition services, which afford ATC the opportunity to furnish
additional services such as the construction and zoning of communications
sites, are provided to most of the cellular, PCS and ESMR customers listed
above. ATC has constructed or is constructing towers on a build to suit basis
for companies such as BellSouth, Nextel, Omnipoint, PrimeCo PCS and
Southwestern Bell and is seeking several major build to suit projects,
although no definitive agreements may result.
 
  The principal users of ATC's video, voice, data and Internet transmission
services are television broadcasters and other video suppliers, such as CBS,
CNN, Fox and TCI. Revenues are derived from two sources of approximately equal
significance: (i) contracted, long-term services of a regular, recurring
nature and (ii) nonrecurring services relating to special news or events.
 
Management Organization
 
  ATC is headquartered in Boston, Massachusetts and is organized on a regional
basis with each region being headed by a vice president who reports to the
Chief Operating Officer. Its current regional operations are based in Boston,
Albuquerque, Atlanta, Chicago, Houston and the San Francisco Bay area,
although additional regional centers may develop over time. Management
believes that its regional operations centers which are in varying stages of
development should ultimately be capable of responding effectively to the
opportunities and customer needs of their respective defined geographic areas
and that these operations centers should have skilled engineering,
construction management and marketing personnel. Management also believes that
over time enhanced customer service and greater operating efficiencies can be
achieved by centralizing certain operating functions, including accounting and
lease administration. Such centralization, when achieved, will enable key
information about each site, tower lease and customer to become part of a
centralized database, with communication links to regional operations centers.
 
  In conjunction with its acquisition of various companies, management
believes it has obtained the services of key personnel with skills in areas
such as site acquisition, construction management, tower operations,
engineering, marketing, lease administration and finance. As ATC seeks to
expand its size and improve on the
 
                                      10
<PAGE>
 
quality and consistency of service delivery, it will need to complete the
staffing of its existing regions and may, in the longer term, need to
supplement its current workforce in certain critical areas, develop new
regional centers and intensify its dedication to customer service.
Accordingly, management is actively recruiting key personnel to complete the
staffing of its regional operations centers and to strengthen and deepen its
corporate group. ATC focuses its efforts on recruiting people from the
industry sectors it serves and in some instances recruiting skilled
engineering, marketing and other personnel from outside the communications
site, wireless communications and broadcasting industries.
 
History and ATC Formation
 
  In early 1995, Steven B. Dodge, the then Chairman of the Board, President
and Chief Executive Officer of American Radio Systems Corporation ("American
Radio" or "ARS"), and other members of its management, recognized the
opportunity in the communications site industry as a consequence of its
ownership and operation of broadcast towers. As a result, ATC was formed and
incorporated in Delaware in July 1995 as a subsidiary of American Radio to
capitalize on this opportunity. American Radio distributed its ATC stock to
its securityholders in connection with its merger with CBS Corporation ("CBS")
in June 1998. For further information see "ATC Separation" below and the Notes
to Consolidated Financial Statements.
 
 ATC Separation.
 
  On June 4, 1998, American Radio consummated its merger with CBS and American
Tower ceased to be a subsidiary of, or otherwise affiliated with, American
Radio and commenced operations as an independent publicly traded company (the
"ATC Separation"). As part of the ATC Separation, all of the common stock of
American Tower owned by American Radio was distributed to ARS common
stockholders and holders of options to acquire ARS common stock and were or
will be distributed upon conversion of American Radio convertible securities.
As required by the CBS-ARS merger, ATC entered into an agreement (the
"Separation Agreement") with CBS and American Radio providing for, among other
things, the allocation of certain tax liabilities to American Tower, certain
closing date adjustments relating to American Radio, the lease to American
Radio by American Tower of space on certain towers previously owned by
American Radio and transferred to ATC, and the orderly separation of American
Radio and ATC. For information concerning the amounts heretofore paid by ATC
to CBS pursuant to such provisions, and ATC's remaining obligations with
respect to those tax liabilities, see "Management's Discussion and Analysis of
Financial Condition and Results of Operations--Liquidity and Capital
Resources--ATC Separation" under Item 7 and the Notes to Consolidated
Financial Statements.
 
Recent Transactions
 
 Consummated Acquisitions.
 
  During the period January 1, 1998 through March 4, 1999, ATC has acquired
various communications sites and businesses for an estimated purchase price of
approximately $1.6 billion, including the issuance of approximately
57.0 million shares of Class A common stock valued (at the time of the
relevant agreement) at $837.4 million. The most significant of those
acquisitions are described in the Notes to Consolidated Financial Statements.
 
 Pending Acquisitions.
 
  ATC is a party to various agreements relating to the acquisition and
construction of additional towers for third parties which involve an aggregate
purchase price (a portion of which is payable in shares of Class A common
stock) of between $6.0 million and $30.0 million, depending on the cash flow
of the towers to be acquired and the actual number of towers to be built. Such
transactions are subject to the satisfaction of customary closing conditions
and, in certain cases, the expiration or earlier termination of the Hart-Scott
Rodino ("HSR") Act waiting period and most are scheduled to close in the
spring or summer of 1999.
 
                                      11
<PAGE>
 
Regulatory Matters
 
  Federal Regulations. Both the FCC and the FAA regulate towers used for
wireless communications and radio and television antennae. Such regulations
control the siting, lighting, marking and maintenance of towers and may,
depending on the characteristics of the tower, require registration of tower
facilities and issuance of determinations of no hazard. Wireless
communications devices operating on towers are separately regulated and
independently licensed by the FCC based upon the regulation of the particular
frequency used. In addition, the FCC also separately licenses and regulates
television and radio stations broadcasting from towers. Depending on the
height and location, proposals to construct new antenna structures or to
modify existing antenna structures are reviewed by the FAA to ensure that the
structure will not present a hazard to aircraft, and such review is a
prerequisite to FCC authorization of communications devices placed on the
tower. Tower owners also bear the responsibility for notifying the FAA of any
tower lighting failures. Year 2000-related problems could cause ATC's tower
light systems to fail which would create a hazard to air navigation. See
"Management's Discussion and Analysis of Financial Condition and Results of
Operations--Year 2000" under Item 7. ATC generally indemnifies its customers
against any failure to comply with applicable standards. Failure to comply
with applicable requirements may lead to civil penalties.
 
  The introduction and development of digital television also may affect ATC
and some of its largest customers. In addition, the need to install additional
antennae required to deliver digital television service may necessitate the
relocation of many currently co-located FM antennae. The need to secure state
and local regulatory approvals for the construction and reconstruction of this
substantial number of antennae and the structures on which they are mounted
presents a potentially significant regulatory obstacle to the communications
site industry. As a result, the FCC has solicited comments on whether, and in
what circumstances, the FCC should preempt state and local zoning and land use
laws and ordinances regulating the placement and construction of
communications sites. There can be no assurance as to whether or when any such
federal preemptive regulations may be promulgated or, if adopted, what form
they might take, whether they would be more or less restrictive than existing
state and local regulations, or whether the constitutionality of such
regulation, if challenged on constitutional grounds, would be upheld.
 
  Local Regulations. Local regulations include city and other local
ordinances, zoning restrictions and restrictive covenants imposed by local
authorities. These regulations vary greatly, but typically require tower
owners to obtain approval from local officials or community standard
organizations prior to tower construction. Local regulations can delay or
prevent new tower construction or site upgrade projects, thereby limiting
ATC's ability to respond to customer demand. In addition, such regulations
increase costs associated with new tower construction. Existing regulatory
policies may adversely affect the timing or cost of new tower construction and
additional regulations may be adopted which increase such delays or result in
additional costs to ATC. Such factors could have a material adverse effect on
ATC's financial condition or results of operations.
 
  Other. ATC's customers may also become subject to new regulations or
regulatory policies which adversely affect the demand for communication sites.
In addition, if ATC pursues international opportunities, it will be subject to
regulations in foreign jurisdictions.
 
Environmental and Health Matters
 
  Under various federal, state and local environmental laws, ordinances and
regulations, an owner of real estate or a lessee conducting operations thereon
may become liable for the costs of investigation, removal or remediation of
soil and groundwater contaminated by certain hazardous substances or wastes.
Certain of such laws impose cleanup responsibility and liability without
regard to whether the owner or operator of the real estate or operations
thereon knew of or was responsible for the contamination, and whether or not
operations at the property have been discontinued or title to the property has
been transferred. The owner or operator of contaminated real estate also may
be subject to common law claims by third parties based on damages and costs
resulting from off-site migration of the contamination. In connection with its
former and current ownership or operation of its properties, ATC may be
potentially liable for environmental costs such as those discussed above.
 
                                      12
<PAGE>
 
  ATC believes it is in compliance in all material respects with all
applicable material environmental laws. ATC has not received any written
notice from any governmental authority or third party asserting, and is not
otherwise aware of, any material environmental non-compliance, liability or
claim relating to hazardous substances or wastes or material environmental
laws. However, (i) undetected environmental conditions may exist for which ATC
might be liable in the future and (ii) future regulatory action, as well as
compliance with future environmental laws, may require ATC to incur costs that
could have a material adverse effect on ATC's financial condition and results
of operations.
 
  ATC and the lessees of antennae sites on its towers are subject to
government regulations relating to radio frequency emissions. In recent years,
there have been several substantial studies by the scientific community
investigating the potential connection between radio frequency emissions and
possible negative health effects, including cancer. The results of these
studies have, to date, been inconclusive. ATC has not been subject to any
claims relating to these emissions, although it is possible that such claims
may arise in the future. Because ATC does not maintain any significant
insurance with respect to such matters, such claims, if substantiated, could
have a material adverse effect on ATC.
 
Competition; New Technologies
 
  ATC competes for antennae site customers with wireless carriers that own and
operate their own tower networks and lease tower space to other carriers, site
development companies that acquire space on existing towers for wireless
service providers and manage new tower construction, other national
independent tower companies and traditional local independent tower operators.
Wireless service providers that own and operate their own tower networks
generally are substantially larger and have greater financial and other
resources than ATC. ATC believes that tower location and capacity, price,
quality of service and density within a geographic market historically have
been and will continue to be the most significant competitive factors
affecting owners, operators and managers of communications sites.
 
  ATC faces strong competition for build to suit opportunities, particularly
those with wireless service providers seeking to divest their ownership of
towers, principally from other independent communications site operators and
site developers. ATC expects such competition to intensify and believes that
the terms of such transactions may become significantly less favorable to it
and other independent tower owners as a consequence.
 
  ATC competes for tower and site acquisitions principally with other
independent tower owners and operators. Increased competition may intensify
and result in substantially higher prices, particularly for towers being
divested by wireless service providers. ATC may not, therefore, be able to
complete acquisitions on as favorable terms as in the past. Under certain
circumstances, it may also be required to pay higher prices or agree to less
favorable terms than it would otherwise have desired. American Tower may also
be impeded in its future acquisition activities by antitrust constraints,
either in local markets or on a regional or national basis.
 
  The emergence of new technologies could reduce the need for tower-based
transmission and reception and may, thereby, have a negative impact on ATC's
operations. For example, the FCC has granted license applications for several
low-earth orbiting satellite systems that are intended to provide mobile voice
and/or data services. In November 1998, a company became the first to offer
commercially a service intended to provide global satellite phone coverage.
Although such systems are highly capital-intensive and do not yet have an
extensive commercial record, mobile satellite systems could compete with land-
based wireless communications systems, thereby reducing the demand for the
infrastructure services provided by ATC. Additionally, the growth in delivery
of video services by direct broadcast satellites and the development and
implementation of signal combining technologies (which permit one antenna to
service two different frequencies of transmission and, thereby, two customers)
and satellite-delivery systems may reduce the need for tower-based broadcast
transmission.
 
                                      13
<PAGE>
 
Manufacturing and Raw Materials
 
  American Tower builds, maintains and installs land based wireless
communication transmitting and receiving facilities by obtaining sheet metal
and other raw material parts and components from a variety of vendors. The
Company also engages third party contract manufacturers to produce certain of
these wireless transmitting and receiving facilities. The Company has
historically obtained the majority of its sheet metal and other raw materials
from a limited number of suppliers; however, substantially all of these items
are available from numerous other suppliers. ATC has not, to date, experienced
any significant difficulties in obtaining the needed quantities of materials
from suppliers in a timely manner.
 
Employees
 
  As of March 1, 1999, ATC employed approximately 975 full time individuals
and considers its employee relations to be satisfactory.
 
ITEM 2. PROPERTIES.
 
  The Company leases approximately 8,400 square feet of space at 116
Huntington Avenue, Boston, Massachusetts, which it uses for its corporate
headquarters. In addition the Company also leases additional space in Boston,
Albuquerque, Atlanta, Chicago, Houston and San Francisco which function as
regional operating centers.
 
  ATC's interests in its communications sites are comprised of a variety of
fee interests, leasehold interests created by long-term lease agreements,
private easements and easements, licenses or rights-of-way granted by
government entities. In rural areas, a communications site typically consists
of a three-to five-acre tract which supports towers, equipment shelters and
guy wires to stabilize the structure. Less than 2,500 square feet are required
for a self-supporting tower structure of the kind typically used in
metropolitan areas. Land leases generally have twenty (20) to twenty-five (25)
year terms, with three five-year renewals, or are for five-year terms with
automatic renewals unless ATC otherwise specifies. ATC has more than 2,000
land leases. Pursuant to the Credit Facilities, the senior lenders have liens
on, among other things, all leases of tower space, contracts relating to the
management of towers for others, cash, accounts receivable, the stock and
inter-company debt of all Restricted Subsidiaries (as defined in the Credit
Facilities), inventory and other personal property, fixtures, intellectual
property, as well as certain fee and leasehold interests, and the proceeds
thereof of ATC and its Restricted Subsidiaries.
 
ITEM 3. LEGAL PROCEEDINGS.
 
  ATC is involved in legal proceedings that arise in the ordinary course of
business. While the outcome of these proceedings cannot be predicted with
certainty, management, after consultation with counsel, does not expect any
pending matters to have a material adverse effect on ATC's financial position,
liquidity or results of operations.
 
ITEM 4. SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS.
 
  No matters were submitted to a vote of the security holders of ATC in the
fourth quarter of 1998.
 
ITEM 5. MARKET FOR REGISTRANT'S COMMON EQUITY AND RELATED STOCKHOLDER MATTERS.
 
Market Price Data
 
  On February 27, 1998, the Class A common stock commenced trading on a "when-
issued" basis on the inter-dealer bulletin board of the over-the-counter
market. The Class A common stock commenced trading under the symbol AMT on the
New York Stock Exchange (NYSE) on June 5, 1998 (the day after ATC separated
from
 
                                      14
<PAGE>
 
American Radio). The following table presents trading information for the
Class A common stock for the periods indicated, in such "when issued" market
or, since June 5, 1998, on the NYSE.
 
<TABLE>
<CAPTION>
   1998                                                          High     Low
   ----                                                         ------- -------
   <S>                                                          <C>     <C>
   Quarter Ended March 31 (commencing February 27, 1998)....... $ 20.25 $ 15.50
   Quarter Ended June 30.......................................  26.125   18.75
   Quarter Ended September 30..................................  28.625  14.375
   Quarter Ended December 31...................................  29.625   13.25
</TABLE>
 
  As of March 15, 1999, there were 394 record holders of the Class A common
stock, 75 record holders of the Class B common stock and one record holder of
the Class C common stock.
 
  ATC has not paid a dividend on any class of common stock and anticipates
that it will retain future earnings, if any, to fund the development and
growth of its business. It does not anticipate paying cash dividends on shares
of common stock in the foreseeable future. In addition, substantially all of
ATC's subsidiaries are restricted under the Credit Facilities from paying
dividends or making distributions and repurchasing, redeeming or otherwise
acquiring any shares of common stock. Since ATC has no significant assets
other than its ownership of various subsidiaries, substantially all of which
are so restricted, its ability to pay cash dividends in the foreseeable future
is restricted. The Credit Facilities also restrict the payment of cash
dividends by ATC. See "Management's Discussion and Analysis of Financial
Condition and Results of Operations--Liquidity and Capital Resources" and
Notes to Consolidated Financial Statements.
 
Recent Sales of Unregistered Securities.
 
  Pursuant to the American Tower Systems Corporation Stock Purchase Agreement,
dated as of January 8, 1998, by and among ATC and the Purchasers thereto, ATC
consummated an equity financing involving the issuance of an aggregate of
1,350,050 shares of Class A common stock, 4,649,950 shares of Class B common
stock and 2,000,000 shares of Class C common stock, each at $10.00 per share,
in exchange for $30.6 million in cash and $49.4 million of notes secured by
common stock of American Radio having a market value of not less than 175% of
the principal amount and accrued and unpaid interest on such notes.
 
  Pursuant to the Agreement and Plan of Merger, dated as of November 21, 1997,
as amended, by and among ATC, American Tower Systems, Inc., a Delaware
corporation (now known as American Towers, Inc., "ATI"), Gearon & Co., Inc., a
Georgia corporation ("Gearon") and J. Michael Gearon, Jr., pursuant to which
Gearon was merged with and into ATI, with ATI as the surviving corporation, in
January 1998 ATC issued an aggregate of 5,333,333 shares of Class A common
stock and paid approximately $32.0 million in cash or assumed liabilities for
an aggregate agreed upon consideration of approximately $80.0 million.
 
  On June 4, 1998, ATC issued in a private placement to institutional
investors 300,000 shares of Series A Pay-In-Kind Preferred Stock, $1,000
liquidation preference per share, ("Interim Preferred Stock") pursuant to the
Securities Purchase Agreement, dated as of June 4, 1998, by and among ATC,
Credit Suisse First Boston Corporation and each of the purchasers named
therein.
 
  Pursuant to the Agreement and Plan of Merger, dated as of April 14, 1998, by
and among ATC, ATI, Intracoastal Broadcasting, Inc. ("Intracoastal") and the
stockholders of Intracoastal, pursuant to which Intracoastal was merged with
and into ATI, with ATI as the surviving corporation, in June 1998, ATC issued
an aggregate of 720,000 shares of Class A common stock.
 
  Pursuant to the Agreement and Plan of Merger, dated as of October 16, 1998,
by and among ATC, ATI and Wauka Communications, Inc. ("Wauka"), pursuant to
which Wauka was merged with and into ATI, with ATI as the surviving
corporation. In October 1998, ATC issued an aggregate of 1,430,881 shares of
Class A common stock as part of the consideration in the merger.
 
  All of the shares referred to in the foregoing paragraphs were issued by ATC
in reliance on the exemption from registration provided by Section 4(2) of the
Securities Act of 1933, as amended (the "Securities Act").
 
                                      15
<PAGE>
 
Each holder represented that it was acquiring its shares for investment
purposes and not with a view to distribution within the meaning of the
Securities Act. The stock certificates issued to all such holders bore
restrictive legends. No commission or other remuneration will be paid or given
by ATC directly or indirectly in connection with any of the foregoing
transactions.
 
ITEM 6. SELECTED FINANCIAL DATA
 
  The financial data set forth below has been derived from the audited
consolidated financial statements of ATC, certain of which are included in
this Annual Report on Form 10-K. The data should be read in conjunction with
ATC's audited consolidated financial statements and with "Management's
Discussion and Analysis of Financial Condition and Results of Operations".
Prior to the ATC Separation on June 4, 1998, ATC operated as a subsidiary of
American Radio and not as an independent public company. Therefore, the
results of operations and the financial condition shown below for such period
may be different from what they might have been had ATC operated as a
separate, independent public company. The information is also not necessarily
indicative of ATC's future results of operations or financial condition.
 
                                      16
<PAGE>
 
                          SELECTED FINANCIAL DATA (1)
                     (In thousands, except per share data)
 
<TABLE>
<CAPTION>
                               Year Ended December 31,         July 17, 1995
                             -----------------------------        through
                                1998       1997     1996    December 31, 1995(1)
                             ----------  --------  -------  --------------------
<S>                          <C>         <C>       <C>      <C>
Statement of Operations
 Data:
Operating revenues.........  $  103,544  $ 17,508  $ 2,897         $  163
                             ----------  --------  -------         ------
Operating expenses:
  Operating expenses
   excluding depreciation
   and amortization, tower
   separation expenses and
   corporate general and
   administrative
   expenses................      61,751     8,713    1,362             60
  Depreciation and
   amortization............      52,064     6,326      990             57
  Tower separation
   expenses................      12,772
  Corporate general and
   administrative
   expenses................       5,099     1,536      830            230
                             ----------  --------  -------         ------
    Total operating
     expenses..............     131,686    16,575    3,182            347
                             ----------  --------  -------         ------
(Loss) income from
 operations................     (28,142)      933     (285)          (184)
Interest expense...........     (23,229)   (3,040)
Interest income and other,
 net.......................       9,217       251       36
Minority interest in net
 earnings of subsidiaries..        (287)     (193)    (185)
                             ----------  --------  -------         ------
Loss before benefit
 (provision) for income
 taxes and extraordinary
 losses....................     (42,441)   (2,049)    (434)          (184)
Benefit (provision) for
 income taxes..............       4,491       473      (45)            74
                             ----------  --------  -------         ------
Loss before extraordinary
 losses....................  $  (37,950) $ (1,576) $  (479)        $ (110)
                             ==========  ========  =======         ======
Basic and diluted loss per
 common share before
 extraordinary losses(2)...  $    (0.48) $  (0.03) $ (0.00)        $(0.00)
                             ==========  ========  =======         ======
Basic and diluted common
 shares outstanding(2).....      79,786    48,732   48,732         48,732
                             ==========  ========  =======         ======
Other Operating Data:
Tower cash flow(3).........  $   41,793  $  8,795  $ 1,535         $  103
EBITDA(3)..................      36,694     7,259      705           (127)
EBITDA margin..............        35.4%     41.5%    24.3%          (N/A)
After-tax cash flow(3).....      14,114     4,750      511            (53)
Balance Sheet Data:
Cash and cash equivalents..  $  186,175  $  4,596  $ 2,373         $   12
Working capital
 (deficiency), excluding
 current portion of long-
 term debt.................      93,602    (2,208)     663            (40)
Property and equipment,
 net.......................     449,476   117,618   19,710          3,759
Total assets...............   1,502,343   255,357   37,118          3,863
Long-term debt, including
 current portion...........     281,129    90,176    4,535            --
Total stockholders'
 equity....................   1,091,746   153,208   29,728          3,769
</TABLE>
- --------
(1) American Towers, Inc., a wholly-owned subsidiary of ATC, was organized on
    July 17, 1995 and American Radio contributed all of the issued and
    outstanding capital stock of ATI to ATC on September 24, 1996. The timing
    of acquisitions of communications sites and related businesses and
    construction of towers, both of which have been numerous during the
    period, significantly affect year-to-year comparisons. The principal
    acquisitions made in 1997 and 1998 are described in the Notes to
    Consolidated Financial Statements.
 
                                      17
<PAGE>
 
(2) Basic and diluted loss per share has been computed using the weighted
    average number of shares outstanding during each period presented. Shares
    outstanding upon consummation of the ATC Separation are assumed to be
    outstanding for the entire periods prior to June 4, 1998. Shares issuable
    upon exercise of options have been excluded from the computations as the
    effect is anti-dilutive.
(3) We use the term "Tower Cash Flow" to mean operating income before
    depreciation and amortization, corporate general and administrative
    expenses and tower separation expenses . "EBITDA" is used by us to mean
    operating income before depreciation and amortization and tower separation
    expenses. "After-tax cash flow" means income (loss) before extraordinary
    items, plus depreciation and amortization, less preferred stock dividends.
    We do not consider Tower Cash Flow, EBITDA and after-tax cash flow as a
    substitute for alternative measures of operating results or cash flow from
    operating activities or as a measure of ATC's profitability or liquidity.
    Although these measures of performance are not calculated in accordance
    with generally accepted accounting principles ("GAAP"), we have included
    them because they are generally used in the communications site industry
    as a measure of a company's operating performance. More specifically, we
    believe they can assist in comparing company performances on a consistent
    basis without regard to depreciation and amortization. The concern is that
    depreciation and amortization can vary significantly among companies
    depending on accounting methods, particularly where acquisitions are
    involved, or non-operating factors such as historical cost bases. We
    believe Tower Cash Flow is useful because it enables you to compare tower
    performances before the effect of expenses (corporate general and
    administrative) that do not relate directly to such performance.
 
ITEM 7. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND
RESULTS OF OPERATIONS.
 
General
 
  This discussion contains "forward-looking statements", including statements
concerning projections, plans, objectives, future events or performance and
underlying assumptions and other statements which are other than statements of
historical fact. Various factors affect ATC's results and could cause ATC's
actual results to differ materially from those expressed in any forward-
looking statement. Such factors include:
 
  .  the outcome of our growth strategy,
 
  .  future results of operations,
 
  .  liquidity and capital expenditures,
 
  .  construction and acquisition activities,
 
  .  debt levels and the ability to obtain financing and service debt,
 
  .  competitive conditions in the communications site and wireless carrier
     industries,
 
  .  regulatory developments in the communications site and wireless carrier
     industries,
 
  .  projected growth of the wireless communications and wireless carrier
     industries, and
 
  .  general economic conditions.
 
  As ATC was a wholly-owned subsidiary of American Radio during the periods
presented through June 4, 1998, the consolidated financial statements may not
reflect the results of operations or financial position of ATC had it been an
independent public company during those periods. Because of ATC's relatively
brief operating history and the large number of recent acquisitions, the
following discussion will not necessarily reveal all significant developing or
continuing trends.
 
  In June 1998, ATC became an independent public company when its parent,
American Radio, distributed all of the ATC common stock held by it to American
Radio's securityholders in connection with the ATC
 
                                      18
<PAGE>
 
Separation and merged and became a subsidiary of CBS. ATC remains liable to
pay CBS amounts relating to American Radio's tax obligations in the ATC
Separation. See the Notes to Consolidated Financial Statements.
 
  ATC was formed in July 1995 to capitalize on the opportunity in the
communications site industry. ATC is a leading independent owner and operator
of wireless communications towers in the United States. During 1997, its
acquisition and construction activity accelerated and ATC acquired or
constructed approximately 400 sites (and related site management businesses)
and its initial site acquisition and voice, video, data and Internet
transmission businesses. During the year ended December 31, 1998, the Company
acquired various communications sites and businesses for an aggregate
preliminary purchase price of approximately $853.8 million, including the
issuance of approximately 36.3 million shares of Class A common stock valued
at approximately $382.6 million. Since January 1, 1999, ATC has acquired
various communications sites and businesses for an aggregate estimated
purchase price of approximately $746.0 million, including the issuance of
approximately 20.7 million shares of Class A common stock valued (at the time
of the relevant agreement) at approximately $454.8 million.
 
  Management expects that acquisitions consummated to date will have a
material impact on future revenues, expenses and income from operations. In
addition, the historical financial information presented below and elsewhere
in this Annual Report on Form 10-K does not reflect the impact of the
construction program of ATC to any significant extent because most of that
activity is of more recent origin and is expected to accelerate substantially
during 1999.
 
Results of Operations
 
Year Ended December 31, 1998 and 1997 (in thousands)
 
  As of December 31, 1998, ATC operated approximately 2,300 communications
sites, as compared to approximately 700 communications sites as of December
31, 1997. The acquisitions reflected in such growth have significantly
affected operations for the year ended December 31, 1998 as compared to the
year ended December 31, 1997. See the Notes to Consolidated Financial
Statements for a description of the acquisitions consummated in 1998 and 1997.
<TABLE>
<CAPTION>
                                                     Year Ended
                                                    December 31,     Amount of
                                                  -----------------   Increase
                                                    1998     1997    (Decrease)
                                                  --------  -------  ----------
<S>                                               <C>       <C>      <C>
Tower rental and management revenues............. $ 60,505  $13,302   $ 47,203
Services revenues................................   23,315    2,122     21,193
Video, voice, data and Internet transmission
 revenues........................................   19,724    2,084     17,640
                                                  --------  -------   --------
Total operating revenues.........................  103,544   17,508     86,036
                                                  --------  -------   --------
Tower rental and management expenses.............   29,455    6,080     23,375
Services expenses................................   19,479    1,360     18,119
Video, voice, data and Internet transmission
 expenses........................................   12,817    1,273     11,544
                                                  --------  -------   --------
Total operating expenses excluding depreciation
 and amortization, tower separation expenses and
 corporate general and administrative expenses...   61,751    8,713     53,038
                                                  --------  -------   --------
Depreciation and amortization....................   52,064    6,326     45,738
Tower separation expenses........................   12,772      --      12,772
Corporate general and administrative expenses....    5,099    1,536      3,563
Interest expense.................................   23,229    3,040     20,189
Interest income and other, net...................    9,217      251      8,966
Minority interest in net earnings of
 subsidiaries....................................      287      193         94
Income tax benefit...............................    4,491      473      4,018
Extraordinary loss on extinguishment of debt,
 net.............................................    1,382      694        688
Extraordinary loss on redemption of Interim
 Preferred Stock, net............................    7,510      --       7,510
                                                  --------  -------   --------
Net loss......................................... $(46,842) $(2,270)  $(44,572)
                                                  ========  =======   ========
Tower cash flow.................................. $ 41,793  $ 8,795   $ 32,998
                                                  ========  =======   ========
EBITDA........................................... $ 36,694  $ 7,259   $ 29,435
                                                  ========  =======   ========
</TABLE>
 
                                      19
<PAGE>
 
  As noted above, ATC consummated numerous acquisitions in 1998 and 1997, many
of which were of a material size. Except as explained below, substantially all
of the increases indicated in the above table were attributable to the impact
of these communications sites and related business acquisitions, principally
those that occurred in 1998.
 
  Tower rental and management revenues and expenses for the year ended
December 31, 1998 include the effects of numerous tower acquisitions which
occurred in 1998 and the impact of a full year of operations for the 1997
acquisitions. Tower rental revenues were also impacted by the effects of the
Company's ability to secure renewal options on long-term site leasing
contracts and obtain rent escalations.
 
  Services revenues and expenses for the year ended December 31, 1998 include
the operating results of the Gearon site acquisition business (January 1998)
and, to a lessor extent, the operating results of two similar businesses (May
1997). For the year ended December 31, 1997, the results included the
operating results from a site acquisition business acquired in May 1997.
 
  Video, voice, data and Internet transmission revenues and expenses for the
year ended December 31, 1998 include the operating results of ATC's first
business of this type which was acquired in October 1997 and a Washington,
D.C. area teleport business acquired in May 1998.
 
  The increase in depreciation and amortization was primarily attributable to
the increase in depreciable and amortizable assets resulting from the 1997 and
1998 acquisitions and, to a lesser extent, construction projects completed in
1998.
 
  The tower separation expenses relate primarily to one-time financial
advisory, legal, accounting and consent solicitation fees and other expenses
incurred in connection with the ATC Separation. The Company may incur
additional separation expenses, although, such costs are not expected to be
material to the Company's results of operations, liquidity or financial
position.
 
  The increase in corporate general and administrative expenses was primarily
attributable to the higher personnel costs associated with supporting ATC's
greater number of tower properties and growth strategy.
 
  The increase in interest expense related to higher borrowing levels which
were used to finance the 1998 and 1997 acquisitions and, to a lesser extent,
the 1998 construction projects.
 
  The increase in interest income is related to interest earned on invested
cash proceeds from ATC's initial underwritten public offering that occurred in
July 1998.
 
  The minority interest in net earnings of subsidiaries represents the
elimination of the minority stockholder's earnings of consolidated
subsidiaries. The increase is related to increased overall earnings of ATS
Needham, LLC, in which ATC held a 50.1% interest until October 1998 at which
time it was increased to 80%.
 
  The effective tax rate for the year ended December 31, 1998 was
approximately 11% compared to approximately 23% for the year ended December
31, 1997. The effective tax rate differs from the statutory rate due to the
effect of non-deductible items, principally amortization of goodwill, on
certain stock acquisitions for which ATC recorded no tax benefit.
 
  The extraordinary loss on the redemption of the Interim Preferred Stock was
incurred, net of an income tax benefit of $5.0 million, as a result of certain
commitment, deferred financing and redemption fees associated with the Interim
Preferred Stock that was redeemed in July 1998.
 
  The extraordinary loss on the extinguishment of debt was incurred, net of an
income tax benefit of $0.9 million as a result of the write-off of deferred
financing fees associated with ATC's previous credit agreements which was
refinanced in June 1998.
 
                                      20
<PAGE>
 
Year Ended December 31, 1997 and 1996 (in thousands)
 
  As of December 31, 1997, ATC operated approximately 700 communications
sites, as compared to approximately 300 communications sites as of December
31, 1996. See the Notes to Consolidated Financial Statements for a description
of the acquisitions consummated in 1997. These transactions have significantly
affected operations for the year ended December 31, 1997 as compared to the
year ended December 31, 1996.
 
<TABLE>
<CAPTION>
                                         Year Ended December 31,    Amount of
                                         -------------------------   Increase
                                             1997         1996      (Decrease)
                                         ------------  -----------  ----------
<S>                                      <C>           <C>          <C>
Tower rental and management revenues.... $     13,302  $     2,897   $10,405
Services revenues.......................        2,122                  2,122
Video, voice, data and Internet
 transmission revenues..................        2,084                  2,084
                                         ------------  -----------   -------
Total operating revenues................       17,508        2,897    14,611
                                         ------------  -----------   -------
Tower rental and management expenses....        6,080        1,362     4,718
Services expenses.......................        1,360                  1,360
Video, voice, data and Internet
 transmission expenses..................        1,273                  1,273
                                         ------------  -----------   -------
Total operating expenses excluding
 depreciation and amortization and
 corporate general and administrative
 expenses...............................        8,713        1,362     7,351
                                         ------------  -----------   -------
Depreciation and amortization...........        6,326          990     5,336
Corporate general and administrative
 expenses...............................        1,536          830       706
Interest expense .......................        3,040                  3,040
Interest income and other, net..........          251           36       215
Minority interest in net earnings of
 subsidiaries...........................          193          185         8
Income tax benefit (provision)..........          473          (45)      518
Extraordinary loss......................          694                    694
                                         ------------  -----------   -------
Net loss................................ $     (2,270) $      (479)  $(1,791)
                                         ============  ===========   =======
Tower cash flow......................... $      8,795  $     1,535   $ 7,260
                                         ============  ===========   =======
EBITDA.................................. $      7,259  $       705   $ 6,554
                                         ============  ===========   =======
</TABLE>
 
  As noted above, ATC consummated numerous acquisitions in 1997 and 1996, many
of which were of a material size. Except as explained below, substantially all
of the increases indicated in the above table were attributable to the impact
of these communications sites and related business acquisitions that occurred
in 1997.
 
  The increase in depreciation and amortization was primarily attributable to
the increase in depreciable and amortizable assets resulting from the 1997 and
1996 acquisitions and, to a substantially lesser extent, completed
construction projects.
 
  The increase in corporate general and administrative expense was primarily
attributable to the higher personnel costs associated with supporting ATC's
greater number of tower properties and growth strategy.
 
  The increase in interest expense relate to higher borrowing levels which
were used to finance the 1997 acquisitions and, to a substantially lesser
extent, the 1996 acquisitions.
 
  The minority interest in net earnings of subsidiary represents the
elimination of the minority stockholder's earnings of consolidated
subsidiaries. The increase is related to increased overall earnings of ATS
Needham, LLC, in which ATC held a 50.1% interest.
 
  The effective tax rate in 1997 was approximately 23%. The effective tax rate
is due to the effect of non-deductible items, principally amortization of
goodwill, on certain stock acquisitions. In 1996, ATC recorded a
 
                                      21
<PAGE>
 
tax provision of approximately $45,000 despite a loss before taxes of
approximately $434,000. This primarily resulted from non-deductible items,
principally amortization of goodwill for which no tax benefit was recorded.
 
  The extraordinary loss in 1997 of approximately $0.7 million net of tax,
represents the write-off of deferred financing fees associated with ATC's loan
agreement.
 
Liquidity and Capital Resources
 
  ATC's liquidity needs arise from its acquisition-related activities, debt
service, working capital and capital expenditures associated principally with
its construction program. As of December 31, 1998 the Company maintained
approximately $186.2 million in cash and cash equivalents, working capital of
approximately $92.0 million, and had approximately $100 million available
under its credit facilities. Historically, ATC has met its operational
liquidity needs with internally generated funds and has financed the
acquisition of tower related properties and its construction program,
including related working capital needs, with a combination of capital funds
from sales of its equity securities (including sales prior to the ATC
Separation to American Radio) and bank borrowings. For the year ended December
31, 1998, cash flows from operating activities were $18.4 million, as compared
to $9.9 million of cash flows from operating activities in 1997. The change is
primarily attributable to the favorable cash flow generated from consummated
acquisitions in 1997 and 1998.
 
  For the year ended December 31, 1998 cash flows used for investing
activities were $350.4 million as compared to $216.8 million for the year
ended December 31, 1997. The increase in 1998 is due to an increase in
property and equipment expenditures of approximately $105.8 million coupled
with the increase in mergers and acquisitions during 1998 of approximately
$24.6 million.
 
  For the year ended December 31, 1998 cash flows provided by financing
activities were $513.5 million as compared to $209.1 million for the year
ended December 31, 1997. The increase in 1998 is due principally to the impact
of borrowings under ATC's credit arrangements, and the sale of common stock
pursuant to the Stock Purchase Agreement and the July Offering, offset by the
tax payments to CBS, all as discussed below.
 
  During the year ended December 31, 1998, ATC had capital expenditures of
approximately $126.5 million primarily related to construction activities and
completed construction on approximately 500 towers during this period. ATC's
1999 business plan calls for construction of between 1,200 and 1,600 towers at
a cost of between $216.0 million and $304.0 million (exclusive of broadcast
towers). The actual number of towers built may be outside of that range
because of more attractive investment opportunities from acquisitions (in
which case it could be less) or significant new build to suit projects with
wireless service providers (in which case it could be more). Management
believes that ATC has sufficient funds available to it to finance current
construction plans, pending acquisitions and several additional major
acquisitions and/or construction projects. However, in the unlikely event that
ATC were to negotiate more than a limited number of such major transactions,
it might require additional financing either through incurring additional debt
or the sale of securities. Such financing or sale of securities may not be
available on favorable terms.
 
  Management expects that the consummated acquisitions and current and future
construction activities will have a material impact on liquidity. Management
believes that the acquisition activities, once integrated, will have a
favorable impact on liquidity and will offset the initial effects of the
funding requirements. Management also believes that the construction
activities may initially have an adverse effect on the future liquidity of ATC
as newly constructed towers will initially decrease overall liquidity. But, as
such sites become fully operational and achieve higher utilization, they
should generate cash flow, and in the long-term, increase liquidity.
 
  Redeemable Common Stock: In June 1998, the Company merged with a company
owning a broadcasting tower in the Boston, Massachusetts area and issued
720,000 shares of Class A common stock valued at approximately $18.0 million
to close the transaction. In addition, under a put agreement that was
consummated in connection with the merger, the sellers have the right to
require the Company to purchase, at any time prior to June 5, 1999, any or all
shares of Class A common stock received pursuant to consummation of the merger
for a purchase price equal to the then current market price. In connection
with the July offering described below, the
 
                                      22
<PAGE>
 
sellers sold 383,750 of the 720,000 shares reducing the Company's overall
redemption obligation. Accordingly, the remaining 336,250 shares have been
recorded as redeemable Class A common stock in the consolidated financial
statements based on the December 31, 1998 fair market value of $29.5625 per
share.
 
  Credit Facilities: In June 1998, ATC and its subsidiaries entered into
definitive agreements with respect to new and increased credit arrangements.
In connection with repayment of borrowings under the prior credit agreement
out of proceeds of borrowings under the new credit agreements, ATC recognized
an extraordinary loss of approximately $1.4 million, net of a tax benefit of
$0.9 million, during the second quarter of 1998. As of December 31, 1998, ATC
had approximately $281.1 million of long-term debt, of which $275.0 million
was outstanding in the form of term loans and revolving credit facilities. See
Notes to the Consolidated Financial Statements for more information on the
credit facilities.
 
  Debt service requires a substantial portion of ATC's cash flow from
operations. Accordingly, ATC's leverage could make it vulnerable to a downturn
in the operating performance of its tower properties or in economic
conditions. ATC believes that its cash flows from operations will be
sufficient to meet its debt service requirements for interest and scheduled
payments of principal under the Credit Facilities. If such cash flow were not
sufficient to meet such debt service requirements, ATC might sell equity
securities, refinance its obligations or dispose of one or more of its
properties in order to make such scheduled payments. ATC may not be able to
effect any of such transactions on favorable terms. ATC believes that it has
sufficient financial resources available to it, including borrowings under its
credit facilities, to finance operations for the foreseeable future.
 
  ATC Separation: As part of the ATC Separation, ATC entered into an agreement
with CBS (the "Separation Agreement"). The Separation Agreement requires ATC
to reimburse CBS on a "make-whole" (after-tax) basis for the tax liabilities
incurred by ARS attributable to the distribution of the common stock owned by
ARS to its securityholders and certain related transactions, to the extent
that the aggregate amount of taxes required to be paid by ARS exceeded $20.0
million. The amount of that tax liability was dependent on the "fair market
value" of the common stock at the time of the consummation of the ATC
Separation. ATC received an appraisal from an independent appraisal firm that
the "fair market value" of ARS's stock interest in ATC was equal to $17.25 per
share. Based on such appraisal, ARS paid estimated taxes of approximately
$212.0 million, for which ATC reimbursed CBS. ATC's reimbursement obligation
with respect to such taxes would change by approximately $21.0 million for
each $1.00 change in the "fair market value" of the Class A common stock under
the tax reporting method followed. The average of the high and low trading
prices of the Class A common stock in the when-issued over-the-counter market
on June 4, 1998 was $20.50. In connection with an inter-corporate taxable
transfer of assets entered into in January 1998 by ATC in contemplation of the
separation of ATC and ARS, a portion of the tax with respect to which ATC was
obligated to indemnify CBS has been incurred. Such transfer resulted in an
increase in the tax bases of ATC's assets of approximately $390.0 million. ATC
recorded a deferred tax asset of approximately $150.2 million and will have
potential depreciation and amortization deductions over the next 15 years.
 
  The $212.0 million payment did not include all the taxes payable with
respect to the shares of Class A common stock deliverable upon conversion of
the ARS convertible securities; such taxes will be based on the "fair market
value" of the Class A common stock at the time of conversion. As of
December 31, 1998, ATC estimates that its reimbursement obligation with
respect to taxes on known conversions was approximately $13.5 million, of
which $8.5 million has already been paid. ATC estimates that its remaining
reimbursement obligation with respect to the taxes on convertible securities
that had not then been converted would be approximately $19.1 million under
the tax reporting method followed based on an estimated fair market value of
Class A common stock of $28.75 per share. ATC's obligation for such
conversions would change by approximately $1.1 million for each $1.00 change
in fair market value.
 
  The Separation Agreement also provided for closing balance sheet adjustments
based on the working capital, as defined, and debt levels of ARS as of June 4,
1998. In February 1999, ATC paid CBS $50.0 million in settlement of all
amounts due with respect to such adjustments, including interest. Such
liability was accrued in the Company's December 31, 1998 consolidated
financial statements. ATC also agreed to indemnify CBS and ARS with respect to
certain tax matters affecting ARS prior to the ATC Separation.
 
                                      23
<PAGE>
 
  ATC Preferred Stock Offering: On June 4, 1998, ATC issued $300.0 million of
Interim Preferred Stock and used the proceeds to fund its tax reimbursement
obligation to CBS, to pay the commitment and other fees and expenses of the
issue and sale of such stock and to reduce bank borrowings. As discussed
below, ATC redeemed the Interim Preferred Stock on July 9, 1998. As a result,
American Tower incurred an extraordinary loss of approximately $7.5 million,
net of a tax benefit of $5.0 million, during the third quarter of 1998
representing the write-off of certain commitment, deferred financing and
redemption fees.
 
  July Offering: On July 8, 1998, American Tower completed a public offering
(the "July Offering"') of 27,861,987 shares of Class A common stock, $.01 par
value per share (including 2,361,987 shares sold by American Tower pursuant to
the exercise in full of the underwriters' over-allotment option) at $23.50 per
share. Certain selling stockholders sold an additional 3,874,911 shares in the
offering. American Tower's net proceeds of the offering (after deduction of
the underwriting discount and estimated offering expenses) were approximately
$625.0 million. American Tower used approximately $306.1 million of the net
proceeds from the offering to redeem all of the outstanding shares of the
Interim Preferred Stock at a price of 101% of the stock's liquidation
preference plus accrued and unpaid dividends. ATC invested the balance in
short-term investment grade securities. ATC will continue to use such
investments together with borrowings under the Credit Facilities to fund
acquisitions and construction activities.
 
  February Offering: On February 9, 1999, American Tower completed a public
offering (the "February Offering") of 25,700,000 shares of Class A common
stock, $.01 par value per share (including 1,700,000 shares sold by American
Tower pursuant to the exercise in full of the underwriters' over-allotment
option) at $25.00 per share. Certain selling stockholders sold an additional
1,300,000 shares in the offering. American Tower's net proceeds of the
offering (after deduction of the underwriting discount and estimated offering
expenses) were approximately $619.3 million. American Tower invested the
proceeds in short-term investment grade securities. ATC will continue to use
such investments together with borrowings under its credit facilities to fund
acquisitions and construction activities.
 
  February Private Placement: On February 9, 1999, American Tower consummated
the sale (the "February Private Placement") of 500,000 shares of Class A
common stock to Credit Suisse First Boston Corporation at $26.31 per share,
the closing price of the Class A common stock on the NYSE on February 4, 1999,
the date the stock purchase agreement was executed. In connection with such
sale, Credit Suisse First Boston Corporation was granted certain registration
rights. American Tower invested the proceeds of approximately $13.2 million in
short-term investment grade securities. ATC will continue to use such
investments together with borrowings under the Credit Facilities to fund
acquisitions and construction activities.
 
Year 2000
 
  The Company is aware of the issues associated with the year 2000 as it
relates to information systems and is working to resolve any potential impact
to the Company's operations. The year 2000 issue results from the fact that
many computer programs use only two digits to identify a year in the date
field. These programs were designed and developed without consideration of the
impact of the upcoming change in century. If not corrected, companies could
have computer applications that fail or produce erroneous results at or before
the year 2000.
 
  In December 1998, ATC engaged outside consultants to help it conduct an
extensive review and implement a comprehensive plan to reduce the probability
of operational difficulties due to year 2000 issues. The comprehensive plan
consists of the following phases: (1) awareness phase-- identification of the
problem and designing a structure to support the year 2000 efforts; (2)
definition of critical processes and systems--a process to identify those
activities critical to the Company and focus the efforts of year 2000
activities; (3) assessment phase--inventory the Company's systems, software
and equipment, assessing whether they are year 2000 compliant, prioritizing
those systems, software and equipment not compliant and developing action
plans for remediation and or replacement of non-compliant systems, software
and equipment; (4) renovation phase--converting, replacing or retiring non-
compliant systems, software and equipment; (5) validation phase--testing
converted or replaced systems; (6) implementation phase--place converted or
replaced systems into operations; and (7) contingency planning phase--building
a backup plan to be used in the event that the renovation plan
 
                                      24
<PAGE>
 
cannot be accomplished. This phase will also include planning for year 2000
induced information systems failures on core business processes. The Company's
plan considers both its primary information systems (financial systems
software, network software and equipment, personal computers, etc.) and other
technology and software dependent upon embedded systems (tower equipment,
telephone systems, security systems, etc.)
 
  The Company has completed phases 1 and 2 and is in the process of completing
the assessment phase (phase 3) for both its primary information systems and
its other systems and equipment with embedded software. The assessment phase
is expected to be completed in April 1999. Completion of all phases of the
Company's year 2000 plan is expected in the third quarter of 1999.
 
  The Company did not incur significant costs in 1998 related to developing
and implementing its year 2000 comprehensive plan. The remaining costs
necessary to complete full implementation of the plan, including the
validation and implementation phases, is estimated to be between $0.5 million
and $1.5 million.
 
  Although there can be no assurance that the Company will successfully
complete implementation of its year 2000 comprehensive plan, the project is
currently progressing in accordance with timetables established by the
Company. Although failure to complete implementation on a timely basis may
have material adverse financial and operational impacts on the Company, the
Company believes such failure is not reasonably likely. The possible effects
of unsuccessful implementation of the comprehensive plan include the
following: (i) an inability to process transactions, (ii) a temporary
inability to order supplies or materials, (iii) a temporary inability to
timely process orders and billings, and (iv) a temporary inability to deliver
quality products and services to customers.
 
  The Company's business is dependent upon the systems of various third
parties. With regard to these vendors, the Company is in the process of
assessing their year 2000 readiness based upon communications with each such
vendor. The assessment is expected to be ongoing. The Company believes that a
material financial or business risk could occur if the financial institutions
serving the Company or the Company's utility providers have year 2000 induced
failures.
 
  The Company believes that its most reasonably likely worst case result
relating to year 2000 would be the failure of certain of its systems with
embedded software, or failure of third party systems on which the Company's
systems rely. Failure of systems or equipment with embedded software within
the Company's VVDI segment could result in temporary disruption to that aspect
of the Company's operations. Although there can be no assurance that these
failures would not have an adverse effect on the Company's business, the
Company believes the effect of such failure would not be material to its
business. If the VVDI operations were inoperable for a one week period due to
year 2000 failures, the estimated lost revenue would be approximately $0.4
million.
 
  Within its TRM business segment, computer-controlled devices, such as those
found in automatic monitoring and control systems used for antenna structure
lighting, are vulnerable to year 2000 related malfunctions and may fail, which
would create a hazard to air navigation. Tower owners, such as ATC, are
responsible for tower lighting in compliance with FCC and FAA requirements and
ATC intends to take the necessary steps to address the year 2000 problems,
however, ATC may not be entirely successful.
 
  Currently there are no contingency plans for the potential problems noted
above with the third party vendors, embedded software and lighting systems,
however, ATC has implemented a contingency planning phase as part of its year
2000 plan. The contingency planning phase is estimated to be completed in June
1999.
 
Recent Accounting Pronouncement
 
  In June 1998, the Financial Accounting Standards Board (FASB) issued
Statement of Financial Accounting Standards (FAS) No. 133, "Accounting for
Derivative Instruments and Hedging Activities". This Statement establishes
accounting and reporting standards for derivative instruments. It requires
that an entity recognize all derivatives as either assets or liabilities in
the statement of financial position, and measure those instruments at
 
                                      25
<PAGE>
 
fair value. The accounting for changes in the fair value of a derivative (that
is, gains and losses) will depend on the entity's intended use of the
derivative and its resulting designation (as defined in the Statement). FAS
No. 133 will be effective for all fiscal quarters of all fiscal years
beginning after June 15, 1999. ATC is currently in the process of evaluating
the impact FAS No. 133 will have on the Company and its consolidated financial
statements.
 
ITEM 7A. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK.
 
  The Company is exposed to market risk from changes in interest rates on
long-term debt obligations that impact the fair value of these obligations.
ATC attempts to reduce these risks by utilizing derivative financial
instruments, namely interest rate caps and swaps, pursuant to Company
policies. All derivative financial instruments are for purposes other than
trading.
 
  The following table provides information as of December 31, 1998, about the
Company's market risk exposure associated with changing interest rates. For
long-term debt obligations, the table presents principal cash flows and
related average interest rates by contractual maturity dates. For interest
rate caps and swaps, the table presents notional principal amounts and
weighted-average interest rates by contractual maturity dates.
 
   Principal Payments (In Thousands) and Interest Rate Detail by Contractual
                                Maturity Dates
 
<TABLE>
<CAPTION>
                                      December 31,
                         -------------------------------------------------
                                                                                                     Fair
Long-Term Debt            1999       2000       2001       2002     2003      Thereafter  Total     Value
- --------------           -------    -------    -------    -------  -------    ---------- --------  --------
<S>                      <C>        <C>        <C>        <C>      <C>        <C>        <C>       <C>
Principal Amount(a).....                       $10,500    $17,125  $20,250     $227,125  $275,000  $275,000
Average Interest
 Rate(b)................                            VR%        VR%      VR%          VR%       VR%
 
  Aggregate Notional Principal Amounts Associated with Interest Rate Caps and
    Swaps in Place During the Year and Interest Rate Detail by Contractual
                         Maturity Dates (In thousands)
 
<CAPTION>
Interest Rate CAPS
- ------------------
<S>                      <C>        <C>        <C>        <C>      <C>        <C>        <C>       <C>
Notional Amount......... $73,860(e) $66,860(f)
Weighted-Average Fixed
 Rate(c)................    8.79%      8.82%
<CAPTION>
Interest Rate SWAPs
- -------------------
<S>                      <C>        <C>        <C>        <C>      <C>        <C>        <C>       <C>
Notional Amount......... $24,890    $24,890    $24,890(d) $17,550  $17,550(g)                         $(369)
Weighted-Average Fixed
 Rate(c)................    6.04%      6.04%      6.04%       5.9%     5.9%
</TABLE>
- --------
(a) Long-term debt consists of the Company's Credit Facilities (see the Notes
    to the Consolidated Financial Statements), which provide for total
    available credit of $925.0 million. Interest on the Credit Facilities is
    payable in accordance with the applicable London Interbank Offering Rate
    (LIBOR) agreement or quarterly, and accrues, at the Company's option,
    either at the LIBOR plus margin (as defined) or the Base Rate plus margin
    (as defined). The interest rate in effect at December 31, 1998 for the
    Company's term loan and the Borrower Subsidiaries term loan and revolving
    credit facility was 8.71% and 7.30%, respectively. For the year ended
    December 31, 1998, 1997 and 1996, the weighted average interest rate of
    the Credit Facilities was 7.7%, 7.4% and 8.75%, respectively.
(b) Variable Rate (VR) based on LIBOR or Base Rate plus margin as defined in
    the Credit Facilities Agreement.
(c) Represents the weighted-average-fixed rate of interest based on contract
    notional amount as a percentage of total notional amounts in a given year.
(d) Includes notional amount of $7,340 which will expire in January 2001.
 
                                      26
<PAGE>
 
(e) Includes notional amount of $7,000 which will expire in November 1999.
(f) Includes notional amounts of $21,500, $23,750 and $21,610 which will
    expire in January, April and July, 2000, respectively.
(g) Includes notional amount of $17,550 which will expire in June 2003.
 
  American Tower maintains a portion of its cash and cash equivalents in
short-term financial instruments which are subject to interest rate risks. Due
to the relatively short duration of such instruments and the Company's
expectation that such investments will not be significant on an ongoing basis,
fluctuations in interest rates with respect to such investments should not
materially affect ATC's financial condition or results of operations.
 
ITEM 8. FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA.
 
  See Item 14(a).
 
ITEM 9. CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND
FINANCIAL DISCLOSURE.
 
  Not Applicable.
 
ITEM 10. DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT.
 
  The following table sets forth certain information concerning the executive
officers and directors of ATC:
 
<TABLE>
<CAPTION>
   Name                   Age                           Position
   ----                   ---                           --------
<S>                       <C> <C>
Steven B. Dodge(1)......   53 Chairman of the Board, President and Chief Executive Officer
Alan L. Box.............   47 Executive Vice President and Director
Arnold L.
 Chavkin(1)(2)(3).......   47 Director
James S. Eisenstein.....   40 Executive Vice President--Corporate Development
Dean H. Eisner..........   41 Director
Jack D. Furst...........   40 Director
J. Michael Gearon, Jr...   34 Executive Vice President and Director
Fred R. Lummis..........   45 Director
Randall Mays(2).........   33 Director
Steven J. Moskowitz.....   35 Executive Vice President--Marketing
Thomas H. Stoner(1)(3)..   64 Director
Douglas Wiest...........   46 Chief Operating Officer
Maggie Wilderotter(3)...   44 Director
Joseph L. Winn..........   47 Treasurer and Chief Financial Officer
</TABLE>
- --------
(1) Member of the Executive Committee; Mr. Stoner is the Chairman of the
    Executive Committee.
(2)  Member of the Audit Committee; Mr. Mays is the Chairman of the Audit
     Committee.
(3)  Member of the Compensation Committee; Mr. Stoner is the Chairman of the
     Compensation Committee.
 
  Two independent directors will be elected annually, commencing in 1999, by
the holders of Class A common stock, voting as a separate class. All directors
hold office until the annual meeting of the stockholders of ATC next following
their election or until their successors are elected and qualified. Each
executive officer is appointed annually and serves at the discretion of the
ATC Board of Directors (the "ATC Board").
 
  Steven B. Dodge is the Chairman of the Board, President and Chief Executive
Officer of ATC. Mr. Dodge was also the Chairman of the Board, President and
Chief Executive Officer of American Radio, a position he occupied since its
founding on November 1, 1993 until consummation of the ATC Separation. Mr.
Dodge was the founder in 1988 of Atlantic Radio, L.P. ("Atlantic") which was
one of the predecessor entities of American Radio. Prior to forming Atlantic,
Mr. Dodge served as Chairman and Chief Executive Officer of American
Cablesystems Corporation ("American Cablesystems"), a cable television company
he founded in 1978 and
 
                                      27
<PAGE>
 
operated as a privately-held company until 1986 when it completed a public
offering in which its stock was priced at $14.50 per share. American
Cablesystems was merged into Continental Cablevision, Inc. in 1988 in a
transaction valued at more than $750.0 million, or $46.50 per share. The
initial public offering of American Radio Class A common stock occurred in
June 1995 at a price of $16.50 per share. Upon consummation of the ATC
Separation, each share of American Radio Class A common stock was exchanged
into $44.00 and one share of Class A common stock. Mr. Dodge also serves as a
director of PageMart Wireless, Inc.
 
  Alan L. Box is an Executive Vice President and a director of ATC. Mr. Box
served as Chief Operating Officer of ATC from June 1997 to March 1998, at
which time he assumed his present role as the Executive Vice President
responsible for the video, voice, data and Internet transmission business of
ATC. Mr. Box also was an Executive Vice President and a director of American
Radio from April 1997, when EZ Communications, Inc. ("EZ") merged into
American Radio (the "EZ Merger"), until consummation of the ATC Separation.
Prior to the EZ Merger, Mr. Box was employed by EZ, starting in 1974, as the
General Manager of EZ's Washington, D.C. area radio station. He became
Executive Vice President and General Manager and a director of EZ in 1979,
President of EZ in 1985 and Chief Executive Officer of EZ in 1995. He serves
as a director of George Mason Bankshares, Inc. and George Mason Bank.
 
  Arnold L. Chavkin is a member of the Executive Committee, the Audit
Committee and the Compensation Committee of the ATC Board. Mr. Chavkin was the
Chairman of the Audit Committee of the Board of American Radio from its
founding until consummation of the ATC Separation and of the Audit Committee
of ATC from November 1997 until November 1998. Mr. Chavkin is a general
partner of Chase Capital Partners ("CCP"), which is a general partner of Chase
Equity Associates, L.P. ("CEA"), a stockholder of ATC, and a former principal
stockholder of American Radio and of Multi Market Communications, Inc., one of
the predecessors of American Radio. Mr. Chavkin has been a General Partner of
CCP and CVP since January 1992 and has served as the President of Chemical
Investments, Inc. since March 1991. Chase Manhattan Capital, L.P. ("Chase
Capital"), which is an affiliate of CEA, owned approximately 18.1% of Old ATC;
The Chase Manhattan Bank ("Chase"), which is also an affiliate of Chase
Capital, is a lender under the Credit Facilities for the Borrower Subsidiaries
with a 5.2% participation. Mr. Chavkin is also a director of R&B Falcon
Drilling Corporation, Wireless One, Inc. and Patina Oil & Gas Corporation.
Prior to joining Chemical Investments, Inc., Mr. Chavkin was a specialist in
investment and merchant banking at Chemical Bank for six years.
 
  James S. Eisenstein is the Executive Vice President--Corporate Development
of ATC. Mr. Eisenstein has overall responsibility for seeking out acquisition
and development opportunities for ATC. Mr. Eisenstein helped form ATC in the
summer of 1995. From 1990 to 1995, he was Chief Operating Officer for Amaturo
Group Ltd., a broadcast company operating 11 radio stations and four
broadcasting towers, several of which were purchased by American Radio. Mr.
Eisenstein serves on the Board of Directors of the Personal Communications
Industry Association, the leading international trade association representing
the wireless communications industry. He has extensive experience in
structuring acquisitions and the operation and management of broadcasting and
tower businesses.
 
  Dean H. Eisner, a director of ATC, has since May 1995 served as Vice
President, Business Development and Planning of Cox Enterprises, Inc., an
affiliate of Cox Telecom Towers, Inc., the former principal member of TeleCom
Towers, L.L.C. ("TeleCom"). Prior to that he served as Treasurer of Cox
Enterprises, Inc. starting in January 1993, and Managing Director,
International Development, starting in February 1992.
 
  Jack D. Furst, a director of ATC, was Chairman of OmniAmerica Inc. and,
since 1989, has been a Partner of Hicks, Muse, Tate & Furst, Incorporated, an
affiliate of OmniAmerica Inc.'s former principal stockholder ("Hicks, Muse").
Mr. Furst currently serves as a Director of Cooperative Computing, Inc.,
Hedstrom Corp., International Wire Holding Company, Viasystems, Inc., Home
Interiors & Gifts, Inc. and Triton Energy Limited.
 
  J. Michael Gearon, Jr. was the principal stockholder and Chief Executive
Officer of Gearon, a position he has held since September 1991. As a condition
to consummation of the Gearon Transaction, Mr. Gearon was elected a director
of ATC and President of Gearon Communications, the division of ATC which
operates its site acquisition business.
 
                                      28
<PAGE>
 
  Fred R. Lummis, a member of the Audit Committee of the ATC Board, has served
as Chairman, President and Chief Executive Officer of Advantage Outdoor
Company, L.P. since the consummation of the merger with American Tower
Corporation, an unaffiliated company that was merged with ATC in June 1998
("Old ATC") and served as Chairman, Chief Executive Officer and President of
Old ATC from the time of its organization in October 1994 until June 1998. Mr.
Lummis has been the President of Summit Capital, a private investment firm,
since June 1990. Mr. Lummis currently serves on the board of several private
companies and is a trustee of the Baylor College of Medicine.
 
  Randall Mays, Chairman of the Audit Committee of the ATC Board, has served
as Chief Financial Officer and Executive Vice President of Clear Channel since
February 1997, prior to which he had served as a Vice President and Treasurer
since joining Clear Channel in 1993. Prior to joining Clear Channel, he was an
associate at Goldman, Sachs & Co. Clear Channel was a principal stockholder of
Old ATC with a 31.3% interest.
 
  Steven J. Moskowitz is the Executive Vice President--Marketing and General
Manager of the Northeast Region of ATC. Mr. Moskowitz joined ATC in January
1998, initially as a Vice President and General Manager of the Northeast
Region, and assumed his current position in March 1999. From 1989 until
December 1997, Mr. Moskowitz served as a Vice President of The Katz Media
Group, the largest broadcast media representation firm in the U.S.
 
  Thomas H. Stoner is the Chairman of the Executive Committee and the
Compensation Committee of the ATC Board. Mr. Stoner was the Chairman of the
Executive Committee and the Compensation Committee of the Board of American
Radio since its founding until consummation of the ATC Separation. Mr. Stoner
founded Stoner Broadcasting Systems, Inc. ("Stoner") in 1965. Stoner, which
was one of the predecessors of American Radio, operated radio stations for
over 25 years in large, medium and small markets. Mr. Stoner is a director of
Gaylord Container Corporation and a trustee of the Chesapeake Bay Foundation.
 
  Douglas Wiest is the Chief Operating Officer of ATC. Mr. Wiest joined ATC in
February 1998, initially as the Chief Operating Officer of Gearon
Communications, and assumed his current position in March 1998. Prior to
joining ATC, Mr. Wiest was Regional Vice President of Engineering and
Operations for Nextel's southern region. Prior to joining Nextel in 1993, Mr.
Wiest was employed by McCaw Communications where he was engaged in network
systems development for approximately three years and by Pacific Telesis where
he was engaged in strategic planning and operations for approximately eight
years.
 
  Maggie Wilderotter is a member of the Compensation Committee of the ATC
Board. Ms. Wilderotter is the President and Chief Executive Officer of Wink
Communications ("Wink"), a California company that develops technology for
adding simple interactivity and graphics to mass-market consumer electronic
products. Before joining Wink, Ms. Wilderotter was the Executive Vice
President of National Operations for AT&T Wireless Services, Inc., and Chief
Executive Officer of AT&T's Aviation Communications Division. Ms. Wilderotter
has also served as Senior Vice President of McCaw Cellular Communications,
Inc. and Regional President of its California, Arizona, New Mexico, Nevada and
Hawaii Region. Prior to her work in the wireless industry, Ms. Wilderotter
spent 12 years with U.S. Computer Services, Inc./Cable Data, as Senior Vice
President and General Manager. In 1989 she was the recipient of the National
Cable Television Association's Vanguard Award and the Top Women in Cable &
Telecommunications award. Ms. Wilderotter serves on the boards of Airborne
Express, Electric Lightwave, Inc., Gaylord Entertainment, Jacor Communications
and the California Cable Television Association.
 
  Joseph L. Winn is the Chief Financial Officer and Treasurer of ATC. Mr. Winn
was also Treasurer, Chief Financial Officer and a director of American Radio
since its founding until consummation of the ATC Separation. In addition to
serving as Chief Financial Officer of American Radio, Mr. Winn was Co-Chief
Operating Officer responsible for Boston operations until May 1994. Mr. Winn
served as Chief Financial Officer and a director of the general partner of
Atlantic after its organization. He also served as Executive Vice President of
the general partner of Atlantic from its organization until June 1992, and as
its President from June 1992 until the organization of American Radio. Prior
to joining Atlantic, Mr. Winn served as Senior Vice President and Corporate
Controller of American Cablesystems after joining that company in 1983.
 
                                      29
<PAGE>
 
ITEM 11. EXECUTIVE COMPENSATION.
 
  All of the executive officers of ATC listed below (other than Messrs.
Eisenstein, Gearon and Wiest) were employees of American Radio (or, in the
case of Mr. Box, of EZ prior to the EZ Merger) since the organization of ATC
in 1995 until the ATC Separation. During that period the highest paid
executive officers, other than Mr. Dodge, who are employees of ATC, were
Messrs. Box, Eisenstein, Gearon, Wiest and Winn. The compensation of each of
those individuals (other than Messrs. Eisenstein, Gearon and Wiest) was
principally for acting as an executive officer of American Radio (or, in the
case of Mr. Box, EZ prior to the EZ Merger) and, accordingly, information
provided with respect to their executive compensation represents compensation
paid by American Radio (with the exception of Messrs. Eisenstein, Gearon and
Wiest).
 
                          Summary Compensation Table
 
<TABLE>
<CAPTION>
                                                                         Long-Term
                                 Annual Compensation                    Compensation
                          --------------------------------------------- ------------
                                                                           Shares
   Name and Principal                                      Other Annual  Underlying       All Other
        Position          Year  Salary              Bonus  Compensation  Options(7)      Compensation
   ------------------     ---- --------            ------- ------------ ------------     ------------
<S>                       <C>  <C>                 <C>     <C>          <C>              <C>
Steven B. Dodge(1)(2)...  1996 $297,250(/3/)       $50,000      --          40,000         $ 4,910(/9/)
 Chairman of the Board,   1997 $502,338(/3/)            --      --         100,000         $ 1,716(/9/)
 President and Chief
 Executive                1998 $370,349(/5/)            --      --       3,300,000         $ 5,946(/9/)
 Officer
 
Douglas Wiest(2)........  1998 $211,007(/5/)            --      --         365,001         $ 4,576(/10/)
 Chief Operating Officer
 
J. Michael Gearon,
 Jr.(2).................  1998 $176,135(/5/)            --      --         334,451         $   346(/11/)
 Executive Vice
 President
 
Joseph L. Winn(1)(2)....  1996 $257,250(/3/)        42,500      --          20,000         $11,456(/9/)
 Treasurer and Chief
 Financial                1997 $352,329(/3/)        40,000      --          35,000         $12,876(/9/)
 Officer                  1998 $298,779(/4/)            --      --         610,000         $13,210(/9/)
 
James S. Eisenstein(2)..  1996 $169,250(/5/)        19,000      --         273,119(/8/)    $ 8,669(/9/)
 Executive Vice
 President--              1997 $212,367(/5/)            --      --         27,3100(/8/)    $12,656(/9/)
 Corporate Development    1998 $204,850(/5/)(/13/)  50,000      --         150,000         $13,295(/9/)
 
Alan L. Box(1)(2).......  1997 $264,400(/6/)            --      --         100,000         $ 1,216(/12/)
 Executive Vice
 President                1998 $105,417(/5/)            --      --         225,000         $   174(/11/)
</TABLE>
- --------
 (1) Represents both annual and long-term compensation paid by American Radio
     and American Tower.
 (2)  The Compensation Committee of ATC approved annual base salaries for 1998
      for Mr. Dodge, and each of its other five executive officers, at the
      following rates: Mr. Dodge: $250,000; Mr. Box: $50,000; Mr. Eisenstein
      $200,000; Mr. Gearon: $200,000; Mr. Wiest: $225,000; and Mr. Winn:
      $225,000. Such salaries commenced (in the case of Messrs. Dodge, Winn
      and Eisenstein) with the consummation of the ATC Separation on June 4,
      1998, prior to which time such individuals (other than Mr. Eisenstein)
      were paid by American Radio at their then present compensation rates.
 (3)  Includes American Radio's matching 401(k) plan contributions.
 (4)  Includes American Radio and American Tower matching 401(k) plan
      contributions.
 (5)  Includes American Tower matching 401(k) plan contributions.
 (6)  Includes $87,500 paid by ATC commencing October 1, 1997.
 (7)  Except in the case of Mr. Eisenstein, represents for the years 1996 and
      1997 options to purchase American Radio common stock granted by American
      Radio; such options, to the extent they were unexercised at the time of
      the ATC Separation, were exchanged for options to purchase shares of
      common stock on the basis and for the numbers shown under "--Stock
      Option Information" below. In the case of Mr. Eisenstein, does not
      include options granted in 1996 to purchase 40,000 shares of ARS common
      stock by American Radio that were similarly exchanged.
 
                                      30
<PAGE>
 
 (8)  Represents options issued in exchange for options to purchase shares of
      ATI granted pursuant to the ATI plan that were exchanged as part of the
      ATC Separation for options to purchase shares of Class A common stock.
      See Note (7) above for information with respect to options to purchase
      ARS common stock that are not reflected in Mr. Eisenstein's 1996
      numbers.
 (9)  Includes group term life insurance, automobile lease and parking
      expenses paid by American Radio and American Tower.
(10) Includes group term insurance and automobile expense paid by American
     Tower.
(11)  Includes group term life insurance paid by American Tower.
(12)  Includes group term life insurance paid by American Radio.
(13)  Mr. Eisenstein also received a $1,022,366 demand loan in August 1998. In
      December 1998, Mr. Eisenstein repaid $700,000, and as of December 31,
      1998, such loan bore interest at a fixed rate and remained outstanding
      in the principal amount of $322,366.
 
Director Compensation
 
  The independent directors of ATC have received options to purchase 50,000
shares of Class A common stock, which are exercisable in 20% cumulative annual
increments commencing one year from the date of grant and expire at the end of
ten years. The outside directors also receive $2,500 for attending each board
meeting, $1,000 for each committee on which he or she serves, and $3,000 for
each committee on which he or she serves as chairperson.
 
Stock Option Information
 
  Effective November 5, 1997, ATC instituted the 1997 Stock Option Plan, as
amended and restated (the "Plan"), which is administered by the Compensation
Committee of the ATC Board. The Plan was designed to encourage directors,
consultants and key employees of American Tower and its subsidiaries to
continue their association with ATC by providing opportunities for such
persons to participate in the ownership of ATC and in its future growth
through the granting of stock options, which may be options designed to
qualify as incentive stock options ("ISOs") within the meaning of Section 422
of the Internal Revenue Code of 1986, as amended (the "Code"), or options not
intended to qualify for any special tax treatment under the Code ("NQOs"). The
Plan provides that ATC may not grant options to purchase more than 5,000,000
shares per year per participant.
 
  The duration of the ISOs and NQOs granted under the Plan may be specified by
the Compensation Committee pursuant to each respective option agreement, but
in no event shall any such option be exercisable after the expiration of ten
(10) years after the date of grant. In the case of any employee who owns (or
is considered under Section 424(d) of the Code as owning) stock possessing
more than ten percent of the total combined voting power of all classes of
stock of ATC, no ISO shall be exercisable after the expiration of five (5)
years from the date such option is granted. The option pool under the Plan
consists of an aggregate of 15,000,000 shares of common stock that may consist
of shares of Class A common stock, shares of Class B common stock or some
combination thereof. The Plan was amended in June 1998 to provide that all
future grants of options under the Plan must be to purchase shares of Class A
common stock. The Plan includes options that were converted from the stock
option plan of ATI. In July 1996, ATI adopted a stock option plan and,
pursuant thereto, options were granted to various officers of ATI. In
connection with the ATC Separation, those options to purchase the common stock
of ATI were converted into options to acquire shares of Class A common stock
under the Plan.
 
  In addition to the 15,000,000 shares authorized under the Plan, options to
purchase an aggregate of 2,168,466 shares of common stock were outstanding as
of December 31, 1998 outside of the Plan. These options are the result of the
exchange of certain American Radio options that occurred pursuant to the ATC
Separation and the assumption of certain options that occurred pursuant to the
merger with Old ATC. Each unexercised option to purchase shares of American
Radio common stock held by persons who became directors or employees of ATC
were exchanged for ATC options. The American Radio options were exchanged in a
manner that
 
                                      31
<PAGE>
 
preserved the spread in such American Radio options between the option
exercise price and the fair market value of American Radio common stock and
the ratio of the spread to the exercise price prior to such conversion and, to
the extent applicable, otherwise in conformity with the rules under Section
424(a) of the Code and the regulations promulgated thereunder.
 
  During the year ended December 31, 1998 the only options granted pursuant to
the Plan to the individuals referred to in "--Executive Compensation" above
were as shown below. All such options (other than that for 1,700,000 shares of
Class B common stock granted to Mr. Dodge) are to purchase shares of Class A
common stock.
 
                             Option Grants in 1998
                               Individual Grants
 
<TABLE>
<CAPTION>
                                     Percent of
                                       Total                         Potential Realizable
                          Number of   Options                        Value at Annual Rates
                          Shares of  Granted to Exercise              of Appreciation for
                          Underlying Employees   Price                 Option Terms (b)
                           Options   in Fiscal    per    Expiration -----------------------
          Name             Granted    Year(a)    Share      Date        5%          10%
          ----            ---------- ---------- -------- ---------- ----------- -----------
<S>                       <C>        <C>        <C>      <C>        <C>         <C>
Steven B. Dodge.........  1,700,000     20.3    $ 10.00     1/7/08  $10,691,209 $27,093,622
                          1,300,000     15.5     21.125    6/21/08   17,275,107  43,778,512
                            300,000      3.6      23.75   12/01/08    4,480,874  11,355,415
Douglas Wiest...........    240,001      2.9      13.00    1/21/08    1,962,159   4,972,497
                            125,000      1.5      23.75   12/01/08    1,867,031   4,731,423
J. Michael Gearon, Jr...    234,451      2.8      13.00    1/21/08    1,916,785   4,857,509
                            100,000      1.2      23.75   12/01/08    1,493,625   3,785,138
Joseph L. Winn..........    275,000      3.3      10.00     1/7/08    1,729,460   4,382,792
                            210,000      2.5     21.125    6/21/08    2,790,594   7,071,913
                            125,000      1.5      23.75   12/01/08    1,867,031   4,731,423
Alan L. Box.............    120,000      1.4      10.00     1/7/08      754,674   1,912,490
                             80,000      1.0     21.125    6/21/08    1,063,083   2,694,062
                             25,000      0.3      23.75   12/01/08      373,406     946,285
James S. Eisenstein.....     28,000      0.3      10.00     1/7/08      176,090     446,248
                             22,000      0.3     21.125    6/21/08      292,348     740,867
                            100,000      1.2      23.75   12/01/08    1,493,625   3,785,138
</TABLE>
- --------
(a) The total number of options granted to employees of ATC during 1998
    pursuant to the Plan was 8,371,700.
(b)  The potential realizable value at assumed annual rates of stock price
     appreciation for the option term of 5% and 10% would be $16.29 and $25.94
     respectively, with respect to the $10.00 per share options, $34.42 and
     $54.81, respectively, with respect to the $21.125 per share options and
     $21.18 and $33.72 respectively, with respect to the $13.00 per share
     options and $38.69 and $61.60, respectively, with respect to the $23.75
     per share option. A 5% and 10% per year appreciation in stock price from
     $10.00 per share yields appreciation of $6.29 per share and $15.94 per
     share, respectively. A 5% and 10% per year appreciation in stock price
     from $21.125 per share yields appreciation of $13.29 per share and $33.68
     per share, respectively. A 5% and 10% per year appreciation in stock
     price from $13.00 per share yields appreciation of $8.18 per share and
     $20.72 per share, respectively. A 5% and 10% per year appreciation in
     stock price from $23.75 per share yields appreciation of $14.94 per share
     and $37.85 per share, respectively. The actual value realized, if any,
     will depend on the excess of the stock price over the exercise price on
     the date the option is exercised, so that there is no assurance the value
     realized by an executive will be at or near the amounts reflected in this
     table.
 
                                      32
<PAGE>
 
  The unexercised options granted pursuant to the Plan (or outstanding with
respect to options granted under the American Radio plan or the ATI plan) to
the individuals referred to in "--Executive Compensation" were as follows:
 
<TABLE>
<CAPTION>
                                    Number of           Value of Unexercised
                             Unexercised Options at    In-the-Money Options at
                                December 31, 1998        December 31, 1998(a)
                            ------------------------- -------------------------
           Name             Exercisable Unexercisable Exercisable Unexercisable
           ----             ----------- ------------- ----------- -------------
<S>                         <C>         <C>           <C>         <C>
Steven B. Dodge............   484,816     3,716,441   $12,248,812  $55,097,654
Douglas Wiest..............         0       365,001             0    4,700,667
J. Michael Gearon, Jr......         0       334,451             0    4,463,509
Joseph L. Winn.............    95,883       740,526     2,371,611   10,613,051
Alan L. Box................    62,156       473,622     1,292,223    8,335,701
James S. Eisenstein........   243,922       330,819     6,010,720    5,759,475
</TABLE>
- --------
(a) Based on the closing price of the Class A common stock on the NYSE on
    December 31, 1998 of $29.56 per share.
 
  All employees of American Radio who became employees of ATC (which includes,
among others, Messrs. Box, Dodge, Eisenstein and Winn) who held options to
purchase American Radio common stock (including Mr. Box: 100,000 shares; Mr.
Dodge: 290,000 shares; Mr. Eisenstein: 40,000 shares; and Mr. Winn: 280,000
shares) were given the opportunity to convert their American Radio options
into ATC options. Such conversion was effectuated upon consummation of the ATC
Separation in a manner designed to preserve the spread in such American Radio
options between the option exercise price and the fair market value of
American Radio common stock and the ratio of the spread to the exercise price
prior to such conversion and, to the extent applicable, otherwise in
conformity with the rules under Section 424(a) of the Code and the regulations
promulgated thereunder. Messrs. Box, Dodge, Eisenstein and Winn exercised
their respective rights to exchange American Radio options for ATC options
such that such individuals hold ATC options as follows (based on a $64 7/8 and
$20 7/8 per share value for the American Radio common stock and ATC common
stock, respectively): Mr. Box: 310,778 shares of Class A common stock at $8.77
per share; Mr. Dodge: an aggregate of 901,257 shares of Class B common stock
at prices ranging between $3.19 and $10.00 per share; Mr. Eisenstein: 124,311
shares of Class B common stock at $7.64 per share; and Mr. Winn: an aggregate
of 405,037 shares of Class B common stock and 25,080 shares of Class A common
stock at prices ranging between $2.05 and $9.09 per share. See "Item 12.
Security Ownership of Certain Beneficial Owners and Management" below.
 
  In 1996 Mr. Eisenstein was granted options pursuant to the ATI plan for an
aggregate of 200,000 shares at $5.00 per share. Such options became
exercisable to the extent of 80,000 shares on July 1, 1997 and became
exercisable in 20% cumulative annual increments commencing on July 1, 1998,
and expires September 9, 2006. As part of the ATC Separation, the ATI options
were exchanged for ATC options, and Mr. Eisenstein received options to
purchase 273,117 shares of Class A common stock at $3.66 per share, of which
163,871 shares are presently purchasable. An additional ten-year option to
purchase 20,000 shares of common stock of ATI at $7.50 per share was granted
to Mr. Eisenstein on January 2, 1997. Pursuant to the ATC Separation, that
option was exchanged for an ATC option to purchase 27,311 of shares of Class A
common stock at $5.49 per share, of which 5,462 shares are presently
purchasable.
 
Employment Agreements
 
  J. Michael Gearon, Jr. and Douglas Wiest are the only executive officers
that have employment agreements with ATC. Mr. Gearon entered into his
employment agreement in connection with the closing of the Gearon Transaction.
Such employment agreement is for an initial term ending December 31, 2000 and
is thereafter renewable for successive one year periods. It provides that Mr.
Gearon shall receive an annual base salary of $200,000 and shall be eligible
to participate in ATC's stock option plan and other benefits. Mr. Wiest's
employment agreement provides for a lump sum cash payment of $350,000, or 1.5
times Mr. Wiest's salary, if Mr. Wiest's employment is terminated (except for
cause) within five years of the date of the employment
 
                                      33
<PAGE>
 
agreement (April 13, 1998). It also provides that under certain circumstance
if ATC is sold within such five year period then Mr. Wiest would be entitled
to the accelerated vesting of any options he held at such time.
 
Compensation Committee Interlocks and Insider Participation
 
  Mr. Stoner (and certain members of his family) and an affiliate of Mr.
Chavkin purchased Class A common stock in the ATC Private Placement. Also
Chase, an entity related to CEA, an affiliate of Mr. Chavkin, has been a
lender to ATC and is a lender under the Credit Facilities. Each of these
matters is explained below under "Item 13. Certain Relationships and Related
Transactions" below.
 
ITEM 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT
 
  The following information sets forth certain information known to ATC as of
March 15, 1999 with respect to the shares of common stock that are
beneficially owned as of such date by (i) each person known by ATC to own more
than 5% of the outstanding common stock (ii) each director of ATC, (iii) each
executive officer of ATC, and (iv) all directors and executive officers of ATC
as a group. The number of shares beneficially owned by each director or
executive officer is determined according to the rules of the Securities and
Exchange Commission, and the information is not necessarily indicative of
beneficial ownership for any other purpose. Under such rules, beneficial
ownership includes any shares as to which the individual or entity has sole or
shared voting power or investment power and also any shares which the
individual or entity has the right to acquire within sixty days of March 15,
1999 through the exercise of an option, conversion feature or similar right.
Except as noted below, each holder has sole voting and investment power with
respect to all shares of Common Stock listed as owned by such person or
entity.
 
<TABLE>
<CAPTION>
                                                                         Percent
                                                                           of
                                                              Percent of  Total
                                        Percent of Percent of   Common   Voting
                               Number    Class A    Class B     Stock     Power
                             ---------- ---------- ---------- ---------- -------
<S>                          <C>        <C>        <C>        <C>        <C>
Directors and Executive
 Officers
Steven B. Dodge(1).........   6,614,460     *        66.03       4.18     26.67
Thomas H. Stoner(2)........   1,493,300     *        16.32        *        6.22
Alan L. Box(3).............     849,240     *          --         *         *
Arnold L. Chavkin
 (CEA)(4)..................   6,285,708    2.65        --        4.00      1.64
James S. Eisenstein(5).....     279,984     *          --         *         *
Dean H. Eisner(6)..........   1,881,055    1.29        --        1.20       *
Jack D. Furst(7)...........      19,364     *          --         *         *
J. Michael Gearon, Jr.(8)..   4,021,328    2.76        --        2.56      1.71
Fred R. Lummis(9)..........   1,346,748     *          --         *         *
Randall Mays (Clear
 Channel)(10)..............   9,019,717    6.19        --        5.74      3.83
Steven J. Moskowitz(11)....      56,000     *          --         *         *
Douglas Wiest(12)..........      83,557     *          --         *         *
Maggie Wilderotter(13).....         --      --         --         --        --
Joseph L. Winn(14).........     417,826     *         3.87        *        1.51
All executive officers and
 directors as a group
 (fourteen persons)(15)....  32,368,287   14.68      83.51      20.31     42.64
Five Percent Stockholders:
Wellington Management
 Company, LLP(16)..........   8,091,887    5.55        --        5.15      3.44
</TABLE>
- --------
 *  Less than 1%.
 (1) Mr. Dodge is Chairman of the Board, President and Chief Executive Officer
     of ATC. His address is 116 Huntington Avenue, Boston, Massachusetts
     02116. Includes 10,030 shares of Class A common stock and 3,567,761
     shares of Class B common stock owned by Mr. Dodge, an aggregate of 25,050
     shares of Class A Common Stock and 28,065 shares of Class B common stock
     owned by three trusts for the benefit of
 
                                      34
<PAGE>
 
    Mr. Dodge's children, 66,720 shares of Class A common stock and 2,000,000
    shares of Class B common stock owned by a limited liability company, of
    which Mr. Dodge is the sole member and 5,000 shares of Class A common
    stock owned by Mr. Dodge's wife. Mr. Dodge disclaims beneficial ownership
    in all shares owned by such trusts and his wife. Does not include an
    aggregate of 329,423 shares of Class B common stock purchasable under ATC
    options received in exchange for American Radio options upon consummation
    of the ATC Separation; includes an aggregate of 571,834 shares of Class B
    common stock as to which such exchanged options are exercisable. Does not
    include 1,360,000 shares of Class B common stock purchasable under an
    option granted on January 8, 1998 under the Plan and 1,300,000 shares of
    Class A common stock purchasable under an option granted on June 22, 1998
    under the Plan and 300,000 shares of Class A common stock purchasable
    under an option granted on December 1, 1998 under the Plan; includes
    340,000 shares as to which the January option is exercisable. Does not
    include 170 shares of Class A common stock held by Thomas S. Dodge, an
    adult child of Mr. Dodge, with respect to which Mr. Dodge disclaims
    beneficial ownership.
 (2) Mr. Stoner is Chairman of the Executive Committee of the ATC Board of
     Directors. His address is 116 Huntington Avenue, Boston, Massachusetts
     02116. Includes 46,311 shares of Class B common stock owned by his wife,
     an aggregate of 1,316,285 shares of Class B common stock and 22,500
     shares of Class A common stock owned by trusts of which he and/or certain
     other persons are trustees, and 96,988 shares of Class B common stock
     owned by a charitable foundation, of which Mr. Stoner serves as an
     officer. Mr. Stoner disclaims beneficial ownership of 318,853 shares of
     Class B common stock and 22,500 shares of Class A common stock owned by
     the charitable foundation and such trusts. Does not include 100,675
     shares of Class A common stock and 63,629 shares of Class B common stock
     owned by Mr. Stoner's adult children. Does not include 9,323 shares of
     Class A common stock purchasable under an ATC option received in exchange
     for an American Radio option upon consummation of the ATC Separation;
     includes 6,216 shares of Class A common stock as to which such exchanged
     option is exercisable. Does not include 20,000 shares of Class A common
     stock purchasable under an option granted on January 8, 1998 under the
     Plan and 25,000 shares of Class A common stock purchasable under an
     option granted on December 1, 1998 under the Plan; includes 5,000 shares
     as to which the January option is exercisable.
 (3) Mr. Box is a director and an Executive Vice President of ATC. His address
     is 116 Huntington Avenue, Boston, Massachusetts 02116. Includes 848,858
     shares of Class A common stock owned by Mr. Box, 2,070 shares of Class A
     common stock owned by two trusts for the benefit of Mr. Box's children
     and 124,312 shares of Class A common stock purchasable under ATC options
     received in exchange for American Radio options upon consummation of the
     ATC Separation; does not include 186,466 shares of Class A common stock
     purchasable under such exchanged options. Does not include 96,000 shares
     of Class A common stock purchasable under an option granted on January 8,
     1998 under the Plan, 80,000 shares of Class A common stock purchasable
     under an option granted on June 22, 1998 under the Plan and 25,000 shares
     of Class A common stock purchasable under an option granted on December
     1, 1998 under the Plan; includes 24,000 shares as to which the January
     option is exercisable.
 (4) Mr. Chavkin is a director of ATC. His address is 116 Huntington Avenue,
     Boston, Massachusetts 02116. Mr. Chavkin, as a general partner of CCP,
     which is the general partner of CEA may be deemed to own beneficially
     shares held by CEA and Chase Capital, an affiliate of Mr. Chavkin.
     Includes 21,719 shares of Class A common stock and 2,422,804 shares of
     Class C common stock owned by CEA and 3,829,969 shares of Class A common
     stock owned by Chase Capital. Mr. Chavkin disclaims such beneficial
     ownership of such shares. The address of CCP and CEA is 380 Madison
     Avenue, 12th Floor, New York, New York 10017. Does not include 9,323
     shares of Class A common stock purchasable under an ATC option received
     in exchange for an American Radio option upon consummation of the ATC
     Separation; includes 6,216 shares of Class A common stock as to which
     such exchanged option is exercisable. Does not include 20,000 shares of
     Class A common stock purchasable under an option granted on January 8,
     1998 under the Plan and 25,000 shares of Class A common stock purchasable
     under an option granted on December 1, 1998 under the Plan; includes
     5,000 shares as to which the January option is exercisable.
 (5) Mr. Eisenstein is Executive Vice President--Corporate Development of ATC.
     His address is 116 Huntington Avenue, Boston, Massachusetts 02116. Does
     not include 49,722 shares of Class B common
 
                                      35
<PAGE>
 
    stock purchasable under ATC options received in exchange for American
    Radio options upon consummation of the ATC Separation; includes 74,589
    shares of Class B common stock as to which such options will be
    exercisable. Does not include an aggregate of 125,635 shares of Class A
    common stock purchasable under options that were issued in exchange for
    ATI options; includes an aggregate of 174,795 shares of Class A common
    stock as to which such options are exercisable. Does not include 22,400
    shares of Class A common stock purchasable under an option granted on
    January 8, 1998 under the Plan, 22,000 shares of Class A common stock
    purchasable under an option granted on June 22, 1998 under the Plan and
    100,000 shares of Class A common stock purchasable under an option granted
    on December 1, 1998 under the Plan; includes 5,600 shares as to which the
    January option is exercisable.
 (6) Mr. Eisner, Vice President, Business Development and Planning of Cox
     Enterprises, Inc., an affiliate of the former principal TeleCom member,
     is a director of ATC. Cox Telecom Towers, Inc., an affiliate of Cox
     Enterprises, Inc., owns 1,881,055 shares of Class A common stock. Mr.
     Eisner's address is 1400 Lake Hearn Drive, N.E., Atlanta, GA 30319.
 (7)  Mr. Furst, a partner of Hicks, Muse, is a director of ATC. His address
      is 200 Crescent Court, Suite 1600, Dallas, Texas 75201-6950.
 (8) Mr. Gearon is an Executive Vice President and director of ATC. His
     address is 116 Huntington Avenue, Boston, Massachusetts 02116. Includes
     3,974,437 shares of Class A common stock currently owned by Mr. Gearon.
     Does not include 300,000 shares of Class A common stock held by a trust
     for the benefit of Mr. Gearon's children of which J. Michael Gearon, Sr.
     is the trustee. Mr. Gearon disclaims beneficial ownership in all shares
     owned by such trust. Does not include 187,560 shares of Class A common
     stock purchasable under an option granted on January 22, 1998 under the
     Plan and 100,000 shares of Class A common stock purchasable under an
     option granted on December 1, 1998 under the Plan; includes 46,891 shares
     as to which the January option is exercisable.
 (9) Mr. Lummis is a director of ATC. His address is 3411 Richmond Avenue,
     Suite 400, Houston, Texas 77046. Includes 69,105 shares of Class A common
     stock owned by Mr. Lummis, an aggregate of 256,252 shares of Class A
     common stock owned by trusts of which he is trustee, 674,349 shares of
     Class A common stock owned by Summit Capital, an affiliate of Mr. Lummis
     by reason of Mr. Lummis's 50% ownership of the common stock of Summit
     Capital, and 497,042 shares of Class A common stock purchasable under an
     option originally granted by Old ATC which became an option to purchase
     Class A common stock pursuant to the merger of Old ATC with ATC. Mr.
     Lummis disclaims beneficial ownership in all shares owned by the trusts
     and disclaims beneficial ownership of all shares owned by Summit Capital,
     except to the extent of his pecuniary interest therein. Does not include
     25,000 shares of Class A common stock purchasable under an option granted
     on June 22, 1998 under the Plan and 25,000 shares of Class A common stock
     purchasable under an option granted on December 1, 1998 under the Plan.
(10)  Mr. Mays, the Chief Financial Officer and an Executive Vice President of
      Clear Channel, is a director of ATC. His address is P.O. Box 659512, San
      Antonio, Texas 78265-9512. Clear Channel owns all of the shares of Class
      A common stock shown in the table. Mr. Mays disclaims beneficial
      ownership of Clear Channel's ownership of such shares. Does not include
      25,000 shares of Class A common stock purchasable under an option
      granted on June 22, 1998 under the Plan and 25,000 shares of Class A
      common stock purchasable under an option granted on December 1, 1998
      under the Plan.
(11) Mr. Moskowitz is Executive Vice President--Marketing of ATC. His address
     is 116 Huntington Avenue, Boston, Massachusetts 02116. Does not include
     112,000 shares of Class A Common Stock purchasable under an option
     granted on January 8, 1998 under the Plan and 35,000 shares purchasable
     under an option granted on June 22, 1998 under the Plan; includes 28,000
     shares as to which the January option is exercisable.
(12)  Mr. Wiest is the Chief Operating Officer of ATC. His address is 116
      Huntington Avenue, Boston, Massachusetts 02116. Includes 35,556 shares
      of Class A common stock owned by Mr. Wiest. Does not include 192,000
      shares of Class A common stock purchasable under an option granted on
      January 22, 1998 under the Plan and 125,000 shares of Class A common
      stock purchasable under an option granted on December 1, 1998 under the
      Plan; includes 48,001 shares as to which the January option is
      exercisable.
(13)  Ms. Wilderotter is a director of ATC. Her address is 116 Huntington
      Avenue, Boston, Massachusetts 02116. Does not include 25,000 shares of
      Class A common stock purchasable under an option granted on
 
                                      36
<PAGE>
 
    June 22, 1998 under the Plan and 25,000 shares of Class A common stock
    purchasable under an option granted on December 1, 1998 under the Plan.
(14) Mr. Winn is the Treasurer and Chief Financial Officer of ATC. His address
     is 116 Huntington Avenue, Boston, Massachusetts 02116. Includes 2,000
     shares of Class A common stock and 230,657 shares of Class B common stock
     owned individually by Mr. Winn and 100 shares of Class A Common Stock
     held for the benefit of his children. Does not include an aggregate of
     81,292 shares of Class B common stock and 15,048 shares of Class A common
     stock purchasable under ATC options received in exchange for American
     Radio options upon consummation of the ATC Separation; includes an
     aggregate of 120,037 shares of Class B common stock and 10,032 shares of
     Class A common stock as to which such options are exercisable. Does not
     include 220,000 shares of Class A common stock purchasable under an
     option granted on January 8, 1998 under the Plan, 210,000 shares of Class
     A common stock purchasable under an option granted on June 22, 1998 under
     the Plan and 125,000 shares of Class A common stock purchasable under an
     option granted on December 1, 1998 under the Plan; includes 55,000 shares
     as to which the January option is exercisable.
(15)  Includes all shares stated to be owned in the preceding notes.
(16) The address of Wellington Management Company, LLP ("Wellington") is 75
     State Street, Boston, Massachusetts 02109. Based on Wellington's Schedule
     13G dated February 9, 1999, Wellington has sole voting power over 0
     shares of Class A common stock, shared voting power over 5,497,887 shares
     of Class A common stock, sole dispositive power over 0 shares of Class A
     common stock and shared dispositive power over 8,031,887 shares of Class
     A common stock.
 
ITEM 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS
 
  Chase was a lender with a 6.75% participation under the loan agreement
entered into by ATI and has a 5.2% participation under the Credit Facilities
for the Borrower Subsidiaries. Chase is an affiliate of CCP, the general
partner of CEA; Mr. Chavkin, a director of ATC, is a general partner of CCP.
At December 31, 1998, the aggregate principal amount outstanding under the
Credit Facilities of ATC and the Borrower Subsidiaries was $275.0 million.
Chase's share of interest and fees paid by ATC pursuant to its various credit
arrangements was $0.2 million and $0.8 million in 1997 and 1998, respectively.
 
  Mr. Eisenstein received $1,022,366 demand loan in August 1998. In December
1998, Mr. Eisenstein repaid $700,000, and as of December 31, 1998, such loan
bore interest at a fixed rate and remained outstanding in the principal amount
of $322,366. See "--Executive Compensation" in Item 11.
 
  ATC Private Placement. In January 1998, ATC consummated the transactions
contemplated by the Stock Purchase Agreement, dated as of January 8, 1998 (the
"Stock Purchase Agreement"), with certain officers and directors of American
Radio and ATC (or their affiliates or members of their family or family
trusts), pursuant to which those persons purchased shares (the "ATC Private
Placement") of Common Stock at $10.00 per share, as follows: Mr. Dodge:
4,000,000 (Class B); Mr. Box: 450,000 (Class A); Mr. Charlton H. Buckley:
300,000 (Class A); each of Messrs. Eisenstein and Steven J. Moskowitz: 25,000
(Class A); Mr. Arthur Kellar: 400,000 (Class A); Mr. Stoner, his wife and
certain family trusts: 649,950 (Class B); other Stoner family and trust
purchasers: 150,050 (Class A); and CEA: 2,000,000 (Class C). Messrs. Buckley
and Kellar were directors of American Radio, and Mr. Chavkin, a director of
ATC and a former director of American Radio, is an affiliate of CEA. Mr.
Moskowitz serves as Executive Vice President--Marketing of ATC and the General
Manager of the Northeast Region.
 
  Payment of the purchase price was in the form of cash in the case of CEA,
all members of Mr. Stoner's family and the family trusts (but not Mr. Stoner
and his wife) and Messrs. Buckley, Eisenstein, Kellar and Moskowitz, and, in
the case of Messrs. Dodge, Box and Stoner (and his wife), in the form of a
note that was paid in full upon consummation of the ATC Separation. The notes
bore interest at the six-month LIBOR, from time to time, plus 1.5% per annum,
and were secured by shares of American Radio common stock having a fair market
value of not less than 175% of the principal amount of and accrued and unpaid
interest on the note. The notes were prepayable at any time at the option of
the obligor and were due and payable, at the option of ATC, in the event of
certain defaults set forth therein.
 
                                      37
<PAGE>
 
  The American Radio Board of Directors appointed a special committee (the
"Special Committee") consisting of three directors (who were not directors of
ATC and who were not a party to the Stock Purchase Agreement) to determine the
fairness to American Radio from a financial point of view of the terms and
conditions of the Stock Purchase Agreement. None of the members of the Special
Committee was a party to the Stock Purchase Agreement. No limitations were
imposed on the activities of the Special Committee by the American Radio
Board. The Special Committee retained Merrill Lynch, Pierce, Fenner & Smith
Incorporated ("Merrill Lynch") to act as its exclusive financial advisor in
connection with the transactions contemplated by the Stock Purchase Agreement.
No limitations were placed on the activities of Merrill Lynch. Merrill Lynch
delivered its written opinion, dated January 8, 1998, to the Special Committee
that, as of such date and based upon and subject to the matters set forth
therein, the purchase price of $10.00 per share to be received by ATC pursuant
to the Stock Purchase Agreement was fair from a financial point of view to
American Radio. Based upon such opinion, and its own evaluation of the terms
and conditions of the ATC Stock Purchase Agreement, the Special Committee
approved the Stock Purchase Agreement as fair to and in the best interests of
American Radio.
 
  Pursuant to an Engagement Letter, dated November 20, 1997, American Radio
agreed to pay Merrill Lynch a fee of $500,000 in consideration for its
services. American Radio has also agreed to reimburse Merrill Lynch for its
expenses, including reasonable fees and expenses of its counsel, and to
indemnify Merrill Lynch for liabilities and expenses arising out of its
engagement and the transactions in connection therewith, including liabilities
under the federal securities laws. ATC is obligated under the Separation
Agreement to reimburse American Radio for all such fees and expenses which
American Radio has incurred to Merrill Lynch and to assume such
indemnification obligation.
 
  Management believes that the above transactions, to the extent they were
with affiliated parties, were on terms, and ATC intends to continue its policy
that all future transactions between it and its officers, directors, principal
stockholders and affiliates will be on terms, not less favorable to ATC than
those which could be obtained from unaffiliated parties.
 
                                      38
<PAGE>
 
                                   PART IV.
 
ITEM 14. EXHIBITS, FINANCIAL STATEMENT SCHEDULES AND REPORTS ON FORM 8-K.
 
(a) Documents filed as part of this report.
 
(1) Financial Statements
<TABLE>
<CAPTION>
                                                                           Page
                                                                           ----
<S>                                                                        <C>
AMERICAN TOWER CORPORATION AND SUBSIDIARIES
  Independent Auditors' Report............................................ F-1
  Consolidated Balance Sheets as of December 31, 1998 and 1997............ F-2
  Consolidated Statements of Operations for the years ended December 31,
   1998, 1997 and 1996.................................................... F-3
  Consolidated Statements of Stockholders' Equity for the years ended
   December 31, 1998, 1997 and 1996....................................... F-4
  Consolidated Statements of Cash Flows for the years ended December 31,
   1998, 1997 and 1996.................................................... F-5
  Notes to Consolidated Financial Statements.............................. F-6
(b) Reports on Form 8-K.
  Form 8-K (Items 2 and 7) filed on November 30, 1998.
(c) Exhibits.--See Exhibit Index.
(d) Index to Financial Statement Schedules.
</TABLE>
 
   All schedules have been omitted because the required information either is
   not applicable or is shown in or determinable from the consolidated
   financial statements or notes thereto.
 
                                      39
<PAGE>
 
                                  SIGNATURES
 
  Pursuant to the requirements of section 13 or 15(d) of the Securities
Exchange Act of 1934, the Registrant has duly caused this report to be signed
on its behalf by the undersigned, thereunto duly authorized on the 19th day of
March 1999.
 
                                          American Tower Corporation
 
                                                    /s/ Steven B. Dodge
                                          By: _________________________________
                                              Steven B. Dodge Chief Executive
                                             Officer, Director, President and
                                                   Chairman of the Board
 
  Pursuant to the requirements of the Securities Exchange Act of 1934, this
report has been signed below by the following persons on behalf of the
Registrant and in the capacities and on the dates indicated:
 
<TABLE>
<S>  <C>
         Signature                        Title
                                                                     Date
 
    /s/ Steven B. Dodge              Chairman of the Board,     March 19, 1999
- ---------------------------           Chief Executive Officer,
       Steven B. Dodge                President and Director
 
/s/ Joseph L. Winn                   Chief Financial Officer    March 19, 1999
- ---------------------------
       Joseph L. Winn
 
/s/ Alan L. Box                      Executive Vice President   March 19, 1999
- ---------------------------           and Director
         Alan L. Box
 
/s/ Justin D. Benincasa              Vice President and Corporate
                                      Controller
                                                                March 19, 1999
- ---------------------------
     Justin D. Benincasa
 
   /s/ Thomas H. Stoner              Director                   March 19, 1999
- ---------------------------
      Thomas H. Stoner
 
/s/ Dean H. Eisner                   Director                   March 19, 1999
- ---------------------------
       Dean H. Eisner
 
/s/ Jack D. Furst                    Director                   March 19, 1999
- ---------------------------
        Jack D. Furst
</TABLE>
 
                                      40
<PAGE>
 
<TABLE>
<S>  <C>
</TABLE>
         Signature                    Title                          Date
 
   /s/ Arnold L. Chavkin             Director                   March 19, 1999
- ---------------------------
     Arnold L. Chavkin
 
     /s/ Randall Mays                Director                   March 19, 1999
- ---------------------------
       Randall Mays
 
/s/ Maggie Wilderotter               Director                   March 19, 1999
- ---------------------------
    Maggie Wilderotter
 
/s/ J. Michael Gearon, Jr.           Executive Vice President, Site
                                      Acquisition Services and
                                      Director
                                                                March 19, 1999
- ---------------------------
  J. Michael Gearon, Jr.
 
    /s/ Fred R. Lummis               Director                   March 19, 1999
- ---------------------------
      Fred R. Lummis
 
 
                                       41
<PAGE>
 
                         INDEPENDENT AUDITORS' REPORT
 
To the Board of Directors of
American Tower Corporation:
 
We have audited the accompanying consolidated balance sheets of American Tower
Corporation and subsidiaries (the "Company") as of December 31, 1998 and 1997,
and the related consolidated statements of operations, stockholders' equity,
and cash flows for each of the three years in the period ended December 31,
1998. These financial statements are the responsibility of the Company's
management. Our responsibility is to express an opinion on these financial
statements based on our audits.
 
We conducted our audits in accordance with generally accepted auditing
standards. Those standards require that we plan and perform the audit to
obtain reasonable assurance about whether the financial statements are free of
material misstatement. An audit includes examining, on a test basis, evidence
supporting the amounts and disclosures in the financial statements. An audit
also includes assessing the accounting principles used and significant
estimates made by management, as well as evaluating the overall financial
statement presentation. We believe that our audits provide a reasonable basis
for our opinion.
 
In our opinion, such consolidated financial statements present fairly, in all
material respects, the consolidated financial position of the Company as of
December 31, 1998 and 1997, and the results of its operations and its cash
flows for each of the three years in the period ended December 31, 1998 in
conformity with generally accepted accounting principles.
 
Deloitte & Touche LLP
Boston, Massachusetts
March 4, 1999
 
                                      F-1
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
                          CONSOLIDATED BALANCE SHEETS
 
                           December 31, 1998 and 1997
                       (In thousands, except share data)
 
<TABLE>
<CAPTION>
                                                             1998       1997
                                                          ----------  --------
<S>                                                       <C>         <C>
ASSETS
CURRENT ASSETS:
 Cash and cash equivalents............................... $  186,175  $  4,596
 Accounts receivable, net................................     15,506     3,239
 Unbilled receivables....................................      1,344
 Prepaid and other current assets........................      4,065       790
 Deferred income taxes...................................        495        63
                                                          ----------  --------
   Total current assets..................................    207,585     8,688
                                                          ----------  --------
PROPERTY AND EQUIPMENT, net..............................    449,476   117,618
GOODWILL AND OTHER INTANGIBLE ASSETS, net................    718,575   116,616
NOTES RECEIVABLE.........................................      7,585    10,700
DEPOSITS AND OTHER LONG-TERM ASSETS......................      9,704     1,735
DEFERRED INCOME TAXES....................................    109,418
                                                          ----------  --------
TOTAL.................................................... $1,502,343  $255,357
                                                          ==========  ========
LIABILITIES AND STOCKHOLDERS' EQUITY
CURRENT LIABILITIES:
 Current portion of long-term debt....................... $    1,652  $    110
 Accounts payable........................................      6,696     3,738
 Accrued expenses........................................     11,347     4,213
 Accrued tower construction costs........................     16,099       279
 Accrued interest........................................      1,132       914
 Unearned income.........................................      6,610     1,752
 Accrued separation expenses.............................      5,058
 Due to CBS Corporation..................................     45,127
 Accrued acquisition purchase price......................     21,914
                                                          ----------  --------
   Total current liabilities.............................    115,635    11,006
                                                          ----------  --------
LONG-TERM DEBT...........................................    279,477    90,066
DEFERRED INCOME TAXES....................................                  418
OTHER LONG-TERM LIABILITIES..............................      1,429        33
                                                          ----------  --------
   Total liabilities.....................................    396,541   101,523
                                                          ----------  --------
COMMITMENTS AND CONTINGENCIES (Notes 5 and 12)
MINORITY INTEREST IN SUBSIDIARIES........................      4,116       626
                                                          ----------  --------
REDEEMABLE CLASS A COMMON STOCK- $.01 par value, 336,250
 shares issued and outstanding at estimated redemption
 value of $29.5625 per share.............................      9,940
                                                          ----------  --------
STOCKHOLDERS' EQUITY:
 Preferred Stock; $0.01 par value; 20,000,000 shares
  authorized; no shares issued or outstanding............
 Class A Common Stock; $.01 par value; 300,000,000
  shares authorized; 96,291,111 shares and 29,667,883
  shares issued and outstanding, respectively............        963       297
 Class B Common Stock; $.01 par value; 50,000,000 shares
  authorized; 9,001,060 shares and 4,670,626 shares
  issued and outstanding, respectively...................         90        47
 Class C Common Stock; $.01 par value; 10,000,000 shares
  authorized; 3,002,008 shares and 1,295,518 shares
  issued and outstanding, respectively...................         30        13
 Additional paid-in capital..............................  1,140,365   155,711
 Accumulated deficit.....................................    (49,702)   (2,860)
                                                          ----------  --------
   Total stockholders' equity............................  1,091,746   153,208
                                                          ----------  --------
TOTAL.................................................... $1,502,343  $255,357
                                                          ==========  ========
</TABLE>
                See notes to consolidated financial statements.
 
                                      F-2
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
                     CONSOLIDATED STATEMENTS OF OPERATIONS
 
  Years Ended December 31, 1998, 1997 and 1996(In thousands, except per share
                                     data)
 
<TABLE>
<CAPTION>
                                                    Years Ended December 31,
                                                    --------------------------
                                                      1998     1997     1996
                                                    --------  -------  -------
<S>                                                 <C>       <C>      <C>
REVENUES:
  Tower rental and management (See Note 6 for
   related party amounts) ........................  $ 60,505  $13,302  $ 2,897
  Services........................................    23,315    2,122
  Video, voice, data and Internet transmission....    19,724    2,084
                                                    --------  -------  -------
    Total operating revenues......................   103,544   17,508    2,897
                                                    --------  -------  -------
OPERATING EXPENSES:
  Operating expenses excluding depreciation and
   amortization, tower separation expenses and
   corporate general and administrative expenses:
   Tower rental and management....................    29,455    6,080    1,362
   Services.......................................    19,479    1,360
   Video, voice, data and Internet transmission...    12,817    1,273
  Depreciation and amortization...................    52,064    6,326      990
  Tower separation expenses.......................    12,772
  Corporate general and administrative expenses...     5,099    1,536      830
                                                    --------  -------  -------
    Total operating expenses......................   131,686   16,575    3,182
                                                    --------  -------  -------
INCOME (LOSS) FROM OPERATIONS.....................   (28,142)     933     (285)
                                                    --------  -------  -------
OTHER INCOME (EXPENSE):
  Interest expense (See Note 6 for related party
   amounts) ......................................   (23,229)  (3,040)
  Interest income and other, net..................     9,217      251       36
  Minority interest in net earnings of
   subsidiaries...................................      (287)    (193)    (185)
                                                    --------  -------  -------
TOTAL OTHER EXPENSE...............................   (14,299)  (2,982)    (149)
                                                    --------  -------  -------
LOSS BEFORE BENEFIT (PROVISION) FOR INCOME TAXES
 AND EXTRAORDINARY LOSSES.........................   (42,441)  (2,049)    (434)
BENEFIT (PROVISION) FOR INCOME TAXES..............     4,491      473      (45)
                                                    --------  -------  -------
LOSS BEFORE EXTRAORDINARY LOSSES..................   (37,950)  (1,576)    (479)
EXTRAORDINARY LOSS ON EXTINGUISHMENT OF DEBT, NET
 OF INCOME TAX BENEFIT OF $921 IN 1998 AND $463 IN
 1997.............................................    (1,382)    (694)
EXTRAORDINARY LOSS ON REDEMPTION OF INTERIM
 PREFERRED STOCK, NET OF INCOME TAX BENEFIT OF
 $5,000...........................................    (7,510)
                                                    --------  -------  -------
NET LOSS..........................................  $(46,842) $(2,270) $  (479)
                                                    ========  =======  =======
BASIC AND DILUTED LOSS PER COMMON SHARE AMOUNTS:
  Loss before extraordinary losses................  $  (0.48) $ (0.03) $ (0.00)
  Extraordinary losses............................     (0.11)   (0.01)
                                                    --------  -------  -------
  Net loss........................................  $  (0.59) $ (0.05) $ (0.00)
                                                    ========  =======  =======
WEIGHTED AVERAGE NUMBER OF COMMON SHARES
 OUTSTANDING......................................    79,786   48,732   48,732
                                                    ========  =======  =======
</TABLE>
 
                See notes to consolidated financial statements.
 
                                      F-3
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
                CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY
 
  Years Ended December 31, 1998 and 1997 and 1996 (In thousands, except share
                                     data)
 
<TABLE>
<CAPTION>
                      Common Stock      Common Stock        Common Stock       Common Stock
                   ------------------ ------------------ ------------------ ------------------
                                           Class A            Class B            Class C
                                      ------------------ ------------------ ------------------            Additional
                   Outstanding        Outstanding        Outstanding        Outstanding          Notes     Paid-in    Accumulated
                     Shares    Amount   Shares    Amount   Shares    Amount   Shares    Amount Receivable  Capital      Deficit
                   ----------- ------ ----------- ------ ----------- ------ ----------- ------ ---------- ----------  -----------
<S>                <C>         <C>    <C>         <C>    <C>         <C>    <C>         <C>    <C>        <C>         <C>
BALANCE, JANUARY
 1, 1996.........        10     $--                                                                       $    3,880   $   (111)
Issuance of
 common stock to
 ARS.............     2,990
Contributions
 from ARS:
 Cash............                                                                                              2,549
 Non-cash........                                                                                             29,855
Transfers to ARS:
 Cash............                                                                                             (4,866)
 Non-cash........                                                                                             (1,100)
Net loss.........                                                                                                          (479)
                     ------     ----                                                                      ----------   --------
BALANCE, DECEMBER
 31, 1996........     3,000                                                                                   30,318       (590)
Contributions
 from ARS:
 Cash............                                                                                            143,073
 Non-cash........                                                                                                 51
Transfers to ARS:
 Cash............                                                                                            (16,650)
 Non-cash........                                                                                               (724)
Recapitalization
 (Note 8)........    (3,000)          29,667,883   $297   4,670,626   $ 47   1,295,518   $ 13                   (357)
Net loss.........                                                                                                        (2,270)
                     ------     ----  ----------   ----   ---------   ----   ---------   ----             ----------   --------
BALANCE, DECEMBER
 31, 1997........       --       --   29,667,883    297   4,670,626     47   1,295,518     13                155,711     (2,860)
                     ======     ====
Contributions
 from ARS:
 Cash............                                                                                             56,918
 Non-cash........                                                                                              6,489
Transfers to ARS:
 Cash............                                                                                            (51,858)
Issuance of com-
 mon stock under
 stock purchase
 agreement, net
 of issuance
 costs of $630...                      1,350,050     14   4,649,950     46   2,000,000     20   $(49,375)     79,290
Issuance of com-
 mon stock-Gearon
 merger..........                      5,333,333     53                                                       47,947
Reduction of com-
 mon stock re-
 demption obliga-
 tion............                        383,750      4                                                        9,740
Issuance of com-
 mon stock-ATC
 merger..........                     28,782,386    287                                                      297,192
Issuance of com-
 mon stock-Wauka
 merger..........                      1,430,881     14                                                       28,603
Exercise of op-
 tions...........                        899,504      9     203,709      2                                     2,727
Repayment stock
 purchase agree-
 ment notes......                                                                                 49,375
ATC Separation
 tax liability...                                                                                            (61,715)
ATC Separation
 working capital
 adjustment......                                                                                            (50,000)
ATC Separation
 share conver-
 sion............                        111,761      1    (347,159)    (3)                                        2
Issuance of com-
 mon stock - July
 offering, net of
 issuance costs
 of $29,806......                     27,861,987    279                                                      624,672
Share Class Ex-
 changes.........                        469,576      5    (176,066)    (2)   (293,510)    (3)
Accretion of Re-
 deemable Stock..                                                                                             (1,555)
Tax liability
 from conversion
 of CBS securi-
 ties............                                                                                             (5,021)
Tax benefit of
 stock options...                                                                                              1,223
Net loss.........                                                                                                       (46,842)
                                      ----------   ----   ---------   ----   ---------   ----   --------  ----------   --------
BALANCE, DECEMBER
 31, 1998........                     96,291,111   $963   9,001,060   $ 90   3,002,008   $ 30   $      0  $1,140,365   $(49,702)
                                      ==========   ====   =========   ====   =========   ====   ========  ==========   ========
<CAPTION>
                     Total
                   -----------
<S>                <C>
BALANCE, JANUARY
 1, 1996.........  $    3,769
Issuance of
 common stock to
 ARS.............
Contributions
 from ARS:
 Cash............       2,549
 Non-cash........      29,855
Transfers to ARS:
 Cash............      (4,866)
 Non-cash........      (1,100)
Net loss.........        (479)
                   -----------
BALANCE, DECEMBER
 31, 1996........      29,728
Contributions
 from ARS:
 Cash............     143,073
 Non-cash........          51
Transfers to ARS:
 Cash............     (16,650)
 Non-cash........        (724)
Recapitalization
 (Note 8)........
Net loss.........      (2,270)
                   -----------
BALANCE, DECEMBER
 31, 1997........     153,208
Contributions
 from ARS:
 Cash............      56,918
 Non-cash........       6,489
Transfers to ARS:
 Cash............     (51,858)
Issuance of com-
 mon stock under
 stock purchase
 agreement, net
 of issuance
 costs of $630...      29,995
Issuance of com-
 mon stock-Gearon
 merger..........      48,000
Reduction of com-
 mon stock re-
 demption obliga-
 tion............       9,744
Issuance of com-
 mon stock-ATC
 merger..........     297,479
Issuance of com-
 mon stock-Wauka
 merger..........      28,617
Exercise of op-
 tions...........       2,738
Repayment stock
 purchase agree-
 ment notes......      49,375
ATC Separation
 tax liability...     (61,715)
ATC Separation
 working capital
 adjustment......     (50,000)
ATC Separation
 share conver-
 sion............           0
Issuance of com-
 mon stock - July
 offering, net of
 issuance costs
 of $29,806......     624,951
Share Class Ex-
 changes.........
Accretion of Re-
 deemable Stock..      (1,555)
Tax liability
 from conversion
 of CBS securi-
 ties............      (5,021)
Tax benefit of
 stock options...       1,223
Net loss.........     (46,842)
                   -----------
BALANCE, DECEMBER
 31, 1998........  $1,091,746
                   ===========
</TABLE>
 
                See notes to consolidated financial statements.
 
                                      F-4
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
                     CONSOLIDATED STATEMENTS OF CASH FLOWS
 
                  Years Ended December 31, 1998, 1997 and 1996
                                 (In thousands)
 
<TABLE>
<CAPTION>
                                                  Years Ended December 31,
                                                ------------------------------
                                                  1998      1997       1996
                                                --------  ---------  ---------
<S>                                             <C>       <C>        <C>
CASH FLOWS FROM OPERATING ACTIVITIES:
 Net loss...................................... $(46,842) $  (2,270) $    (479)
 Adjustments to reconcile net loss to cash
  provided by operating activities:
 Depreciation and amortization.................   52,064      6,326        990
 Minority interest in net earnings of
  subsidiaries.................................      287        193        185
 Amortization of deferred financing costs......    1,629        188
 Provision for losses on accounts receivable...    1,136        124         47
 Extraordinary losses, net.....................    8,892        694
 Amortization of debt discount.................      261
 Dividends on Interim Preferred Stock..........    3,117
 Deferred income taxes.........................   (4,491)       147        109
 Changes in assets and liabilities, net of
  acquisitions:
   Accounts receivable.........................  (11,042)    (3,156)      (247)
   Unbilled receivables........................   (1,185)
   Prepaid and other current assets............   (1,553)       159       (227)
   Accounts payable and accrued expenses.......   13,577      5,080      1,580
   Accrued interest............................      (47)       914
   Unearned income.............................    1,311      1,500        253
   Other long-term liabilities.................    1,315         14         19
                                                --------  ---------  ---------
Cash provided by operating activities..........   18,429      9,913      2,230
                                                --------  ---------  ---------
CASH FLOWS FROM INVESTING ACTIVITIES:
 Payments for purchase of property and
  equipment
  and construction activities.................. (126,455)   (20,614)
 Payments for acquisitions..................... (208,717)  (184,076)
 Advances of notes receivable..................  (12,140)   (10,962)
 Proceeds from repayment of notes receivable...    2,001
 Deposits and other long-term assets...........   (5,066)    (1,131)
                                                --------  ---------  ---------
Cash used for investing activities............. (350,377)  (216,783)
                                                --------  ---------  ---------
CASH FLOWS FROM FINANCING ACTIVITIES:
 Borrowings under credit facilities............  205,500    151,000      2,500
 Repayments of other notes payable and credit
  facilities................................... (156,667)   (65,359)      (107)
 Net proceeds from equity offerings and stock
  options......................................  707,059
 Cash transfers to CBS Corporation............. (221,665)
 Borrowings under other notes payable..........                            231
 Net proceeds from Interim Preferred Stock.....  300,000
 Redemption of Interim Preferred Stock......... (303,117)
 Contributions from ARS........................   56,918    143,073      2,549
 Cash transfers to ARS.........................  (51,858)   (16,650)    (4,866)
 Distributions to minority interest............     (393)      (419)      (175)
 Additions to deferred financing costs.........  (22,250)    (2,553)
                                                --------  ---------  ---------
Cash provided by financing activities..........  513,527    209,092        132
                                                --------  ---------  ---------
NET INCREASE IN CASH AND CASH EQUIVALENTS......  181,579      2,222      2,362
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR...    4,596      2,374         12
                                                --------  ---------  ---------
CASH AND CASH EQUIVALENTS, END OF YEAR......... $186,175  $   4,596  $   2,374
                                                ========  =========  =========
</TABLE>
 
                See notes to consolidated financial statements.
 
                                      F-5
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
                  NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
 
1. BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
 
Business and Corporate Structure--American Tower Corporation and subsidiaries
(collectively, ATC or the Company) (formerly American Tower Systems
Corporation) was a wholly-owned subsidiary of American Radio Systems
Corporation (ARS, American Radio or the Former Parent) until consummation of
the spin-off of ATC from American Radio on June 4, 1998 (the ATC Separation).
American Tower, Inc. (ATI) is a wholly-owned subsidiary of the ATC which holds
substantially all the operating assets and liabilities of the business.
American Tower, L.P. (ATLP) is an indirect wholly-owned subsidiary of ATC. ATI
and ATLP are collectively referred to as the Borrower Subsidiaries.
 
The Company was incorporated on July 17, 1995 (Incorporation) for the purpose
of acquiring, developing, marketing, managing and operating wireless
communications tower sites throughout the United States, for use by wireless
communications providers and television and radio broadcasters.
 
As of December 31, 1998, the Company owned and/or operated approximately 2,300
wireless communication sites. Based in Boston, the Company operates throughout
the United States with regional hubs in Boston, Albuquerque, Atlanta, Chicago,
Houston and San Francisco. ATC's primary business is the leasing of antennae
sites on multi-tenant towers for a diverse range of wireless communications
industries, including personal communications services, cellular, paging,
specialized mobile radio, enhanced specialized mobile radio and fixed
microwave, as well as radio and television broadcasters. ATC also offers its
customers a broad range of network development services, including network
design, site acquisition, zoning and other regulatory approvals, tower
construction and antennae installation. ATC intends to expand these services
and to capitalize on its relationships with its wireless customers through
major built to suit construction projects. ATC is also engaged in the video,
voice, data and Internet transmission business, which it currently conducts in
the New York City to Washington, D.C. corridor and in Texas.
 
ATC Separation:  On June 4, 1998, the merger of American Radio and a
subsidiary of CBS Corporation (CBS) was consummated. As a consequence, all of
the shares of ATC Common Stock (the Common Stock) owned by ARS were
distributed to ARS common stockholders and holders of options to acquire ARS
Common Stock or will be distributed upon conversion of shares of ARS 7%
Convertible Exchangeable Preferred Stock (the Convertible Preferred Stock). As
a consequence of the ATC Separation, ATC ceased to be a subsidiary of, or to
be otherwise affiliated with American Radio and now operates as an independent
publicly traded company. Pursuant to the provisions of the CBS merger
agreement, ATC entered into an agreement (the Separation Agreement) with CBS
and ARS providing for, among other things, the orderly separation of ARS and
ATC, the allocation of certain tax liabilities, as a result of the separation,
to ATC and certain closing date adjustments relating to ARS.
 
The Separation Agreement requires ATC to reimburse CBS on a "make-whole"
(after tax) basis for the tax liabilities incurred by ARS attributable to the
distribution of the Common Stock owned by ARS to the ARS security holders and
certain related transactions to the extent that the aggregate amount of taxes
required to be paid by ARS exceeded $20.0 million. The amount of that tax
liability was dependent on the "fair market value" of the Common Stock at the
time of the consummation of the ATC Separation. ATC received an appraisal from
an independent appraisal firm that the "fair market value" of ARS's stock
interest in ATC was equal to $17.25 per share. Based on such appraisal, ARS
paid estimated taxes of approximately $212.0 million and was reimbursed
therefore by ATC. As required by the Separation Agreement, ATC provided CBS
with security of $9.8 million in cash (which may be replaced at ATC's option
with a letter of credit reasonably satisfactory to CBS) in connection with the
filing of estimated tax returns based on such appraisal. Such appraisal is
not, of course, binding on the Internal Revenue Service or other taxing
authorities. The Company financed its tax reimbursement obligations to CBS
with the proceeds from the issuance of Interim Preferred Stock as discussed
 
                                      F-6
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)
 
in Note 8. The $212.0 million payment also included estimated payments for the
"make-whole" provisions of the liability associated with the conversion of the
Convertible Preferred Stock and the working capital and debt level adjustments
described below.
 
Such taxes gave effect to estimated deductions of approximately $85.1 million
available to ARS as a consequence of the cancellation or exercise of ARS stock
options pursuant to the ATC Separation. ATC's reimbursement obligation with
respect to such taxes would change by approximately $21.0 million for each
$1.00 change in the "fair market value" of the Class A Common Stock under the
tax reporting method followed. The average of the high and low trading prices
of the Class A Common Stock in the when-issued over-the-counter market on June
4, 1998 was $20.50.
 
The $212.0 million payment did not include all the taxes payable with respect
to the shares of Class A Common Stock deliverable upon conversion of the ARS
Convertible Preferred; such taxes will be based on the "fair market value" of
the Class A Common Stock at the time of conversion. Conversions have occurred
at various times since June 4, 1998. On September 30, 1998, CBS issued
convertible debentures (the ARS Convertible Debentures) in exchange for the
then outstanding shares of ARS Convertible Preferred. Holders of the ARS
Convertible Debentures are entitled to the same conversion rights as the ARS
Convertible Preferred. As of December 31, 1998 holders of 47% of the ARS
Convertible Preferred and/or ARS Convertible Debentures had converted or
presented for conversion. As of December 31, 1998, ATC estimates that its
reimbursement obligation with respect to taxes on known conversions is
approximately $13.5 million, of which $8.5 million has been paid. ATC
estimates that its remaining reimbursement obligation with respect to the
taxes on ARS Convertible Debentures that had not then been converted would be
approximately $19.1 million under the tax reporting method followed. Such
estimate is based on an estimated fair market value of the Class A Common
Stock of $28.75 per share. ATC's obligation for such conversions would change
by approximately $1.1 million for each $1.00 change in such fair market value.
 
American Radio has agreed that it will pursue, for the benefit of and at the
cost of ATC, a refund claim, attributable to the "make-whole" provision,
estimated at between $40.0 million to $45.0 million, based on the appraised
"fair market value" and the estimated taxes attributable to conversions of the
ARS Convertible Debentures set forth above. Any such refund claim will, in
fact, be based on the actual amount of taxes paid. In light of existing tax
law, any such refund claim may not be successful.
 
The Separation Agreement also provided for closing balance sheet adjustments
based on the working capital, as defined, and debt levels of American Radio as
of June 4, 1998. ATC's preliminary June 1998 estimate was that such
adjustments would not exceed $50.0 million, excluding the reimbursement to CBS
for the tax consequences of any such payment (estimated at approximately $33.0
million) which was paid in connection with the $212.0 million payment to CBS
referred to above. In February 1999, ATC paid CBS $50.0 million in settlement
of all amounts due with respect to such adjustments, including interest. As
part of such settlement, ATC also agreed to indemnify CBS and American Radio
with respect to certain tax matters affecting American Radio prior to the ATC
Separation.
 
Corporate Tax Restructuring--In connection with an inter-corporate taxable
transfer of assets entered into in January 1998 by ATC in contemplation of the
separation of ATC and ARS, a portion of the tax with respect to which ATC was
obligated to indemnify CBS has been incurred. Such transfer resulted in an
increase in the tax bases of ATC's assets of approximately $390.0 million. ATC
recorded a deferred tax asset of approximately $150.2 million and will have
potential depreciation and amortization deductions over the next 15 years.
(See Note 7).
 
Principles of Consolidation and Basis of Presentation--The accompanying
consolidated financial statements include the accounts of the Company and its
subsidiaries. All significant intercompany accounts and transactions have been
eliminated. Investments in affiliates, where ATC owns more than 20 percent of
the voting power of
 
                                      F-7
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)
 
the affiliate but not in excess of 50 percent, are accounted for using the
equity method. Separate financial information regarding equity method
investees is not significant. The Company also consolidates its greater than
50 percent interests in other tower communications companies, with the other
members' investments reflected as minority interest in subsidiaries in the
accompanying consolidated financial statements.
 
Through June 4, 1998, ATC effectively operated as a stand-alone entity, with
its own corporate staff and headquarters, and received minimal assistance from
personnel of ARS. Accordingly, the accompanying consolidated financial
statements do not include any corporate general and administrative cost
allocations from ARS. However, the consolidated financial statements may not
reflect the results of operations or financial position of ATC had it been an
independent public company during the periods presented.
 
Use of Estimates--The preparation of financial statements in conformity with
generally accepted accounting principles requires management to make estimates
and assumptions that affect the amounts reported in the financial statements
and accompanying notes. Actual results may differ from those estimates, and
such differences could be material to the accompanying consolidated financial
statements.
 
Revenue Recognition--Tower rental and management revenues are recognized when
earned. Escalation clauses and other incentives present in tower lease
agreements with the Company's customers are recognized on a straight-line
basis over the term of the lease. Service revenues from site selection and
construction management activities are recognized under service contracts with
customers which provide for billings on a time and materials or fixed price
basis. Revenues are recognized as services are performed with respect to the
time and materials contracts. Revenues are recognized using the percentage-of-
completion method for fixed price contracts, measured by the percentage of
contract costs incurred to date compared to estimated total contract costs.
Provisions for estimated losses on uncompleted contracts are made in the
period in which such losses are determined. Other service revenues and video,
voice, data and Internet transmission revenues are recognized as such services
are provided. Amounts billed or received prior to services being performed are
deferred until such time as the revenue is earned.
 
Corporate General and Administrative Expense--Corporate general and
administrative expense consists of corporate overhead costs not specifically
allocable to any of the Company's individual business properties.
 
Concentration of Credit Risk--Financial instruments that potentially subject
the Company to concentrations of credit risk are primarily cash and cash
equivalents and notes and trade receivables. The Company mitigates its risk
with respect to cash and cash equivalents by maintaining such deposits at high
credit quality financial institutions and monitoring the credit ratings of
those institutions.
 
The Company derives the largest portion of its revenues from customers in the
wireless telecommunications industry. In addition, the Company has
concentrations of operations in certain geographic areas (primarily
California, Florida and Texas). The Company mitigates its concentration of
credit risk with respect to trade receivables by actively monitoring the
creditworthiness of its customers. Historically, the Company has not incurred
any significant credit related losses.
 
Accounts receivable are reported net of allowances for doubtful accounts of
$1,230,000 and $125,000 as of December 31, 1998 and 1997, respectively.
Accounts charged off to the allowance for doubtful accounts aggregated
$206,000, $46,000 and $0 for the years ended December 31, 1998, 1997 and 1996,
respectively.
 
Derivative Financial Instruments--The Company uses derivative financial
instruments as a means of managing interest-rate risk associated with current
debt or anticipated debt transactions that have a high probability of being
executed. The Company's interest rate protection agreements generally consist
of interest rate swap agreements and interest rate cap agreements. These
instruments are matched with either fixed or variable rate debt, and
 
                                      F-8
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)
 
payments thereon are recorded on a settlement basis as an adjustment to
interest expense. Premiums paid to purchase interest rate cap agreements are
amortized as an adjustment of interest expense over the life of the contract.
Derivative financial instruments are not held for trading purposes. (See Note
4).
 
Cash and Cash Equivalents--Cash and cash equivalents include cash on hand,
demand deposits and short-term investments with remaining maturities when
purchased of three months or less.
 
Property and Equipment--Property and equipment are recorded at cost, or at
estimated fair value in the case of acquired properties. Cost includes
expenditures for communications sites and related assets and the net amount of
interest cost associated with significant capital additions. Approximately
$1,403,000, $458,000 and $120,000 of interest was capitalized for the years
ended December 31, 1998, 1997 and 1996, respectively. Depreciation is provided
using the straight-line method over estimated useful lives ranging from three
to fifteen years.
 
During 1998, the Company completed the allocation of the purchase prices
related to certain 1997 acquisitions and accordingly, reclassified
approximately $108.2 million of unallocated purchase price existing at
December 31, 1997 to goodwill and other intangible assets.
 
Goodwill and Other Intangible Assets--Goodwill and other intangible assets
represents principally the excess of purchase price over the estimated fair
value of net assets acquired, and the value of existing site rental customer
contracts, deferred financing costs, deferred acquisition costs and non-
competition agreements. Goodwill and site rental customer contracts are being
amortized over an estimated aggregate useful life of fifteen years using the
straight-line method. The consolidated financial statements reflect the
preliminary allocation of certain purchase prices as the appraisals for some
acquisitions have not yet been finalized. The portion of intangible assets
relating to deferred financing costs and a non-competition agreement are being
amortized on a straight-line basis over their estimated useful lives, ranging
from five to eight years. (See Note 3).
 
Notes Receivable--In June 1998, ATC entered into an agreement to acquire a
company which is in the process of constructing towers in the Tampa, Florida
area. Subject to the satisfaction of certain conditions, including, depending
on the circumstances, the expiration or earlier termination of the Hart-Scott
Rodino (HSR Act) waiting period, the acquisition is expected to be consummated
in the Spring of 1999. Prior to the acquisition's closing, ATC has agreed to
advance construction funds to the seller in an aggregate amount not to exceed
$12.0 million in the form of a secured note (guaranteed by the stockholders
and secured by the stock of the seller), of which approximately $7.1 million
was advanced through December 31, 1998. The secured note would be payable in
the event the acquisition was not consummated.
 
In connection with the acquisition of Wauka Communications and Grid Site
Services, Inc. described in Note 9, the Company assumed certain notes
receivable. The notes bear interest at 9% and the outstanding balance was
approximately $485,000 as of December 31, 1998.
 
In connection with the acquisition of OPM-USA-INC. (OPM) and the acquisition
of Gearon & Co. Inc. (Gearon) described in Note 9, the Company entered into
certain note agreements prior to consummation of these acquisitions. The
Company agreed to advance OPM an amount not to exceed $37.0 million, of which
approximately $5.7 million (excluding accrued interest) was advanced as of
December 31, 1997. The note bore interest at the prime rate plus 3%, was
unsecured and was settled upon closing of the OPM acquisition. In addition,
the Company also advanced Gearon $10.0 million of unsecured notes receivable,
which bore interest at a rate of approximately 7.25%. Such notes and accrued
interest thereon were settled upon the closing in January of 1998.
 
Income Taxes--Deferred taxes are provided to reflect temporary differences in
basis between book and tax assets and liabilities measured using currently
enacted tax rates. Through January 1998, the Company participated in a
 
                                      F-9
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)
 
tax sharing agreement with ARS. The tax sharing agreement was terminated in
connection with the corporate restructuring described above; the Company and
its subsidiaries now prepare and file income tax returns on a separate
consolidated basis. (See Note 7).
 
Loss Per Common Share--Basic and diluted income or loss per common share have
been determined in accordance with Statement of Financial Accounting Standards
(FAS) No. 128, "Earnings Per Share" whereby basic income or loss per common
share is computed by dividing net income or loss by the weighted average
number of common shares outstanding during the period. Diluted per share
amounts are computed by adjusting the weighted average number of common shares
and for dilutive potential common shares outstanding during the period, if
any. In computing diluted per share amounts, the Company uses the treasury
stock method, whereby unexercised options are assumed to be exercised at the
beginning of the period or at issuance, if later. The assumed proceeds are
then used to purchase common shares at the average market price during the
period. Shares outstanding upon the consummation of the ATC Separation are
assumed to be outstanding for all of 1997 and 1996 and prior to June 4, 1998.
Shares issuable upon exercise of options have been excluded from the
computation of diluted loss per common share as the effect is anti-dilutive.
Had options been included in the computation, shares for the diluted
computation would have increased by approximately 3.9 million in 1998.
Subsequent to December 31, 1998, ATC issued additional shares of common stock
and assumed certain options in connection with the transactions described in
Note 12.
 
Tower Separation Expenses--Tower separation expenses consist of costs incurred
in connection with the separation of the Company from its Former Parent and
include legal, accounting, financial advisory, and consent solicitation fees.
The Company may incur additional separation expenses through the resolution of
the ATC Separation adjustments described above, but does not expect such costs
to be material to the Company's consolidated results of operations, liquidity
or financial position.
 
Impairment of Long-Lived Assets--Recoverability of long-lived assets is
determined by periodically comparing the forecasted undiscounted net cash
flows of the operations to which the assets relate to the carrying amount,
including associated intangible assets of such operations. Through December
31, 1998, no impairments requiring adjustment have occurred.
 
Stock-Based Compensation--Compensation related to equity grants or awards to
employees is measured using the intrinsic value method prescribed by
Accounting Principles Board Opinion No. 25 "Accounting For Stock Issued To
Employees." In addition, the Company provides the required disclosures under
FAS No. 123, "Accounting For Stock Based Compensation" as if the fair-value
based method (defined in FAS No. 123) had been applied. (See Note 8).
 
Fair Value of Financial Instruments--The Company believes that the carrying
value of all financial instruments, excluding the interest rate protection
agreements, is a reasonable estimate of fair value as of December 31, 1998 and
1997. The fair value of the interest rate protection agreements are obtained
from independent market quotes. These values represent the amount the Company
would receive or pay to terminate the agreements taking into consideration
current market interest rates. The Company would expect to pay approximately
$369,000 and $97,000 to settle these agreements at December 31, 1998 and 1997,
respectively. (See Note 4).
 
Retirement Plans--The Company has a 401(k) plan covering substantially all
employees, subject to certain minimum age and length of employment
requirements. Under the plan, the Company matches 30% of participants'
contributions up to 5% of compensation. Prior to the ATC Separation, employees
of ATC participated in a similar plan sponsored by ARS. ATC contributed
approximately $207,700, $16,800 and $6,000 to the plans for the years ended
December 31, 1998, 1997 and 1996, respectively.
 
                                     F-10
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)
 
 
Recent Accounting Pronouncements--Effective January 1, 1998, the Company
adopted the provisions of FAS No. 130, "Reporting Comprehensive Income." There
are currently no items other than net loss which would be classified as part
of comprehensive income.
 
In June 1997, the Financial Accounting Standards Board (FASB) released FAS No.
131 "Disclosures about Segments of an Enterprise and Related Information,"
which ATC adopted in 1998. (See Note 11).
 
In February 1998, the FASB released FAS No. 132, "Employer's Disclosures about
Pensions and other Post- retirement Benefits," which ATC adopted in 1998. The
adoption had no impact on the Company's results of consolidated operations,
liquidity or financial position.
 
In June 1998, the FASB issued FAS No. 133, "Accounting for Derivative
Instruments and Hedging Activities." This statement is effective for all
fiscal quarters of years beginning after June 15, 1999. The Company is in the
process of completing its evaluations of FAS No. 133.
 
Reclassifications--Certain reclassifications have been made to the 1996 and
1997 financial statements to conform with the 1998 presentation.
 
2. PROPERTY AND EQUIPMENT
 
  Property and equipment consist of the following as of December 31 (in
thousands):
 
<TABLE>
<CAPTION>
                                                             1998      1997
                                                           --------  --------
   <S>                                                     <C>       <C>
   Land and improvements.................................. $ 38,242  $ 17,956
   Buildings and improvements.............................   59,447    17,732
   Towers.................................................  289,334    48,316
   Technical equipment....................................    9,381     3,624
   Transmitter equipment..................................   29,290    18,212
   Office equipment, furniture, fixtures and other
    equipment.............................................   14,863     4,076
   Construction in progress...............................   31,926    10,642
                                                           --------  --------
       Total..............................................  472,483   120,558
   Less accumulated depreciation and amortization.........  (23,007)   (2,940)
                                                           --------  --------
   Property and equipment, net............................ $449,476  $117,618
                                                           ========  ========
 
3. GOODWILL AND OTHER INTANGIBLE ASSETS
 
  The Company's intangible assets consist of the following as of December 31
(in thousands):
 
<CAPTION>
                                                             1998      1997
                                                           --------  --------
   <S>                                                     <C>       <C>
   Goodwill and site rental customer contracts............ $739,933  $111,918
   Deferred financing costs...............................    8,891     2,519
   Non-compete agreements.................................    6,018     5,530
   Deferred acquisition costs.............................    2,513       438
   Other..................................................                647
                                                           --------  --------
      Total...............................................  757,355   121,052
   Less accumulated amortization..........................  (38,780)   (4,436)
                                                           --------  --------
   Other intangible assets, net........................... $718,575  $116,616
                                                           ========  ========
</TABLE>
 
                                     F-11
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)
 
 
4. FINANCING ARRANGEMENTS
 
Outstanding amounts under the Company's long-term financing arrangements
consisted of the following as of December 31 (in thousands):
<TABLE>
<CAPTION>
                                                                1998     1997
                                                              --------  -------
   <S>                                                        <C>       <C>
   Credit Facilities......................................... $275,000  $88,500
   Notes payable.............................................    5,854    1,466
   Other obligations.........................................      275      210
                                                              --------  -------
   Total.....................................................  281,129   90,176
   Less current portion......................................   (1,652)    (110)
                                                              --------  -------
   Long-term debt............................................ $279,477  $90,066
                                                              ========  =======
</TABLE>
 
Credit Facilities--Through June 16, 1998 the Borrower Subsidiaries were party
to a loan agreement which provided a $250.0 million loan commitment, with an
additional amount of $150.0 million available at the discretion of the
Borrower Subsidiaries. In June 1998, ATC and the Borrower Subsidiaries entered
into new loan agreements (the Credit Facilities) which provide for total
available credit of $925.0 million as of December 31, 1998. The Credit
Facilities consist of a term loan to ATC for $150.0 million, revolving credit
facilities to the Borrower Subsidiaries totaling $650.0 million, and a term
loan to the Borrower Subsidiaries of $125.0 million. Interest on the Credit
Facilities is payable in accordance with the applicable term of the London
Interbank Offering Rate (LIBOR) agreement or quarterly, and accrues, at ATC's
option, either at the LIBOR plus margin (as defined) or the Base Rate plus
applicable margin (as defined). The interest rate in effect at December 31,
1998 for the ATC term loan and the Borrower Subsidiaries term loan and
revolving credit facilities was 8.71% and 7.30%, respectively. For the years
ended December 31, 1998, 1997 and 1996, the weighted average interest rate of
the Company's various credit facility agreements was 7.7%, 7.4% and 8.75%,
respectively.
 
The ATC term loan is due in quarterly installments, commencing June 30, 2001
in amounts equal to 0.25% of the outstanding principal on such quarter ended
through June 30, 2006, with the remaining balance due in equal installments on
September 30, and December 31, 2006. The Borrower Subsidiaries' revolving
credit facility and term loan are due in quarterly installments, commencing
June 30, 2001 in amounts varying from 2.5% to 11.25% of outstanding principal,
with ultimate maturity on June 30, 2006.
 
Borrowings under the Credit Facilities are conditioned upon the Company's
compliance with defined borrowing formulas, which at December 31, 1998 permit
borrowing availability of an additional $100 million. The Credit Facilities
also require maintenance of various financial covenants and ratios, none of
which the Company believes are restrictive to its present or planned business
activities. The loans to ATC and the Borrower Subsidiaries are cross-
guaranteed and cross-collateralized by substantially all of the assets of ATC.
 
The Borrower Subsidiaries are required to pay quarterly commitment fees
depending on their consolidated financial leverage, on the aggregate unused
portion of the aggregate commitment. Commitment fees paid related to the
Company's various credit facility agreements aggregated approximately
$1,172,000, and $416,000 and $24,000 for the years ended December 31, 1998,
1997 and 1996, respectively.
 
In connection with the repayment of existing borrowings with proceeds of
borrowings under the Credit Facilities, ATC recognized an extraordinary loss
of approximately $1.4 million, net of a tax benefit of $0.9 million during the
second quarter of 1998. Following the October 1997 closing of the credit
facility, ATC incurred an extraordinary loss of approximately $0.7 million,
net of a tax benefit of $0.5 million. The Company also incurred an
extraordinary loss in connection with the ATC Preferred Stock Financing. (See
Note 8).
 
Derivative Positions--Under the terms of the Credit Facilities, the Company is
required, under certain conditions, to enter into interest rate protection
agreements. ATC's exposure under these agreements is limited
 
                                     F-12
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)
 
to the impact of variable interest rate fluctuations and the periodic
settlement of amounts due under these agreements if the other parties fail to
perform.
 
The following interest rate protection agreements were held as of December 31,
1998 (in thousands, except percentages):
 
 
<TABLE>
<CAPTION>
                                                  Expiration
   Description                   Notional Amount     Dates     Interest Rate
   -----------                   --------------- ------------- -------------
   <S>                           <C>             <C>           <C>
   Interest rate cap agreement       $ 7,000(1)  November 1999     8.5%
   Interest rate cap agreement        21,500     January 2000      8.5%
   Interest rate cap agreement        23,750     April 2000        8.5%
   Interest rate cap agreement        21,610(1)  July 2000         9.5%
   Interest rate swap agreement        7,340(1)  January 2001      6.4%
   Interest rate swap agreement       17,550     June 2003         5.9%
                                     -------
   Total                             $98,750
                                     =======
</TABLE>
- --------
(1) Interest rate protection agreement also held as of December 31, 1997.
 
Notes Payable--A limited liability company, which is under majority control of
the Company, has a note secured by the minority shareholder's interest in the
limited liability company. Interest rates under this note are determined, at
the option of the limited liability company, at either the Floating Rate (as
defined in the note agreement) or the Federal Home Loan BankBoston rate plus
2.25%. As of December 31, 1998 and 1997, the effective interest rate on
borrowings under this note was 8.02%. The note is payable in equal monthly
principal payments with interest through 2006.
 
In connection with the ATC Merger discussed in Note 9, the Company assumed
certain long-term note obligations of the acquired entity including a term
note payable that was paid at closing, a $4.4 million noninterest-bearing
secured note payable, due in annual installments through December 2000 and a
$430,000 noninterest-bearing unsecured note payable, maturing in October 1999.
 
In connection with the Wauka Communications, Inc. and Grid Site Services, Inc.
acquisitions described in Note 9, the Company assumed certain long-term note
obligations of the acquired entities including term notes payable that were
paid at closing, and a $544,000, 12% note payable, due in monthly installments
through July 2005.
 
Other Obligations--In connection with various acquisitions, the Company
assumed certain long-term obligations of the acquired entities. Substantially
all of these obligations were repaid during 1997, with the remaining unpaid
obligation payable in monthly installments through 2014.
 
Future principal payments required under the Company's financing arrangements
at December 31, 1998 are approximately as follows (in thousands):
 
<TABLE>
   <S>                                                                  <C>
   Year Ending:
   1999................................................................ $  1,652
   2000................................................................    2,698
   2001................................................................   10,723
   2002................................................................   17,361
   2003................................................................   20,507
   Thereafter..........................................................  228,188
                                                                        --------
     Total............................................................. $281,129
                                                                        ========
</TABLE>
 
                                     F-13
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)
 
5. COMMITMENTS AND CONTINGENCIES
 
Lease Obligations--The Company leases land and office, tower and satellite
space under operating leases that expire over various terms. Many of the
leases also contain renewal options with specified increases in lease payments
upon exercise of the renewal option.
 
Future minimum rental payments under noncancelable operating leases in effect
at December 31, 1998 are approximately as follows (in thousands):
 
<TABLE>
   <S>                                                                   <C>
   Year Ending:
   1999................................................................. $11,646
   2000.................................................................  11,810
   2001.................................................................  10,622
   2002.................................................................   8,188
   2003.................................................................   5,828
   Thereafter...........................................................  40,076
                                                                         -------
     Total.............................................................. $88,170
                                                                         =======
</TABLE>
 
Aggregate rent expense under operating leases for the years ended December 31,
1998, 1997 and 1996 approximated $10,818,000, $2,110,000 and $420,000,
respectively.
 
Customer Leases--The Company's lease agreements with its customers, vary
depending upon the industry user. Leases with television and radio
broadcasters are typically long-term leases (generally from 15 to 20 years),
while leases to wireless communications providers typically have shorter lease
terms (generally from five to ten years), with multiple renewals at the option
of the tenant. The leases acquired in the ATC merger (see Note 9) tend to be
of shorter duration, generally two years, and permit earlier termination if
ATC were to attempt to impose price increases relating to escalator
provisions. Leases of all lengths are generally renewed by the lessees due to
the costs and disruption associated with reconfiguring a wireless network or
broadcast location.
 
Most leases have escalator provisions (annual automatic increases based on
specified estimated cost measures or on increases in the consumer price
index). ATC also subleases space on communications towers under the same terms
and conditions, including cancellation rights, as those found in its own lease
contracts.
 
Future minimum rental receipts expected to be received from customers under
noncancelable operating lease agreements in effect at December 31, 1998 are
approximately as follows (in thousands):
 
<TABLE>
   <S>                                                                  <C>
   Year Ending:
   1999................................................................ $ 57,214
   2000................................................................   52,459
   2001................................................................   47,739
   2002................................................................   37,491
   2003................................................................   22,494
   Thereafter..........................................................   84,323
                                                                        --------
     Total............................................................. $301,720
                                                                        ========
</TABLE>
 
Tower rental revenues under the Company's sub-leases approximated $1,072,000,
$978,000 and $468,000 for the years ended December 31, 1998, 1997 and 1996,
respectively.
 
Acquisition Commitments--See Notes 9 and 12 for information with respect to
acquisitions and related commitments.
 
                                     F-14
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)
 
 
ATC Separation--See Note 1 for the details of the ATC Separation Agreement.
 
Litigation--The Company periodically becomes involved in various claims and
lawsuits that are incidental to its business. In the opinion of management,
after consultation with counsel, there are no matters currently pending which
would, in the event of adverse outcome, have a material impact on the
Company's consolidated financial position, the results of operations or
liquidity.
 
6. RELATED PARTY TRANSACTIONS
 
During the period that the Company was a majority owned subsidiary of ARS, the
Company received revenues of approximately $565,000, $389,000 and $70,000 from
ARS for tower rentals at Company-owned sites for the period ending June 4,
1998 (date of ATC Separation) and years ended December 31, 1997 and 1996,
respectively.
 
In January 1998, ARS contributed to ATC 19 communications sites used by ARS
and various third parties (with an ARS aggregate net book value of
approximately $4.7 million), and ARS and ATC entered into leases or subleases
of space on the transferred towers. In May 1998, two additional communications
sites were transferred and leases were entered into following acquisition by
ARS of the sites from third parties. These sites were contributed to ATC at an
aggregate ARS net book value of approximately $0.3 million.
 
In June 1998, ARS contributed the majority of its corporate fixed assets to
ATC (with an ARS net book value of approximately $1.4 million).
 
Chase Manhattan Bank (Chase), an affiliate of Chase Equity Associates (CEA)
and stockholder of the Company, was a lender with a 6.75% participation under
the loan agreement entered into by ATI and has a 5.2% participation under the
Credit Facilities for the Borrower Subsidiaries. Chase is an affiliate of
Chase Capital Partners ("CCP"), the general partner of CEA; a director of ATC
and formerly a director of (ARS), is a general partner of CCP. At December 31,
1998, the aggregate principal amount outstanding under the Credit Facilities
was approximately $275.0 million. CEA's share of interest and fees paid by ATC
pursuant to its various credit arrangements was $0.8 million and $0.2 million
in 1998 and 1997.
 
In January 1998, the Company consummated the transactions contemplated by a
stock purchase agreement with certain related parties. (See Note 8).
 
In August 1998, an executive officer of the Company received a $1,022,366
demand loan. In December 1998, the officer repaid $700,000 and such interest
bearing loan remained outstanding in the principal amount of approximately
$322,000 as of December 31, 1998.
 
                                     F-15
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)
 
 
7. INCOME TAXES
 
The income tax benefit (provision) from continuing operations was comprised of
the following for the years ended December 31 (in thousands):
 
<TABLE>
<CAPTION>
                                                         1998     1997   1996
                                                       ---------  -----  ----
   <S>                                                 <C>        <C>    <C>
   Current:
     Federal.......................................... $(116,322) $ 444  $ 54
     State............................................   (18,866)   175    10
   Deferred:
     Federal..........................................    (8,407)  (125)  (93)
     State............................................      (841)   (21)  (16)
   Less:
     Deferred tax assets related to corporate tax
      restructuring
      (see Note 1)....................................   150,150
     Benefit from disposition of stock options
      recorded to additional paid-in capital..........    (1,223)
                                                       ---------  -----  ----
   Income tax benefit (provision)..................... $   4,491  $ 473  $(45)
                                                       =========  =====  ====
</TABLE>
 
A reconciliation between the U.S. statutory rate from continuing operations
and the effective rate was as follows for the years ended December 31:
 
<TABLE>
<CAPTION>
                                                              1998  1997  1996
                                                              ----  ----  ----
   <S>                                                        <C>   <C>   <C>
   Statutory tax rate........................................  35%   34%   34 %
   State taxes, net of federal benefit.......................   4     6     6
   Non-deductible tower separation expenses ................. (11)
   Nondeductible goodwill and intangible amortization........ (16)  (17)  (49)
   Other.....................................................  (1)         (1)
                                                              ---   ---   ---
   Effective tax rate........................................  11%   23%  (10)%
                                                              ===   ===   ===
</TABLE>
 
Significant components of the Company's deferred tax assets and liabilities
were composed of the following as of December 31 (in thousands):
 
<TABLE>
<CAPTION>
                                                                 1998    1997
                                                               --------  -----
<S>                                                            <C>       <C>
Current assets:
  Allowances and accruals made for financial reporting
   purposes which are currently nondeductible................. $    495  $  63
                                                               --------  -----
      Total current assets.................................... $    495  $  63
                                                               ========  =====
Long-term items:
  Assets:
    Tax basis step-up from corporate tax restructuring and tax
     planning strategies...................................... $142,642
    Net operating loss carry-forwards.........................   25,477
  Liabilities:
    Property and equipment and intangible assets, principally
     due to
     amortization methods.....................................  (58,701) $(418)
                                                               --------  -----
  Net long-term deferred tax assets (liabilities)............. $109,418  $(418)
                                                               ========  =====
</TABLE>
 
 
                                     F-16
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)
 
At December 31, 1998, the Company has net operating loss carry-forwards
available to reduce future taxable income of $66,173,000 for federal and state
purposes. These loss carry-forwards expire through 2013. In the opinion of
management, deferred tax assets are more likely than not recoverable,
therefore a valuation allowance has not been provided in the accompanying
consolidated financial statements as of December 31, 1998 and 1997.
 
8. STOCKHOLDERS' EQUITY
 
July Offering--On July 8, 1998, the Company completed a public offering of
27,861,987 shares of Class A common stock, $.01 par value per share (including
2,361,987 shares sold by the Company pursuant to the exercise in full of the
underwriters' over-allotment option) at $23.50 per share. Certain selling
stockholders sold an additional 3,874,911 shares in the offering. The
Company's net proceeds of the offering (after deduction of the underwriting
discount and estimated offering expenses) were approximately $625.0 million.
On July 9, 1998, the Company used approximately $306.1 million of the net
proceeds from the offering to redeem all of the outstanding shares of the
Interim Preferred Stock described below. The balance was invested in short-
term investment grade securities and will be used, together with borrowings
under the Credit Facilities, to fund future acquisitions and construction
activities.
 
ATC Preferred Stock Financing--On June 4, 1998, the Company entered into a
stock purchase agreement (the Interim Financing Agreement) with respect to a
preferred stock financing which provided for the issuance and sale by ATC of
up to $400.0 million of Series A Redeemable Pay-In-Kind Preferred Stock (the
Interim Preferred Stock) to finance ATC's obligation to CBS with respect to
tax reimbursement. The Company issued $300.0 million of Interim Preferred
Stock, which accrued dividends at a rate equal to the three-month LIBOR then
in effect (approximately 5.69%) plus an agreed upon adjustable spread (5.0%
for the period in which the obligation was outstanding). Due to the short term
nature of the issue, accrued dividends were recorded as interest expense in
the accompanying consolidated financial statements. Such interest expense
approximated $3.1 million for the year ended December 31, 1998. The Interim
Preferred Stock was redeemed on July 9, 1998 at a redemption price equal to
$1,010 per share plus accrued and unpaid dividends for an aggregate redemption
value of $306.1 million. The Company incurred an extraordinary loss of
approximately $7.5 million, net of a tax benefit of $5.0 million, during the
third quarter of 1998, representing the write-off of certain commitment,
deferred financing and redemption fees.
 
ATC Stock Purchase Agreement--On January 22, 1998, the Company consummated the
transactions contemplated by the stock purchase agreement (the ATC Stock
Purchase Agreement), dated as of January 8, 1998, with Steven B. Dodge,
Chairman of the Board, President and Chief Executive Officer of ARS and ATC,
and certain other officers and directors of ARS (or their affiliates or family
members or family trusts), pursuant to which those persons purchased
8.0 million shares of ATC common stock at a purchase price of $10.00 per share
for an aggregate purchase price of approximately $80.0 million, including 4.0
million shares by Mr. Dodge for $40.0 million. Payment of the purchase price
was in the form of cash aggregating approximately $30.6 million and in the
form of notes aggregating approximately $49.4 million which were repaid upon
the consummation of the ATC Separation.
 
Voting Rights--The Class A and B common stock entitles the holder to one and
ten votes, respectively, per share. The Class C common stock is non-voting.
 
Recapitalization--In November 1997, the Company effected a recapitalization,
pursuant to which each share of the Company's existing common stock was
cancelled and the Company was recapitalized with 29,667,883 shares of Class A
common stock, 4,670,626 shares of Class B common stock and 1,295,518 shares of
Class C common stock.
 
Stock Option Plans--Effective November 5, 1997, ATC instituted the 1997 Stock
Option Plan, as amended and restated on April 27, 1998 (the Plan), which is
administered by the Compensation Committee of the ATC Board.
 
                                     F-17
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)
 
The option pool under the Plan consists of an aggregate of 15,000,000 shares
of common stock that may consist of shares of Class A common stock, shares of
Class B common stock or some combination thereof. The Plan was amended in June
1998 to provide that all future grants of options under the Plan must be to
purchase shares of Class A common stock. The Plan includes options that were
converted from the stock option plan of ATI. In July 1996, ATI adopted a stock
option plan and, pursuant thereto, options were granted to various officers of
ATI. In connection with the ATC Separation, those options to purchase the
common stock of ATI were converted into options to acquire shares of Class A
common stock under the Plan. The Company has reserved 18,140,316 shares of
common stock for issuance under the Plan and the circumstances discussed
below.
 
In addition to the 15,000,000 shares authorized under the Plan, options to
purchase an aggregate of 2,168,466 shares of Class A common stock and Class B
common stock were outstanding as of December 31, 1998 outside of the Plan.
These options are the result of the exchange of certain ARS options that
occurred pursuant to the ATC Separation and assumption of certain options that
occurred pursuant to the ATC Merger described in Note 9. Each unexercised
option to purchase shares of ARS common stock held by persons who became
directors or employees of ATC were exchanged for ATC options. The ARS options
were exchanged in a manner that preserved the spread in such ARS options
between the option exercise price and the fair market value of ARS common
stock and the ratio of the spread to the exercise price prior to such
conversion. In connection with the OmniAmerica Merger described in Note 12,
ATC assumed approximately 1.0 million Omni options that are not included in
the Plan.
 
Exercise prices in the case of incentive stock options are not less than the
fair value of the underlying common stock on the date of grant. Exercise
prices in the case of non-qualified stock options are set at the discretion of
the Company's Board of Directors. Options vest ratably over various periods,
generally five years, commencing one year from the date of grant. There have
been no option grants at exercise prices less than fair value.
 
The following table summarizes the Company's option activity for the periods
presented:
 
<TABLE>
<CAPTION>
                                                                       Weighted
                                        Weighted Average               Average
                                            Exercise       Options    Remaining
                           Options           Price       Exercisable Life (Years)
                          ----------    ---------------- ----------- ------------
<S>                       <C>           <C>              <C>         <C>
Granted during 1996 and
 outstanding at December
 31, 1996...............     550,000            $ 5.00      160,000      8.71
Granted.................     172,000      $7.50-$ 8.00                   9.24
Cancelled...............     (40,000)           $ 5.00
                          ----------      ------------    ---------      ----
Outstanding as of Decem-
 ber 31, 1997...........     682,000(a)         $ 5.68      160,000      8.89
                          ==========      ============    =========      ====
Options converted from
 ATI to ATC Plan........     931,332(a)         $ 4.16      252,640      7.88
Options transferred from
 American Radio.........   1,862,806            $ 6.21      723,660      7.06
Options transferred in
 connection with ATC
 Merger (See Note 9)....   1,252,364            $ 2.29      537,339      8.00
                          ----------      ------------    ---------      ----
Subtotal................   4,046,502            $ 4.53    1,513,639      7.44
                          ----------      ------------    ---------      ----
Granted.................   8,371,700            $16.16
Exercised...............  (1,103,213)           $ 2.48
Cancellations...........    (226,894)           $ 8.80
                          ----------      ------------    ---------      ----
Outstanding as of
 December 31, 1998......  11,088,095            $13.43    1,513,639      8.85
                          ==========      ============    =========      ====
  (a) ATI options
      outstanding as of
      December 31, 1997
      were converted to
      931,332 ATC
      options.
</TABLE>
 
 
                                     F-18
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)
 
The following table sets forth information regarding options outstanding at
December 31, 1998:
 
<TABLE>
<CAPTION>
 Outstanding                                                         Weighted Average
  Number of     Options   Range of Exercise     Weighted Average      Remaining Life
   Options    Exercisable  Price Per Share  Exercise Price Per Share     (Years)
 -----------  ----------- ----------------- ------------------------ ----------------
  2,424,420    1,432,301    $ 2.05-$ 8.77            $ 4.65                7.34
 <S>          <C>         <C>               <C>                      <C>
    411,838       81,338    $ 9.09-$ 9.09            $ 9.09                8.01
  2,847,803                 $10.00-$10.00            $10.00                9.01
  1,737,934                 $13.00-$19.75            $13.94                9.22
  3,666,100                 $21.13-$26.50            $22.13                9.65
 ----------    ---------    -------------            ------                ----
 11,088,095    1,513,639    $ 2.05-$26.50            $13.43                8.85
 ==========    =========    =============            ======                ====
</TABLE>
 
Pro Forma Disclosure--As described in Note 1, the Company uses the intrinsic
value method to measure compensation expense associated with grants of stock
options or awards to employees. Accordingly, there is no compensation cost
related to option grants reflected in the accompanying consolidated financial
statements. Had the Company used the fair value method to measure compensation
for grants under all plans made in 1998, 1997 and 1996, the reported net loss
and basic and diluted loss per common share would have been as follows (in
thousands, except per share amounts):
 
<TABLE>
<CAPTION>
                                                         1998     1997    1996
                                                       --------  -------  -----
   <S>                                                 <C>       <C>      <C>
   Net loss........................................... $(62,439) $(2,492) $(568)
   Basic and diluted earnings per share...............   $(0.78)  $(0.05) $(.01)
</TABLE>
 
 
The "fair value" of each option grant is estimated on the date of grant using
the Black/Scholes option pricing model. Key assumptions used to apply this
pricing model are as follows:
 
<TABLE>
<CAPTION>
                                                           1998    1996 and 1997
                                                          -------  -------------
   <S>                                                    <C>      <C>
   Approximate risk-free interest rate...................    5.5%     6.3%
   Expected life of option grants........................ 5 years     5 years
   Expected volatility of underlying stock...............   177.5%    N/A
   Expected dividends....................................     N/A     N/A
</TABLE>
 
9. ACQUISITIONS
 
General--The acquisitions consummated during 1998 and 1997 have been accounted
for by the purchase method of accounting. The purchase prices have been
allocated to the net assets acquired, principally intangible and tangible
assets, and the liabilities assumed based on their estimated fair values at
the date of acquisition. The excess of purchase price over the estimated fair
value of the net assets acquired has been recorded as goodwill and other
intangible assets. For certain acquisitions the financial statements reflect
the preliminary allocation of purchase prices as the appraisals of the assets
acquired have not been finalized. The Company does not expect any changes in
depreciation and amortization as a result of such appraisals to be material to
the consolidated results of operations.
 
1998 Acquisitions--During the year ended December 31, 1998, the Company
acquired various communications sites and a major site acquisition business
for an aggregate preliminary purchase price of approximately $853.8 million,
including the issuance of approximately 36.3 million shares of Class A common
stock valued at approximately $382.6 million. The following describes the more
significant acquisitions:
 
                                     F-19
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)
 
In January 1998, the Company acquired all of the outstanding stock of Gearon &
Co. Inc. (Gearon), a company based in Atlanta, Georgia, for an aggregate
purchase price of approximately $80.0 million. The purchase price consisted on
approximately $32.0 million in cash, assumed liabilities and the issuance of
approximately 5.3 million shares of Class A common stock at a price of $9.00
per share. Gearon is engaged in site acquisition, development, construction
and facility management of wireless network communication facilities.
 
In January 1998, ATC acquired all the outstanding stock of OPM-USA-INC. (OPM),
a company that owned and developed communications towers, and owned
approximately 90 towers at the time of acquisition (the OPM Transaction). The
initial purchase price was variable based on the number of towers developed
for ATC and the forward looking cash flow of such towers. Subsequently, in
December 1998, the purchase price was fixed at $70.0 million excluding the
assumption of certain liabilities. The final price included a total of more
than 150 towers and a right of first refusal granted to American Tower with
respect to, any towers that the former owner of OPM develops. The final
payment due to OPM of approximately $21.9 million is recorded as accrued
acquisition purchase price in the accompanying consolidated financial
statements.
 
In May 1998, the Company consummated the acquisition of the assets relating to
the teleport business serving the Washington D.C. area for approximately $30.5
million.
 
On June 8, 1998, the Company consummated the American Tower Corporation Merger
(ATC Merger) pursuant to which that entity was merged into ATC. The
preliminary purchase price was approximately $470.0 million. At the time of
closing, the acquired company owned approximately 775 communications towers
and managed approximately 125 communications towers. In conjunction with the
ATC Merger, the Company issued 28,782,386 shares of Class A common stock
valued at approximately $287.8 million (excluding 1,252,364 shares of common
stock reserved for options held by former employees of the acquired company
valued at approximately $9.7 million) and assumed approximately $4.5 million
of redeemable preferred stock (which was paid at closing) and $122.7 million
of debt (of which approximately $118.3 million, including interest and
associated fees, was paid at closing). The purchase price also includes
acquisition costs, assumed working capital and deferred income taxes. The
Company borrowed $57.0 million under the then existing credit agreements to
fund a portion of the debt pay-off. Upon consummation of the ATC Merger, the
Company changed its name from American Tower Systems Corporation to American
Tower Corporation.
 
In June 1998, the Company merged with a company owning a broadcasting tower in
the Boston, Massachusetts area and issued 720,000 shares of Class A common
stock valued at approximately $18.0 million to close the transaction. In
addition, under a put agreement that was consummated in connection with the
merger, the sellers have the right to require the Company to purchase, at any
time prior to June 5, 1999, any or all shares of Class A common stock received
pursuant to consummation of the merger for a purchase price equal to the then
current market price. In connection with the public offering described in Note
8, the sellers sold 383,750 of the 720,000 shares in July 1998 reducing the
Company's overall redemption obligation. Accordingly, the remaining 336,250
shares have been recorded as redeemable Class A common stock in the
accompanying consolidated financial statements based on the December 31, 1998
fair market value of $29.5625 per share.
 
In October 1998, the Company acquired approximately 300 towers and certain
tower related assets in six transactions for an aggregate purchase price of
approximately $100.2 million. The most significant transactions included the
acquisition of 166 Atlanta, Georgia area towers. These transactions included
the acquisition of all the outstanding stock of Wauka Communications, Inc. and
the assets of Grid Site Services, Inc. The consideration in these related
transactions included the issuance of 1,430,881 shares of Class A common
stock, subject to certain escrow adjustments. Included in the total 300 towers
referenced above, the Company also required 137 communications sites and tower
related assets in the four other transactions.
 
                                     F-20
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)
 
 
In October 1998, the Company contributed cash and a tower aggregating $12.6
million to ATS-Needham LLC, (ATS Needham), a limited liability company in
which ATC owned a 50.1% interest prior to such transactions. ATS Needham also
sold certain assets to the minority interest party. As a result of these
transactions, ATC now owns an 80% interest in ATS Needham.
 
1997 Acquisitions--During the year ended December 31, 1997, ATC acquired
various communications sites, the assets of several affiliated site
acquisition businesses, and two tower site management businesses located in
southern California and South Carolina for an aggregate purchase price of
approximately $180.4 million. The following describes the most significant
acquisitions:
 
In October 1997, the Company acquired two affiliated entities operating
approximately 110 tower sites and a tower site management business located
principally in northern California for approximately $45.0 million.
 
In October 1997, the Company acquired 128 tower sites and certain video,
voice, data and Internet transport operations for approximately $70.25
million.
 
In July 1997, the Company acquired the assets of three affiliated entities
which owned and operated approximately fifty towers and a tower site
management business in southern California for an aggregate purchase price of
approximately $33.5 million.
 
In May 1997, the Company acquired the assets of two affiliated companies
engaged in the site acquisition business in various locations in the United
States for approximately $13.0 million.
 
In May 1997, the Company and an unaffiliated party formed a limited liability
company to own and operate communication towers which will be constructed on
over 50 tower sites in northern California. The Company advanced approximately
$0.8 million to this entity and currently owns a 70% interest in the entity,
with the remaining 30% owned by an unaffiliated party. The accounts of the
limited liability company are included in the consolidated financial
statements with the other party's investment reflected as minority interest in
subsidiary.
 
Unaudited Pro Forma Operating Results--The operating results of these
acquisitions have been included in the Company's consolidated results of
operations from the date of acquisition. The following unaudited pro forma
summary presents the consolidated results of operations as if the acquisitions
had occurred as of January 1, 1997 after giving effect to certain adjustments,
including depreciation and amortization of assets and interest expense on debt
incurred to fund the acquisitions. These unaudited pro forma results have been
prepared for comparative purposes only and do not purport to be indicative of
what would have occurred had the acquisitions been made as of January 1, 1997
or results which may occur in the future.
 
<TABLE>
<CAPTION>
                                                               1998      1997
                                                             --------  --------
   <S>                                                       <C>       <C>
                                                              (In thousands,
                                                                  except
                                                              per share data-
                                                                unaudited)
   Operating revenues....................................... $126,919  $116,288
   Loss before extraordinary losses.........................  (53,755)  (41,412)
   Net loss.................................................  (62,647)  (42,106)
   Basic and diluted loss per common share..................    (0.67)    (0.53)
</TABLE>
 
                                     F-21
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)
 
 
10. SUPPLEMENTAL CASH FLOW INFORMATION
 
Supplemental cash flow information and noncash investing and financing
activities are as follows (in thousands):
 
<TABLE>
<CAPTION>
                                                        1998    1997    1996
                                                      -------- ------  -------
<S>                                                   <C>      <C>     <C>
Supplemental cash flow information:
  Cash paid during the period for interest (including
   amounts capitalized).............................. $ 23,011 $2,398  $    91
  Cash paid during the period for income taxes
   (including amounts paid to CBS)...................  212,196    125
Noncash investing and financing activities:
  Property, equipment and other assets transferred
   from ARS..........................................    6,489     51   11,103
  Property and equipment transferred to ARS..........            (724)
  Land transferred to Parent.........................                   (1,100)
  Deferred financing costs paid by ARS...............                    1,255
  Investment in affiliate paid by ARS................                      325
  Issuance of common stock and assumption of options
   for acquisitions..................................  392,226
  Increase in deferred tax assets from corporate tax
   restructuring.....................................  150,150
  Increase in due to CBS Corporation from estimated
   remaining tax liabilities.........................    5,021
  Adjustment to equity for CBS tax liability.........   61,715
  Accrual for final payment for OPM merger...........   21,914
  Tax benefit from disposition of stock options
   recorded to additional paid in capital............    1,223
Details of acquisitions financed by ARS..............
  Purchase price of net assets acquired..............                   20,954
  Liabilities assumed................................                   (2,220)
  Stock issued by ARS................................                   (8,153)
                                                                       -------
  Cash paid by ARS...................................                   10,581
  Less: cash acquired................................                   (1,600)
                                                                       -------
  Net cash paid by ARS for acquisitions..............                  $ 8,981
                                                                       =======
</TABLE>
 
11. BUSINESS SEGMENTS
 
The Company operates in three business segments: tower rental and management
(TRM), Services, and video, voice, data and Internet transmission services
(VVDI). The TRM segment provides for leasing and subleasing of antennae sites
on multi-tenant towers for a diverse range of wireless communication
industries, including personal communication services, paging, cellular,
enhanced specialized mobile radio, specialized mobile radio and fixed
microwave, as well as radio and television broadcasters. The Services segment
offers a broad range of network development services, including network
design, site acquisition and construction, zoning and other regulatory
approvals, tower construction and antennae installation. The VVDI segment
offers transmission services in the New York City to Washington, D.C. corridor
and in Texas.
 
The accounting policies applied in compiling segment information below are
similar to those described in Note 1. In evaluating financial performance,
management focuses on operating profit (loss) excluding depreciation and
amortization and corporate general and administrative expenses. This measure
of operating profit (loss) is also before tower separation expenses, interest
income, interest expense, minority interest in net earnings (loss) of
subsidiaries, income taxes and extraordinary items.
 
                                     F-22
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)
 
 
The Company's reportable segments are strategic business units that offer
different services. They are managed separately because each segment requires
different resources and marketing strategies. All segments operate exclusively
in the United States. In addition, all reported segment revenues are generated
from external customers.
 
Summarized financial information concerning the Company's reportable segments
is shown in the following table. The "Other" column below represents amounts
excluded from specific segments such as income taxes corporate general and
administrative expenses, tower separation expenses, depreciation and
amortization and interest. In addition, other also includes corporate assets
such as cash and cash equivalents, tangible and intangible assets, and income
tax accounts which have not been allocated to specific segments (in
thousands).
 
<TABLE>
<CAPTION>
                                 TRM    Services  VVDI    Other      Total
                               -------- -------- ------- --------  ----------
<S>                            <C>      <C>      <C>     <C>       <C>
1998
Revenues...................... $ 60,505 $23,315  $19,724           $  103,544
Income (loss) before benefit
 (provision) for income taxes
 and extraordinary losses.....   31,050   3,836    6,907 $(84,234)    (42,441)
Assets........................  979,349  91,444   64,359  367,191   1,502,343
Capital expenditures..........  118,926      61    3,405    4,063     126,455
Depreciation and
 amortization.................   37,698   7,038    4,887    2,441      52,064
1997
Revenues...................... $13,302  $ 2,122  $ 2,084           $   17,508
Income (loss) before benefit
 (provision) for income taxes
 and extraordinary losses.....    7,222     762      811 $(10,844)     (2,049)
Assets........................  223,202  12,032   13,549    6,574     255,357
Capital expenditures..........   20,145      19       69      381      20,614
Depreciation and
 amortization.................    4,583   1,073      556      114       6,326
1996
Revenues...................... $  2,897                            $    2,897
Income (loss) before benefit
 (provision) for income taxes
 and extraordinary losses.....    1,455                  $ (1,889)       (434)
Assets........................   36,691                       426      37,117
Depreciation and
 amortization.................      990                                   990
</TABLE>
 
                                     F-23
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)
 
 
12. OTHER TRANSACTIONS
 
 Consummated Transactions:
 
February Offering: On February 9, 1999, American Tower completed a public
offering (the February Offering) of 25,700,000 shares of Class A common stock,
$.01 par value per share (including 1,700,000 shares sold by ATC pursuant to
the exercise in full of the underwriters' over-allotment option) at $25.00 per
share. Certain selling stockholders sold an additional 1,300,000 shares in the
offering. ATC's net proceeds of the offering (after deduction of the
underwriting discount and estimated offering expenses) were approximately
$619.3 million. ATC invested the proceeds in short-term investment grade
securities. ATC will continue to use such investments together with borrowings
under the Credit Facilities to fund acquisitions and construction activities.
 
February Private Placement: On February 9, 1999, American Tower consummated
the sale (the February Private Placement) of 500,000 shares of Class A common
stock to Credit Suisse First Boston Corporation at $26.31 per share, the
closing price of the Class A common stock on the New York Stock Exchange
(NYSE) on February 4, 1999, the date the stock purchase agreement was
executed. In connection with such sale, Credit Suisse First Boston Corporation
was granted certain registration rights. ATC invested the proceeds of
approximately $13.2 million in short-term investment grade securities. ATC
will continue to use such investments together with borrowings under the
Credit Facilities to fund acquisitions and construction activities.
 
Consummated Acquisitions: Since January 1, 1999, ATC has acquired various
communications sites and businesses for an aggregate preliminary purchase
price of approximately $746.0 million, including the issuance of approximately
20.7 million shares of Class A common stock valued (at the time of the
relevant agreement) at $454.8 million. The most significant transactions are
described below as the Omni Merger and TeleCom Merger.
 
Omni Merger: In February 1999, ATC consummated the Agreement and Plan of
Merger dated November 16, 1998 (the Omni Merger Agreement) with OmniAmerica,
Inc., (Omni), and ATI, pursuant to which Omni merged with and into ATI, which
was the surviving corporation (the Omni Merger). Omni owns, manages and
develops multi-use telecommunications sites for radio and television
broadcasting, paging, cellular, PCS and other wireless technologies and offers
nationwide, turn-key tower construction and installation services through its
Specialty Constructors subsidiary. Omni owns or co-owns 223 towers in 24
states including 12 towers on ten sites managed for third-party owners.
Pursuant to the Omni Merger, Omni stockholders received 1.1 shares of ATC
Class A common stock for each share of Omni common stock. In the aggregate,
ATC exchanged approximately 16.8 million shares of ATC Class A common stock in
exchange for the approximately 15.2 million shares of Omni common stock, plus
the assumption of debt of which approximately $94.3 million was paid off at
closing. Consideration for the merger also included the assumption of employee
stock options exercisable for approximately 1.0 million shares of ATC Class A
common stock.
 
TeleCom Merger: In February 1999, ATC consummated the Agreement and Plan of
Merger dated November 16, 1998 (the TeleCom Merger Agreement) with TeleCom
Towers, L.L.C., (TeleCom) and ATI, pursuant to which a newly organized
subsidiary of ATI merged with and into TeleCom, which was the surviving
corporation (the TeleCom Merger). TeleCom owns, or co-owns, approximately 271
towers and manages another 121 revenue-generating sites in 27 states. Pursuant
to the TeleCom Merger Agreement, as amended on December 18, 1998, ATC paid a
purchase price of approximately $188.9 million, subject to adjustment for
closing date working capital. ATC paid approximately $60.1 million in cash,
issued approximately 3.9 million shares of Class A common stock and assumed
approximately $48.4 million of debt, of which approximately $44.2 million was
paid at closing.
 
                                     F-24
<PAGE>
 
                  AMERICAN TOWER CORPORATION AND SUBSIDIARIES
 
            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Concluded)
 
 
 Pending Transactions:
 
ATC is a party to various agreements relating to the acquisition and
construction of towers for third parties which involve an aggregate purchase
price (a portion of which is payable in shares of Class A common stock) of
between $6.0 million and $30.0 million, depending, in certain cases, on the
cash flow of the towers to be acquired and the actual number of towers to be
built. Such transactions are subject to the satisfaction of customary closing
conditions, including, possibly, the expiration or earlier termination of the
HSR Act waiting period and most are scheduled to close in the spring or summer
of 1999.
 
The Company is also pursuing the acquisitions of tower properties and tower
businesses in new and existing locations although there are no definitive
material agreements with respect thereto.
 
13. SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED)
 
Selected quarterly financial data for the years ended December 31, 1998 and
1997 is as follows:
 
<TABLE>
<CAPTION>
                                               Three Months Ended
                                  ---------------------------------------------
                                             June
                                  March 31,   30,    September 30, December 31,
                                  --------- -------  ------------- ------------
<S>                               <C>       <C>      <C>           <C>
                                     (in thousands, except per share data)
1998:
Operating revenues..............   $17,925  $23,082     $30,478      $ 32,059
Gross profit(1).................       628   (1,210)     (3,457)       (6,232)
Loss before extraordinary
 items..........................    (1,527) (18,417)     (5,958)      (12,048)
Net loss........................    (1,527) (19,799)    (13,468)      (12,048)
Basic and diluted per common
 share:(2)
 Loss before extraordinary
  losses........................    ($0.03)  ($0.33)     ($0.06)       ($0.11)
 Net loss.......................    ($0.03)  ($0.35)     ($0.13)       ($0.11)
1997:
Operating revenues..............   $ 1,366  $ 2,015     $ 4,521      $  9,606
Gross profit(1).................       324      426         857           862
Loss before extraordinary item..       (58)    (106)       (544)         (868)
Net loss........................       (58)    (106)       (544)       (1,562)
Basic and diluted per common
 share:(2)
 Loss before extraordinary
  loss..........................    ($0.00)  ($0.00)     ($0.01)       ($0.02)
 Net loss.......................    ($0.00)  ($0.00)     ($0.01)       ($0.03)
</TABLE>
- --------
(1) Represents operating revenues less operating expenses excluding corporate
    general and administrative expenses and tower separation expenses.
(2) Prior to June 4, 1998 (the ATC Separation), basic and diluted loss per
    common share information is computed using the 48,732,000 shares that were
    outstanding upon consummation of the ATC Separation.
 
                                    * * * *
 
                                     F-25
<PAGE>
 
                                 EXHIBIT INDEX
 
  Listed below are the exhibits which are filed as part of this Form 10-K
(according to the number assigned to them in Item 601 of Regulation S-K). Each
exhibit marked by a (*) is incorporated by reference to ATC's Registration
Statement on Form S-4 (File No. 333-46025) filed on February 10, 1998. Each
exhibit marked by a (+) is incorporated by reference to ATC's Registration
Statement on Form S-1 (File No. 333-50111) filed on May 8, 1998. Each exhibit
marked by a (++) is incorporated by reference to the filing of Amendment No. 2
to ATC's Registration Statement on Form S-1 (File No. 333-52481) filed on June
30, 1998. Each exhibit marked by a (**) is incorporated by reference to the
filing of ATC's Current Report on Form 8-K filed on November 30, 1998. Each
exhibit marked by a (***) is incorporated by reference to the filing of ATC's
Current Report on Form 8-K filed on January 8, 1999. Each exhibit marked by a
(+++) is incorporated by reference to ATC's Registration Statement on Form S-4
(File No. 333-76083) filed on January 15, 1999. Each Exhibit marked by a
(++++) is incorporated by reference from Registration Statement (333-70881) on
January 21, 1999. Each exhibit marked by a (****) is incorporated by reference
to the filing of Amendment No. 1 to ATC's Registration Statement on Form S-1
(File No. 333-70881) filed on February 3, 1999. Each exhibit marked by a
(+++++) is incorporated by reference to the filing of ATC's Current Report on
Form 8-K/A filed on March 18, 1999. Exhibit numbers in parenthesis refer to
the exhibit number in the applicable filing.
 
<TABLE>
<CAPTION>
 Exhibit
   No.                 Description of Document                 Exhibit File No.
 -------               -----------------------                 ----------------
 <C>     <S>                                                   <C>
 2.1     Amendment No. 1 to Agreement and Plan of Merger,
          dated as of January 22, 1998, among ATS, American
          Tower Systems (Delaware), Inc., a Delaware
          corporation (formerly known as American Tower
          Systems, Inc.), Gearon and the Gearon
          Stockholder.......................................   (*2.2)
 
 2.2     Agreement and Plan of Merger, dated as of November
          16, 1998, by and among ATC, American Towers, Inc.,
          a wholly owned subsidiary of ATC and a Delaware
          corporation ("ATI"), and OmniAmerica, Inc., a
          Delaware corporation (Schedules and Exhibits
          omitted)..........................................   (**2.1)
 
 2.3     Agreement and Plan of Merger, dated as of November
          16, 1998, by and among ATC, ATI and TeleCom
          Towers, L.L.C., a Delaware limited liability
          company ("TeleCom") (Schedules and Exhibits
          omitted)..........................................   (**2.2)
 
 2.4     Amended and Restated Agreement and Plan of Merger,
          dated as of December 18, 1998, by and among ATC,
          ATI, ATC Merger Corporation, a Delaware
          corporation ("ATMC"), and TeleCom (Schedules and
          Exhibits omitted).................................   (***2.1)
 
 2.5     Amendment to the Amended and Restated Agreement and
          Plan of Merger, dated as of December 23, 1998, by
          and among ATC, ATI, ATMC, and TeleCom.............   (***2.2)
 
 2.6     Amendment to the Amended and Restated Agreement and
          Plan of Merger, dated as of February 26, 1999, by
          and among ATC, ATI, ATMC and TeleCom .............   (+++++2.1)
 
 3(i).1  Restated Certificate of Incorporation of ATC, as
          filed with the Secretary of State of the State of
          Delaware on June 5, 1998..........................   (++3(i).1)
 
 3(i).2  Certificate of Designation relating to Exchange
          Pay-In-Kind Preferred Stock as filed with the
          Secretary of State of the State of Delaware on
          June 4, 1998......................................   (++3(i).2)
 
 3(i).3  Certificate of Designation relating to Series A
          Redeemable Pay-In-Kind Preferred Stock, as filed
          with the Secretary of State of the State of
          Delaware on June 4, 1998..........................   (++3(i).3)
</TABLE>
<PAGE>
 
<TABLE>
<CAPTION>
 Exhibit                                                          Exhibit File
   No.                  Description of Document                       No.
 -------                -----------------------                   ------------
 <C>     <S>                                                     <C>
 3(ii).1 By-Laws of ATC.......................................   Filed herewith
                                                                 as Exhibit
                                                                 3(ii).1
 
 10.1    Parent Loan Agreement, dated as of June 16, 1998, by
          and among ATC, Toronto Dominion (Texas), Inc., as
          Administrative Agent, and the Lenders parties
          thereto (the "Parent Loan Agreement")...............   (++10.1)
 
 10.1A   First Amendment to the Parent Loan Agreement, dated
          as of October 30, 1998, by and among ATC, Toronto
          Dominion (Texas), Inc., as Administrative Agent, and
          the Lenders Parties thereto.........................   (+++10.1A)
 
 10.2A   ATS Facility A Loan Agreement, dated as of June 16,
          1998 among American Tower Systems, L.P. ("ATSLP")
          and ATSI, as borrowers, and Toronto Dominion
          (Texas), Inc., as Administrative Agent, and the
          Banks parties thereto (the "Facility A Loan
          Agreement").........................................   (++10.2A)
 
 10.2B   ATS Facility B Loan Agreement, dated as of June 16,
          1998, by and among ATSLP and ATSI, as borrowers, and
          Toronto Dominion (Texas), Inc., and the Banks
          parties thereto (the "Facility B Loan Agreement")...   (++10.2B)
 
 10.3    First Amendment to the ATS Facility A Loan Agreement,
          dated as of October 30, 1998 among ATSLP and ATI, as
          borrowers, and Toronto Dominion (Texas), Inc., as
          Administrative Agent, and the Banks parties
          thereto.............................................   (+++10.3)
 
 10.4    First Amendment to the ATS Facility B Loan Agreement,
          dated as of October 30, 1998 among ATSLP and ATI, as
          borrowers, and Toronto Dominion (Texas), Inc., as
          Administrative Agent, and the Banks parties
          thereto.............................................   (+++10.4)
 
 10.5    American Tower Systems Corporation 1997 Stock Option
          Plan, dated as of November 5, 1997, as amended and
          restated on April 27, 1998..........................   (+10.26)
 
 10.6    American Tower Systems Corporation Stock Purchase
          Agreement, dated as of January 8, 1998, by and among
          ATC and the Purchasers..............................   (*10.27)
 
 10.7    Employment Agreement, dated as of January 22, 1988,
          by and between ATI and J. Michael Gearon, Jr........   (*10.28)
 
 10.8    Letter of Agreement, dated as of April 13, 1998, by
          and between ATC and Douglas Wiest...................   (+++10.22)
 
 10.9    ARS-ATS Separation Agreement, dated as of June 4,
          1998 by and among American Radio Systems
          Corporation, a Delaware Corporation ("ARS"), ATC,
          and CBS Corporation.................................   (++10.30)
 10.10   Securities Purchase Agreement, dated as of June 4,
          1998, by and among ATC, Credit Suisse First Boston
          Corporation and each of the Purchasers named
          therein.............................................   (++10.30)
 10.11   Registration Rights Agreement, dated as of June 4,
          1998, by and among ATC, Credit Suisse First Boston
          Corporation and each of the Parties named therein...   (++10.31)
</TABLE>
<PAGE>
 
<TABLE>
<CAPTION>
 Exhibit                                                           Exhibit File
   No.                   Description of Document                       No.
 -------                 -----------------------                   ------------
 <C>     <S>                                                      <C>
 10.11   Registration Rights Agreement, dated as of January 22,   Incorporated
          1998, by and among ATC and each of the Parties named    by reference
          therein..............................................   to Exhibit
                                                                  10.3 from the
                                                                  Company's
                                                                  Quarterly
                                                                  Report on Form
                                                                  10-Q (File No.
                                                                  001-14194)
                                                                  dated August
                                                                  14, 1998
 10.12   Stock Purchase Agreement, dated as of February 4,        Filed herewith
          1999, by and among ATC and Credit Suisse First Boston   as Exhibit
          Corporation..........................................   10.13
 10.13   Registration Rights Agreement, dated as of February 4,   Filed herewith
          1999, by and among ATC and Credit Suisse First Boston   as Exhibit
          Corporation .........................................   10.14
 10.14   Amended and Restated Registration Rights Agreement,      (+++++10.1)
          dated as of February 25, 1999, by and among ATC and
          each of the Parties named therein....................
 21      Subsidiaries of ATC...................................   Filed herewith
                                                                  as Exhibit 21
 23      Independent Auditors' Consent--Deloitte & Touche LLP..   Filed herewith
                                                                  as Exhibit 23
 27      Financial Data Schedule...............................   Filed herewith
                                                                  as Exhibit 27
</TABLE>

<PAGE>
                                                                         EXHIBIT
                                                                         3(ii).1
 
                                    BY-LAWS

                                      OF

                          AMERICAN TOWER CORPORATION
                           (a Delaware Corporation)
<PAGE>
 
                          AMERICAN TOWER CORPORATION
                           (a Delaware Corporation)

                                    BY-LAWS
                               TABLE OF CONTENTS

                                                                  Page
                                                                  ----
ARTICLE I.             OFFICES ..........................................    1
                       
         SECTION 1.    Registered Office ................................    1
         SECTION 2.    Other Offices ....................................    1
                       
ARTICLE II.            SEAL .............................................    1
                       
ARTICLE III.           MEETINGS OF STOCKHOLDERS .........................    1
                       
         SECTION 1.    Place of Meeting .................................    1
         SECTION 2.    Annual Meetings ..................................    1
         SECTION 3.    Special Meetings .................................    2
         SECTION 4.    Notice ...........................................    2
         SECTION 5.    Quorum and Adjournments ..........................    2
         SECTION 6.    Votes; Proxies ...................................    3
         SECTION 7.    Organization .....................................    4
         SECTION 8.    Consent of Stockholders in Lieu of Meeting .......    4
                       
ARTICLE IV.            DIRECTORS ........................................    5
                       
         SECTION 1.    Number ...........................................    5
         SECTION 2.    Term of Office ...................................    5
         SECTION 3.    Vacancies ........................................    5
         SECTION 4.    Removal by Stockholders ..........................    5
         SECTION 5.    Meetings .........................................    5
         SECTION 6.    Votes ............................................    6
         SECTION 7.    Quorum and Adjournment ...........................    6
         SECTION 8.    Compensation .....................................    6
         SECTION 9.    Action By Consent of Directors ...................    6
                       
ARTICLE V.             COMMITTEES OF DIRECTORS ..........................    7
                       
         SECTION 1.    Executive Committee ..............................    7
         SECTION 2.    Audit Committee ..................................    8
         SECTION 3.    Other Committees .................................    9
         SECTION 4.    Term of Office ...................................    9
<PAGE>
 
ARTICLE VI.            OFFICERS .........................................   10
                       
         SECTION 1.    Officers .........................................   10
         SECTION 2.    Vacancies ........................................   10
         SECTION 3.    Chairman of the Board ............................   10
         SECTION 4.    President ........................................   10
         SECTION 5.    Executive Vice Presidents and Vice Presidents ....   10
         SECTION 6.    Secretary ........................................   10
         SECTION 7.    Assistant Secretaries ............................   11
         SECTION 8.    Treasurer ........................................   11
         SECTION 9.    Assistant Treasurers .............................   11
         SECTION 10.   Controller .......................................   11
         SECTION 11.   Assistant Controller .............................   11
         SECTION 12.   Subordinate Officers .............................   11
         SECTION 13.   Compensation .....................................   12
         SECTION 14.   Removal ..........................................   12
         SECTION 15.   Bonds ............................................   12
                       
ARTICLE VII.           CERTIFICATES OF STOCK ............................   12
                       
         SECTION 1.    Form and Execution of Certificates ...............   12
         SECTION 2.    Transfer of Shares ...............................   13
         SECTION 3.    Closing of Transfer Books ........................   13
         SECTION 4.    Fixing Date for Determination of Stockholders 
                       of Record ........................................   13
         SECTION 5.    Lost or Destroyed Certificates ...................   14
         SECTION 6.    Uncertificated Shares ............................   15
                       
ARTICLE VIII.          EXECUTION OF DOCUMENTS ...........................   15
                       
         SECTION 1.    Execution of Checks, Notes, etc ..................   15
         SECTION 2.    Execution of Contracts, Assignments, etc .........   15
         SECTION 3.    Execution of Proxies .............................   15
                       
ARTICLE IX.            INSPECTION OF BOOKS ..............................   16
                       
ARTICLE X.             FISCAL YEAR ......................................   16
                       
ARTICLE XI.            AMENDMENTS .......................................   16
                       
ARTICLE XII.           INDEMNIFICATION ..................................   16
                       
         SECTION 1.    Indemnification ..................................   16
         SECTION 2.    Authorization ....................................   17
         SECTION 3.    Expense Advance ..................................   18
         SECTION 4.    Nonexclusivity ...................................   18
<PAGE>
 
         SECTION 5.    Insurance ........................................   18
         SECTION 6.    "The Corporation" ................................   18
         SECTION 7.    Other Indemnification ............................   19
         SECTION 8.    Other Definitions ................................   19
         SECTION 9.    Continuation of Indemnification ..................   19
         SECTION 10.   Amendment or Repeal ..............................   19
<PAGE>
 
                          AMERICAN TOWER CORPORATION

                           (a Delaware Corporation)


                                     ----  

                                    BY-LAWS


                                     ----

                                   ARTICLE I

                                     ----


                                    OFFICES

         SECTION 1. Registered Office. The registered office of the Corporation
                    -----------------
shall be located in Wilmington, County of New Castle, State of Delaware, and the
name of the resident agent in charge thereof shall be Corporation Service
Company.

         SECTION 2. Other Offices. The Corporation may also have offices at such
                    -------------
other places, within or without the State of Delaware, as the Board of Directors
may from time to time appoint or the business of the Corporation may require.

                                  ARTICLE II
                                  ----------

                                     SEAL

         The seal of the Corporation shall, subject to alteration by the Board
of Directors, consist of a flat-faced circular die with the word "Delaware",
together with the name of the Corporation and the year of incorporation, cut or
engraved thereon.

                                  ARTICLE III
                                  -----------

                           MEETINGS OF STOCKHOLDERS

         SECTION 1. Place of Meeting. Meetings of the stockholders shall be held
                    ----------------
either within or without the State of Delaware at such place as the Board of
Directors may fix from time to time.

         SECTION 2. Annual Meetings. The annual meeting of stockholders shall be
                    ---------------
held for the election of directors on such date and at such time as the Board of
Directors may fix from time to time. Any other proper business may be transacted
at the annual meeting.
<PAGE>
 
By-laws of American Tower Corporation
A Delaware Corporation
Page 2

         SECTION 3. Special Meetings. Special meetings of the stockholders for
                    ----------------
any purpose or purposes may be called by the Chairman of the Board of Directors,
if there be one, the President or by the directors (either by written instrument
signed by a majority or by resolution adopted by a vote of the majority), and
special meetings shall be called by the President or the Secretary whenever
stockholders owning a majority of the capital stock issued, outstanding and
entitled to vote so request in writing. Such request of stockholders shall state
the purpose or purposes of the proposed meeting.

         SECTION 4. Notice. Written or printed notice of every meeting of
                    ------
stockholders, annual or special, stating the hour, date and place thereof, and
the purpose or purposes in general terms for which the meeting is called shall,
not less than ten (10) days, or such longer period as shall be provided by law,
the Certificate of Incorporation, these By-Laws, or otherwise, and not more than
sixty (60) days before such meeting, be served upon or mailed to each
stockholder entitled to vote thereat, at the address of such stockholder as it
appears upon the stock records of the Corporation or, if such stockholder shall
have filed with the Secretary of the Corporation a written request that notices
be mailed to some other address, then to the address designated in such request.

         Notice of the hour, date, place and purpose of any meeting of
stockholders may be dispensed with if every stockholder entitled to vote thereat
shall attend either in person or by proxy and shall not, at the beginning of the
meeting, object to the holding of such meeting because the meeting has not been
lawfully called or convened, or if every absent stockholder entitled to such
notice shall in writing, filed with the records of the meeting, either before or
after the holding thereof, waive such notice.

         SECTION 5. Quorum and Adjournments. Except as otherwise provided by law
                    ----------------------- 
or by the Certificate of Incorporation, the presence in person or by proxy at
any meeting of stockholders of the holders of a majority of the shares of the
capital stock of the Corporation issued and outstanding and entitled to vote
thereat, shall be requisite and shall constitute a quorum. If two or more
classes of stock are entitled to vote as separate classes upon any question,
then, in the case of each such class, a quorum for the consideration of such
question shall, except as otherwise provided by law or by the Certificate of
Incorporation, consist of a majority in interest of all stock of that class
issued, outstanding and entitled to vote. If a majority of the shares of capital
stock of the Corporation issued and outstanding and entitled to vote thereat or,
where a larger quorum is required, such quorum, shall not be represented at any
meeting of the stockholders regularly called, the holders of a majority of the
shares present or represented by proxy and entitled to vote thereat shall have
power to adjourn the meeting to another time, or to another time and place,
without notice other than announcement of adjournment at the meeting, and there
may be successive adjournments for like cause and in like manner until the
requisite amount of shares entitled to vote at such meeting shall be
represented; provided, however, that if the adjournment is for more than thirty
(30) days, notice of the hour, date and place of the adjourned meeting shall be
given to each stockholder entitled to vote thereat. Subject to the requirements
of law and the Certificate of Incorporation, on any issue on which two or more
classes of stock are entitled to vote separately, no adjournment shall be taken
with respect to any class for which a quorum is
<PAGE>
 
By-laws of American Tower Corporation
A Delaware Corporation
Page 3

present unless the Chairman of the meeting otherwise directs. At any meeting
held to consider matters which were subject to adjournment for want of a quorum
at which the requisite amount of shares entitled to vote thereat shall be
represented, any business may be transacted which might have been transacted at
the meeting as originally noticed.

         SECTION 6. Votes; Proxies. Except as otherwise provided in the
                    --------------
Certificate of Incorporation, at each meeting of stockholders, every stockholder
of record at the closing of the transfer books, if closed, or on the date set by
the Board of Directors for the determination of stockholders entitled to vote at
such meeting, shall have one vote for each share of stock entitled to vote which
is registered in such stockholder's name on the books of the Corporation, and,
in the election of directors, may vote cumulatively to the extent, if any, and
in the manner authorized in the Certificate of Incorporation.

         At each such meeting every stockholder entitled to vote shall be
entitled to do so in person, or by proxy appointed by an instrument in writing
or as otherwise permitted by law subscribed by such stockholder and bearing a
date not more than three (3) years prior to the meeting in question, unless said
instrument provides for a longer period during which it is to remain in force. A
duly executed proxy shall be irrevocable if it states that it is irrevocable and
if, and only as long as, it is coupled with an interest sufficient in law to
support an irrevocable power. A proxy may be made irrevocable regardless of
whether the interest with which it is coupled is an interest in the stock itself
or any interest in the Corporation generally. A stockholder may revoke any proxy
which is not irrevocable by attending the meeting and voting in person or by
filing with the Secretary of the Corporation an instrument in writing or as
otherwise permitted by law revoking the proxy or another duly executed proxy
bearing a later date.

         Voting at meetings of stockholders need not be by written ballot and,
except as otherwise provided by law, need not be conducted by inspectors of
election unless so determined by the Chairman of the meeting or by the holders
of shares of stock having a majority of the votes which could be cast by the
holders of all outstanding shares of stock entitled to vote thereon which are
present in person or represented by proxy at such meeting. If it is required or
determined that inspectors of election be appointed, the Chairman shall appoint
two inspectors of election, who shall first take and subscribe an oath or
affirmation faithfully to execute the duties of inspectors at such meeting with
strict impartiality and according to the best of their ability. The inspectors
so appointed shall take charge of the polls and, after the balloting, shall make
a certificate of the result of the vote taken. No director or candidate for the
office of director shall be appointed as such inspector.

         At any meeting at which a quorum is present, a plurality of the votes
properly cast for election to fill any vacancy on the Board of Directors shall
be sufficient to elect a candidate to fill such vacancy, and a majority of the
votes properly cast upon any other question shall decide the question, except in
any case where a larger vote is required by law, the Certificate of
Incorporation, these By-Laws, or otherwise.
<PAGE>
 
By-laws of American Tower Corporation
A Delaware Corporation
Page 4

         SECTION 7. Organization. The Chairman of the Board, if there be one, or
                    ------------
in his or her absence the Vice Chairman, or in the absence of a Vice Chairman,
the President, or in the absence of the President, a Vice President, shall call
meetings of the stockholders to order and shall act as chairman thereof. The
Secretary of the Corporation, if present, shall act as secretary of all meetings
of stockholders, and, in his or her absence, the presiding officer may appoint a
secretary.

         SECTION 8. Consent of Stockholders in Lieu of Meeting. Unless otherwise
                    ------------------------------------------
restricted by the Certificate of Incorporation, any action required or permitted
by the Delaware General Corporation Law to be taken at any annual or special
meeting of the stockholders of the Corporation, may be taken without a meeting,
without prior notice and without a vote, if a consent or consents in writing,
setting forth the action so taken, shall be signed by the holders of outstanding
stock having not less than the minimum number of votes that would be necessary
to authorize or take such action at a meeting at which all shares entitled to
vote thereon were present and voted and shall be delivered to the Corporation by
delivery to its registered office in Delaware, its principal place of business,
or an officer or agent of the Corporation having custody of the book in which
proceedings of meetings of stockholders are recorded. Delivery made to the
Corporation's registered office shall be by hand or by certified or registered
mail, return receipt requested.

         Every written consent shall bear the date of signature of each
stockholder who signs the consent and no written consent shall be effective to
take the corporate action referred to therein unless, within sixty (60) days of
the earliest dated consent delivered in the manner required by this section to
the Corporation, written consents signed by a sufficient number of stockholders
to take action are delivered to the corporation by delivery to its registered
office in Delaware, its principal place of business, or an officer or agent of
the Corporation having custody of the book in which proceedings of meetings of
stockholders are recorded. Delivery made to the Corporation's registered office
shall be by hand or by certified or registered mail, return receipt requested.

         Prompt notice of the taking of the corporate action without a meeting
by less than unanimous written consent shall be given to those stockholders who
have not consented in writing. In the event that the action which is consented
to is such as would have required the filing of a certificate under any section
of the Delaware General Corporation Law other than Section 228 thereof, if such
action had been voted on by stockholders at a meeting thereof, the certificate
filed under such other section shall state, in lieu of any statement required by
such section concerning any vote of stockholders, that written consent has been
given in accordance with Section 228 of the Delaware General Corporation Law,
and that written notice has been given as provided in such Section 228.
<PAGE>
 
By-laws of American Tower Corporation
A Delaware Corporation
Page 5


                                  ARTICLE IV
                                  ----------

                                   DIRECTORS

         SECTION 1. Number. The business and affairs of the Corporation shall be
                    ------
conducted and managed by a Board of Directors consisting of not less than one
director, none of whom needs to be a stockholder. The number of directors for
each year shall be fixed at each annual meeting of stockholders, but if the
number is not so fixed, the number shall remain as it stood immediately prior to
such meeting.

         At each annual meeting of stockholders, the stockholders shall elect
directors. Each director so elected shall hold office, subject to the provisions
of law, the Certificate of Incorporation, these By-Laws, or otherwise, until the
next annual meeting of stockholders or until his or her successor is elected and
qualified.

         At any time during any year, except as otherwise provided by law, the
Certificate of Incorporation, these By-Laws, or otherwise, the number of
directors may be increased or reduced, in each case by vote of a majority of the
stock issued and outstanding and present in person or represented by proxy and
entitled to vote for the election of directors or a majority of the directors in
office at the time of such increase or decrease, regardless of whether such
majority constitutes a quorum.

         SECTION 2. Term of Office. Each director shall hold office until the
                    --------------
next annual meeting of stockholders and until his or her successor is duly
elected and qualified or until his or her earlier death or resignation, subject
to the right of the stockholders at any time to remove any director or directors
as provided in Section 4 of this Article.

         SECTION 3. Vacancies. If any vacancy shall occur among the directors,
                    ---------
or if the number of directors shall at any time be increased, the directors then
in office, although less than a quorum, by a majority vote may fill the
vacancies or newly- created directorships, or any such vacancies or
newly-created directorships may be filled by the stockholders at any meeting.

         SECTION 4. Removal by Stockholders. Except as otherwise provided by
                    -----------------------
law, the Certificate of Incorporation or otherwise, the holders of record of the
capital stock of the Corporation entitled to vote for the election of directors
may, by a majority vote, remove any director or directors, with or without
cause, and, in their discretion, elect a new director or directors in place
thereof.

         SECTION 5. Meetings. Meetings of the Board of Directors shall be held
                    --------
at such place, within or without the State of Delaware, as may from time to time
be fixed by resolution of the Board of Directors or by the Chairman of the
Board, if there be one, or by the President, and as may be specified in the
notice or waiver of notice of any meeting. Meetings may be held at any 
<PAGE>
 
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A Delaware Corporation
Page 6

time upon the call of the Chairman of the Board, if there be one, or the
President or any two (2) of the directors in office by oral, telegraphic, telex,
telecopy or other form of electronic transmission, or written notice, duly
served or sent or mailed to each director not less than twenty-four (24) hours
before such meeting, except that, if mailed, not less than seventy two (72)
hours before such meeting.

         Meetings may be held at any time and place without notice if all the
directors are present and do not object to the holding of such meeting for lack
of proper notice or if those not present shall, in writing or by telegram,
telex, telecopy or other form of electronic transmission, waive notice thereof.
A regular meeting of the Board may be held without notice immediately following
the annual meeting of stockholders at the place where such meeting is held.
Regular meetings of the Board may also be held without notice at such time and
place as shall from time to time be determined by resolution of the Board.
Except as otherwise provided by law, the Certificate of Incorporation or
otherwise, neither the business to be transacted at, nor the purpose of, any
regular or special meeting of the Board of Directors or any committee thereof
need be specified in any written waiver of notice.

         Members of the Board of Directors or any committee thereof may
participate in a meeting of such Board or committee by means of conference
telephone or similar communications equipment by means of which all persons
participating in the meeting can hear each other and participation in a meeting
pursuant to the foregoing provisions shall constitute presence in person at the
meeting.

         SECTION 6. Votes. Except as otherwise provided by law, the Certificate
                    -----
of Incorporation or otherwise, the vote of the majority of the directors present
at a meeting at which a quorum is present shall be the act of the Board of
Directors.

         SECTION 7. Quorum and Adjournment. Except as otherwise provided by law,
                    ----------------------
the Certificate of Incorporation or otherwise, a majority of the directors shall
constitute a quorum for the transaction of business. If at any meeting of the
Board there shall be less than a quorum present, a majority of those present may
adjourn the meeting from time to time without notice other than announcement of
the adjournment at the meeting, and at such adjourned meeting at which a quorum
is present any business may be transacted which might have been transacted at
the meeting as originally noticed.

         SECTION 8. Compensation. Directors shall receive compensation for their
                    ------------
services, as such, and for service on any Committee of the Board of Directors,
as fixed by resolution of the Board of Directors and for expenses of attendance
at each regular or special meeting of the Board or any Committee thereof.
Nothing in this Section shall be construed to preclude a director from serving
the Corporation in any other capacity and receiving compensation therefor.

         SECTION 9. Action By Consent of Directors. Any action required or
                    ------------------------------
permitted to be taken at any meeting of the Board of Directors or of any
committee thereof may be taken without 
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A Delaware Corporation
Page 7

a meeting if all members of the Board or committee, as the case may be, consent
thereto in writing, and the writing or writings are filed with the minutes of
proceedings of the Board or committee. Such consent shall be treated as a vote
adopted at a meeting for all purposes. Such consents may be executed in one or
more counterparts and not every Director or committee member need sign the same
counterpart.

                                   ARTICLE V
                                   ---------

                            COMMITTEES OF DIRECTORS

         SECTION 1. Executive Committee. The Board of Directors may, by
                    -------------------
resolution passed by a majority of the whole Board, appoint an Executive
Committee of one (1) or more members, to serve during the pleasure of the Board,
to consist of such directors as the Board may from time to time designate. The
Board of Directors shall designate the Chairman of the Executive Committee.

         (a)      Procedure. The Executive Committee shall, by a vote of a
                  ---------
                  majority of its members, fix its own times and places of
                  meeting, determine the number of its members constituting a
                  quorum for the transaction of business, and prescribe its own
                  rules of procedure, no change in which shall be made save by a
                  majority vote of its members.

         (b)      Responsibilities. During the intervals between the meetings
                  ----------------
                  of the Board of Directors, except as otherwise provided by
                  the Board of Directors in establishing such Committee or
                  otherwise, the Executive Committee shall possess and may
                  exercise all the powers of the Board in the management and
                  direction of the business and affairs of the Corporation;
                  provided, however, that the Executive Committee shall not,
                  except to the extent the Certificate of Incorporation or the
                  resolution providing for the issuance of shares of stock
                  adopted by the Board of Directors as provided in Section
                  151(a) of the Delaware General Business Corporation Law,
                  have the power:

                             (i)    to amend or authorize  the amendment of the
                                    Certificate of Incorporation or these 
                                    By-Laws;

                            (ii)    to authorize the issuance of stock in excess
                                    of one million (1,000,000) shares in any
                                    single transaction or group of related
                                    transactions;

                           (iii)    to authorize the payment of any dividend;

                            (iv)    to adopt an agreement of merger or
                                    consolidation pursuant to which the
                                    Corporation will merge or consolidate or to
                                    recommend to the 
<PAGE>
 
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A Delaware Corporation
Page 8

                                    stockholders the sale, lease or exchange of
                                    all or substantially all the property and
                                    business of the Corporation;

                            (v)     to recommend to the stockholders a
                                    dissolution, or a revocation of a
                                    dissolution, of the Corporation; or

                           (vi)     to adopt a certificate of ownership and
                                    merger pursuant to Section 253 of the
                                    Delaware Business Corporation Law; and
                                    further

          (c)  Reports. The Executive Committee shall keep regular minutes of
               -------
               its proceedings, and all action by the Executive Committee shall
               be reported promptly to the Board of Directors. Such action shall
               be subject to review, amendment and repeal by the Board, provided
               that no rights of third parties shall be adversely affected by
               such review, amendment or repeal.

          (d)  Appointment of Additional Members. In the absence or
               ---------------------------------
               disqualification of any member of the Executive Committee, the
               member or members thereof present at any meeting and not
               disqualified from voting, whether or not constituting a quorum,
               may unanimously appoint another member of the Board of Directors
               to act at the meeting in place of any such absent or disqualified
               member.

          SECTION 2. Audit Committee. The Board of Directors may, by resolution
                     ---------------
passed by a majority of the whole Board, appoint an Audit Committee of one (1)
or more members who shall not be officers or employees of the Corporation to
serve during the pleasure of the Board. The Board of Directors shall designate
the Chairman of the Audit Committee.

          (a)  Procedure. The Audit Committee, by a vote of a majority of its
               ---------
               members, shall fix its own times and places of meeting, shall
               determine the number of its members constituting a quorum for the
               transaction of business, and shall prescribe its own rules of
               procedure, no change in which shall be made save by a majority
               vote of its members.

          (b)  Responsibilities. The Audit Committee shall review the annual
               ----------------
               financial statements of the Corporation prior to their submission
               to the Board of Directors, shall consult with the Corporation's
               independent auditors, and may examine and consider such other
               matters in relation to the internal and external audit of the
               Corporation's accounts and in relation to the financial affairs
               of the Corporation and its accounts, including the selection and
               retention of independent auditors, as the Audit Committee may, in
               its discretion, determine to be desirable.

          (c)  Reports. The Audit Committee shall keep regular minutes of its
               -------
               proceedings, and all action by the Audit Committee shall, from
               time to time, be reported to the Board of Directors as it shall
               direct. Such action shall be subject to review, 
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A Delaware Corporation
Page 9

               amendment and repeal by the Board, provided that no rights of
               third parties shall be adversely affected by such review,
               amendment or repeal.

          (d)  Appointment of Additional Members. In the absence or
               ---------------------------------
               disqualification of any member of the Audit Committee, the member
               or members thereof present at any meeting and not disqualified
               from voting, whether or not constituting a quorum, may
               unanimously appoint another member of the Board of Directors to
               act at the meeting in place of any such absent or disqualified
               member.

          SECTION 3. Other Committees. The Board of Directors may, by resolution
                     ----------------
passed by a majority of the whole Board, at any time appoint one or more other
committees from and outside of its own number. Every such committee must include
at least one member of the Board of Directors. The Board may from time to time
designate or alter, within the limits permitted by law, the Certificate of
Incorporation and this Article, if applicable, the duties, powers and number of
members of such other committees or change their membership, and may at any time
abolish such other committees or any of them.

          (a)  Procedure. Each committee, appointed pursuant to this Section,
               ---------
               shall, by a vote of a majority of its members, fix its own times
               and places of meeting, determine the number of its members
               constituting a quorum for the transaction of business, and
               prescribe its own rules of procedure, no change in which shall be
               made save by a majority vote of its members.

          (b)  Responsibilities. Each committee, appointed pursuant to this
               ---------------- 
               Section, shall exercise the powers assigned to it by the Board of
               Directors in its discretion.

          (c)  Reports . Each committee appointed pursuant to this Section shall
               -------
               keep regular minutes of proceedings, and all action by each such
               committee shall, from time to time, be reported to the Board of
               Directors as it shall direct. Such action shall be subject to
               review, amendment and repeal by the Board, provided that no
               rights of third parties shall be adversely affected by such
               review, amendment or repeal.

          (d)  Appointment of Additional Members. In the absence or
               ---------------------------------    
               disqualification of any member of each committee, appointed
               pursuant to this Section, the member or members thereof present
               at any meeting and not disqualified from voting, whether or not
               constituting a quorum, may unanimously appoint another member of
               the Board of Directors (or, to the extent permitted, another
               person) to act at the meeting in place of any such absent or
               disqualified member.

          SECTION 4. Term of Office. Each member of a committee shall hold
                     --------------
office until the first meeting of the Board of Directors following the annual
meeting of stockholders (or until such other time as the Board of Directors may
determine, either in the vote establishing the committee or at the election of
such member or otherwise) and until his or her successor is elected and
<PAGE>
 
By-laws of American Tower Corporation
A Delaware Corporation
Page 10

qualified, or until he or she sooner dies, resigns, is removed, is replaced
by change of membership or becomes disqualified by ceasing to be a director
(where membership on the Board is required), or until the committee is sooner
abolished by the Board of Directors.

                                  ARTICLE VI
                                  ----------

                                   OFFICERS

          SECTION 1. Officers. The Board of Directors shall elect a President, a
                     --------
Secretary and a Treasurer, and, in their discretion, may elect a Chairman of the
Board, a Vice Chairman of the Board, a Controller, and one or more Executive
Vice Presidents, Vice Presidents, Assistant Secretaries, Assistant Treasurers
and Assistant Controllers as deemed necessary or appropriate. Such officers
shall be elected annually by the Board of Directors at its first meeting
following the annual meeting of stockholders (or at such other meeting as the
Board of Directors determines), and each shall hold office for the term provided
by the vote of the Board, except that each will be subject to removal from
office in the discretion of the Board as provided herein. The powers and duties
of more than one office may be exercised and performed by the same person.

          SECTION 2. Vacancies. Any vacancy in any office may be filled for the
                     ---------
unexpired portion of the term by the Board of Directors, at any regular or
special meeting.

          SECTION 3. Chairman of the Board. The Chairman of the Board of
                     ---------------------
Directors, if elected, shall be a member of the Board of Directors and shall
preside at its meetings. The Chairman, if other than the President, shall advise
and counsel with the President, and shall perform such duties as from time to
time may be assigned to him or her by the Board of Directors.

          SECTION 4. President. The President shall be the chief executive
                     ---------
officer of the Corporation. Subject to the directions of the Board of Directors,
the President shall have and exercise direct charge of and general supervision
over the business and affairs of the Corporation and shall perform all duties
incident to the office of the chief executive officer of a corporation and such
other duties as from time to time may be assigned to him or her by the Board of
Directors. The President may but need not be a member of the Board of Directors.

          SECTION 5. Executive Vice Presidents and Vice Presidents. Each
                     ---------------------------------------------
Executive Vice President and Vice President shall have and exercise such powers
and shall perform such duties as from time to time may be assigned to him or to
her by the Board of Directors or the President.

          SECTION 6. Secretary. The Secretary shall keep the minutes of all
                     ---------
meetings of the stockholders and of the Board of Directors in books provided for
the purpose; shall see that all notices are duly given in accordance with the
provisions of law and these By-Laws; the Secretary shall be custodian of the
records and of the corporate seal or seals of the Corporation; shall see that
the corporate seal is affixed to all documents the execution of which, on behalf
of the
<PAGE>
 
By-laws of American Tower Corporation
A Delaware Corporation
Page 11

Corporation under its seal, is duly authorized, and, when the seal is so
affixed, he or she may attest the same; the Secretary may sign, with the
President, an Executive Vice President or a Vice President, certificates of
stock of the Corporation; and, in general, the Secretary shall perform all
duties incident to the office of secretary of a corporation, and such other
duties as from time to time may be assigned to him or her by the Board of
Directors.

         SECTION 7. Assistant Secretaries. The Assistant Secretaries in order of
                    ---------------------
their seniority shall, in the absence or disability of the Secretary, perform
the duties and exercise the powers of the Secretary and shall perform such other
duties as the Board of Directors shall prescribe or as from time to time may be
assigned by the Secretary.

         SECTION 8. Treasurer. The Treasurer shall have charge of and be
                    ---------   
responsible for all funds, securities, receipts and disbursements of the
Corporation, and shall deposit, or cause to be deposited, in the name of the
Corporation, all monies or other valuable effects in such banks, trust companies
or other depositaries as shall, from time to time, be selected by the Board of
Directors; may endorse for collection on behalf of the Corporation checks, notes
and other obligations; may sign receipts and vouchers for payments made to the
Corporation; may sign checks of the Corporation, singly or jointly with another
person as the Board of Directors may authorize, and pay out and dispose of the
proceeds under the direction of the Board; the Treasurer shall render to the
President and to the Board of Directors, whenever requested, an account of the
financial condition of the Corporation; the Treasurer may sign, with the
President, or an Executive Vice President or a Vice President, certificates of
stock of the Corporation; and in general, shall perform all the duties incident
to the office of treasurer of a corporation, and such other duties as from time
to time may be assigned by the Board of Directors. Unless the Board of Directors
shall otherwise determine, the Treasurer shall be the chief financial officer of
the Corporation.

         SECTION 9. Assistant Treasurers. The Assistant Treasurers in order of
                    --------------------
their seniority shall, in the absence or disability of the Treasurer, perform
the duties and exercise the powers of the Treasurer and shall perform such other
duties as the Board of Directors shall prescribe or as from time to time may be
assigned by the Treasurer.

         SECTION 10. Controller. The Controller, if elected, shall be the chief
                     ----------
accounting officer of the Corporation and shall perform all duties incident to
the office of a controller of a corporation, and, in the absence of or
disability of the Treasurer or any Assistant Treasurer, perform the duties and
exercise the powers of the Treasurer and shall perform such other duties as the
Board of Directors shall prescribe or as from time to time may be assigned by
the President or the Treasurer.

         SECTION 11. Assistant Controllers. The Assistant Controllers in order
                     ---------------------
of their seniority shall, in the absence or disability of the Controller,
perform the duties and exercise the powers of the Controller and shall perform
such other duties as the Board of Directors shall prescribe or as from time to
time may be assigned by the Controller.
<PAGE>
 
By-laws of American Tower Corporation
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Page 12

         SECTION 12. Subordinate Officers. The Board of Directors may appoint
                     --------------------
such subordinate officers as it may deem desirable. Each such officer shall hold
office for such period, have such authority and perform such duties as the Board
of Directors may prescribe. The Board of Directors may, from time to time,
authorize any officer to appoint and remove subordinate officers and to
prescribe the powers and duties thereof.

         SECTION 13. Compensation. The Board of Directors shall fix the
                     ------------
compensation of all officers of the Corporation. It may authorize any officer,
upon whom the power of appointing subordinate officers may have been conferred,
to fix the compensation of such subordinate officers.

        SECTION 14. Removal. Any officer of the Corporation may be removed, with
                    -------
or without cause, by action of the Board of Directors.

         SECTION 15. Bonds. The Board of Directors may require any officer of
                     -----
the Corporation to give a bond to the Corporation, conditional upon the faithful
performance of his or her duties, with one or more sureties and in such amount
as may be satisfactory to the Board of Directors.

                                  ARTICLE VII
                                  -----------

                              CERTIFICATES OF STOCK
 
         SECTION 1. Form and Execution of Certificates. The interest of each
                    ----------------------------------
stockholder of the Corporation shall be evidenced by a certificate or
certificates for shares of stock in such form as the Board of Directors may from
time to time prescribe. The certificates of stock of each class shall be
consecutively numbered and signed by the Chairman or Vice Chairman of the Board,
if any, the President, an Executive Vice President or a Vice President and by
the Secretary, an Assistant Secretary, the Treasurer or an Assistant Treasurer
of the Corporation, and may be countersigned and registered in such manner as
the Board of Directors may by resolution prescribe, and shall bear the corporate
seal or a printed or engraved facsimile thereof. Where any such certificate is
signed by a transfer agent or transfer clerk acting on behalf of the
Corporation, the signatures of any such Chairman, Vice Chairman, President,
Executive Vice President, Vice President, Treasurer, Assistant Treasurer,
Secretary or Assistant Secretary may be facsimiles, engraved or printed. In case
any officer or officers, who shall have signed, or whose facsimile signature or
signatures shall have been used on, any such certificate or certificates, shall
cease to be such officer or officers, whether because of death, resignation or
otherwise, before such certificate or certificates shall have been delivered by
the Corporation, such certificate or certificates may nevertheless be issued and
delivered by the Corporation as though the person or persons who signed such
certificate or certificates or whose facsimile signature or signatures shall
have been used thereon had not ceased to be such officer or officers.

         In case the corporate seal which has been affixed to, impressed on, or
reproduced in any such certificate or certificates shall cease to be the seal of
the Corporation before such certificate 
<PAGE>
 
By-laws of American Tower Corporation
A Delaware Corporation
Page 13

or certificates have been delivered by the Corporation, such certificate or
certificates may nevertheless be issued and delivered by the Corporation as
though the seal affixed thereto, impressed thereon or reproduced therein had not
ceased to be the seal of the Corporation.

         Every certificate for shares of stock which are subject to any
restriction on transfer pursuant to law, the Certificate of Incorporation, these
By-Laws, or any agreement to which the Corporation is a party, shall have the
restriction noted conspicuously on the certificate, and shall also set forth, on
the face or back, either the full text of the restriction or a statement of the
existence of such restriction and (except if such restriction is imposed by law)
a statement that the Corporation will furnish a copy thereof to the holder of
such certificate upon written request and without charge.

         Every certificate issued when the Corporation is authorized to issue
more than one class or series of stock shall set forth on its face or back
either the full text of the preferences, voting powers, qualifications, and
special and relative rights of the shares of each class and series authorized to
be issued, or a statement of the existence of such preferences, powers,
qualifications and rights, and a statement that the Corporation will furnish a
copy thereof to the holder of such certificate upon written request and without
charge.

         SECTION 2. Transfer of Shares. The shares of the stock of the
                    ------------------  
Corporation shall be transferred on the books of the Corporation by the holder
thereof in person or by his or her attorney lawfully constituted, upon surrender
for cancellation of certificates for the same number of shares, with an
assignment and power of transfer endorsed thereon or attached thereto, duly
executed, with such proof or guaranty of the authenticity of the signature as
the Corporation or its agents may reasonably require. The Corporation shall be
entitled to treat the holder of record of any share or shares of stock as the
holder in fact thereof and accordingly shall not be bound to recognize any
equitable or other claim to or interest in such share or shares on the part of
any other person whether or not it shall have express or other notice thereof,
save as expressly provided by law or by the Certificate of Incorporation. It
shall be the duty of each stockholder to notify the Corporation of his or her
post office address.

         SECTION 3. Closing of Transfer Books. The stock transfer books of the
                    -------------------------
Corporation may, if deemed appropriate by the Board of Directors, be closed for
such length of time not exceeding fifty (50) days as the Board may determine,
preceding the date of any meeting of stockholders or the date for the payment of
any dividend or the date for the allotment of rights or the date when any
issuance, change, conversion or exchange of capital stock shall go into effect,
during which time no transfer of stock on the books of the Corporation may be
made.

         SECTION 4. Fixing Date for Determination of Stockholders of Record. In
                    -------------------------------------------------------
order that the Corporation may determine the stockholders entitled to notice of
or to vote at any meeting of stockholders or any adjournment thereof, or to
express consent to corporate action in writing without a meeting, or entitled to
receive payment of any dividend or other distribution or allotment of any
rights, or entitled to exercise any rights in respect of any change, conversion
or exchange 
<PAGE>
 
By-laws of American Tower Corporation
A Delaware Corporation
Page 14

of stock or for the purpose of any other lawful action, the Board of Directors
may fix a record date, which record date shall not precede the date upon which
the resolution fixing the record date is adopted by the Board of directors and
which record date: (a) in the case of determination of stockholders entitled to
vote at any meeting of stockholders or adjournment thereof, shall, unless
otherwise required by law, the Certificate of Incorporation or otherwise, not be
more than sixty (60) nor less than ten (10) days before the date of such
meeting; (b) in the case of determination of stockholders entitled to express
consent to corporate action in writing without a meeting, shall, unless
otherwise required by law, the Certificate of Incorporation or otherwise, not be
more than ten (10) days from the date upon which the resolution fixing the
record date is adopted by the Board of Directors; and (c) in the case of any
other action, shall not be more than sixty (60) days prior to such other action.
If no record date is fixed: (a) the record date for determining stockholders
entitled to notice of or to vote at a meeting of stockholders shall be at the
close of business on the day next preceding the day on which notice is given,
or, if notice is waived, at the close of business on the day next preceding the
day on which the meeting is held; (b) the record date for determining
stockholders entitled to express consent to corporate action in writing without
a meeting when no prior action of the Board of Directors is required by law,
shall be the first date on which a signed written consent setting forth the
action taken or proposed to be taken is delivered to the Corporation in
accordance with applicable law, or, if prior action by the Board of Directors is
required by law, shall be at the close of business on the day on which the Board
of Directors adopts the resolution taking such prior action; and (c) the record
date for determining stockholders for any other purpose shall be at the close of
business on the day on which the Board of Directors adopts the resolution
relating thereto. A determination of stockholders of record entitled to notice
of or to vote at a meeting of stockholders shall apply to any adjournment of the
meeting; provided, however, that the Board of Directors may fix a new record
date for the adjourned meeting.

          SECTION 5. Lost or Destroyed Certificates. In case of the loss or
                     ------------------------------
destruction of any certificate of stock, a new certificate may be issued under
the following conditions:

          (a)  The owner of said certificate shall file with the Secretary or
               any Assistant Secretary of the Corporation an affidavit giving
               the facts in relation to the ownership, and in relation to the
               loss or destruction of said certificate, stating its number and
               the number of shares represented thereby; such affidavit shall be
               in such form and contain such statements as shall satisfy the
               President, any Executive Vice President, Vice President, the
               Secretary, any Assistant Secretary, the Treasurer or any
               Assistant Treasurer, that said certificate has been accidentally
               destroyed or lost, and that a new certificate ought to be issued
               in lieu thereof. Upon being so satisfied, any such officer may
               require such owner to furnish the Corporation a bond in such
               penal sum and in such form as he or she may deem advisable, and
               with a surety or sureties approved by him or her, to indemnify
               and save harmless the Corporation from any claim, loss, damage or
               liability which may be occasioned by the issuance of a new
               certificate in lieu thereof. Upon such bond being so filed, if so
               required, a new certificate for the same number of shares shall
<PAGE>
 
By-laws of American Tower Corporation
A Delaware Corporation
Page 15

               be issued to the owner of the certificate so lost or destroyed;
               and the transfer agent and registrar, if any, of stock shall
               countersign and register such new certificate upon receipt of a
               written order signed by any such officer, and thereupon the
               Corporation will save harmless said transfer agent and registrar
               in the premises. In case of the surrender of the original
               certificate, in lieu of which a new certificate has been issued,
               or the surrender of such new certificate, for cancellation, the
               bond of indemnity given as a condition of the issue of such new
               certificate may be surrendered; or

         (b)   The Board of Directors of the Corporation may by resolution
               authorize and direct any transfer agent or registrar of stock of
               the Corporation to issue and register respectively from time to
               time without further action or approval by or on behalf of the
               Corporation new certificates of stock to replace certificates
               reported lost, stolen or destroyed upon receipt of an affidavit
               of loss and bond of indemnity in form and amount and with surety
               satisfactory to such transfer agent or registrar in each instance
               or upon such terms and conditions as the Board of Directors may
               determine.

         SECTION 6. Uncertificated Shares. The Board of Directors of the
                    ---------------------
Corporation may by resolution provide that one or more of any or all classes or
series of the stock of the Corporation shall be uncertificated shares, subject
to the provisions of Section 158 of the Delaware General Corporation Law.


                                 ARTICLE VIII
                                 ------------ 

                             EXECUTION OF DOCUMENTS

         SECTION 1. Execution of Checks, Notes, etc. All checks and drafts on
                    -------------------------------
the Corporation's bank accounts and all bills of exchange and promissory notes,
and all acceptances, obligations and other instruments for the payment of money,
shall be signed by such officer or officers, or agent or agents, as shall be
thereunto authorized from time to time by the Board of Directors, which may in
its discretion authorize any such signatures to be facsimile.

         SECTION 2. Execution of Contracts, Assignments, etc. Unless the Board
                    ----------------------------------------
of Directors shall have otherwise provided generally or in a specific instance,
all contracts, agreements, endorsements, assignments, transfers, stock powers,
or other instruments shall be signed by the President, any Executive Vice
President, any Vice President, the Secretary, any Assistant Secretary, the
Treasurer or any Assistant Treasurer. The Board of Directors may, however, in
its discretion, require any or all such instruments to be signed by any two or
more of such officers, or may permit any or all of such instruments to be signed
by such other officer or officers, agent or agents, as it shall be thereunto
authorize from time to time.
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By-laws of American Tower Corporation
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Page 16

         SECTION 3. Execution of Proxies. The President, any Executive Vice
                    --------------------  
President or any Vice President, and the Secretary, the Treasurer, any Assistant
Secretary or any Assistant Treasurer, or any other officer designated by the
Board of Directors, may sign on behalf of the Corporation proxies to vote upon
shares of stock of other companies standing in the name of the Corporation.


                                  ARTICLE IX
                                  ----------

                              INSPECTION OF BOOKS

         The Board of Directors shall determine from time to time whether, and
if allowed, to what extent and at what time and places and under what conditions
and regulations, the accounts and books of the Corporation (except such as may
by law be specifically open to inspection) or any of them, shall be open to the
inspection of the stockholders, and no stockholder shall have any right to
inspect any account or book or document of the Corporation, except as conferred
by the laws of the State of Delaware, unless and until authorized so to do by
resolution of the Board of Directors or of the stockholders of the Corporation.

                                   ARTICLE X
                                   ---------

                                  FISCAL YEAR

         The fiscal year of the Corporation shall be determined from time to
time by vote of the Board of Directors.


                                  ARTICLE XI
                                  ----------

                                  AMENDMENTS

         These By-Laws may be altered, amended, changed or repealed and new
By-Laws adopted by the stockholders or, to the extent provided in the
Certificate of Incorporation, by the Board of Directors, in either case at any
meeting called for that purpose at which a quorum shall be present. Any by-law,
whether made, altered, amended, changed or repealed by the stockholders or the
Board of Directors may be repealed, amended, changed, further amended, changed,
repealed or reinstated, as the case may be, either by the stockholders or by the
Board of Directors, as herein provided; except that this Article may be altered,
amended, changed or repealed only by vote of the stockholders.


                                  ARTICLE XII
                                  -----------

                                INDEMNIFICATION
<PAGE>
 
By-laws of American Tower Corporation
A Delaware Corporation
Page 17

         SECTION 1. Indemnification. (a) The Corporation shall indemnify and
                    ---------------
hold harmless, to the fullest extent permitted by applicable law as it presently
exists or may hereafter be amended, any person who was or is a party or is
threatened to be made a party or is otherwise involved in any threatened,
pending or completed action, suit or proceeding, whether civil, criminal,
administrative or investigative (other than an action by or in the right of the
Corporation) by reason of the fact that he, or a person for whom he is the legal
representative, is or was a director, officer, employee or agent of the
Corporation, or is or was serving at the request of the Corporation as a
director, officer, partner, member, trustee, employee or agent of another
corporation, partnership, joint venture, limited liability company, trust or
other enterprise or non-profit entity against all liability, losses, expenses
(including attorneys' fees), judgments, fines, and amounts paid in settlement
actually and reasonably incurred by him in connection with such action, suit or
proceeding if he acted in good faith and in a manner he reasonably believed to
be in or not opposed to the best interest of the Corporation, and, with respect
to any criminal action or proceeding, had no reasonable cause to believe his
conduct was unlawful. The termination of any action, suit or proceeding by
judgment, order, settlement, conviction, or upon a plea of nolo contendere or
its equivalent, shall not, of itself, create a presumption that the person did
not act in good faith and in a manner which he reasonably believed to be in or
not opposed to the best interest of the Corporation, and, with respect to any
criminal action or proceeding, had reasonable cause to believe that his conduct
was unlawful.

         (b) The Corporation shall indemnify any person who was or is a party or
is threatened to be made a party to any threatened, pending or completed action
or suit by or in the right of the Corporation to procure a judgment in its favor
by reason of the fact that he is or was a director, officer, employee or agent
of the Corporation, or is or was serving at the request of the Corporation as a
director, officer, partner, member, trustee, employee or agent of another
corporation, partnership, joint venture, limited liability company, trust or
other enterprise or non-profit entity against expenses (including attorneys'
fees) actually and reasonably incurred by him in connection with the defense or
settlement of such action or suit if he acted in good faith and in a manner he
reasonably believed to be in or not opposed to the best interests of the
Corporation; except that no indemnification shall be made in respect of any
claim, issue or matter as to which such person shall have been adjudged to be
liable for negligence or misconduct in the performance of his duty to the
Corporation unless and only to the extent that the Court of Chancery of the
State of Delaware or the court in which such action or suit was brought shall
determine upon application that despite the adjudication of liability but in
view of all the circumstances of the case, such person is fairly and reasonably
entitled to indemnity for such expenses which the Court of Chancery of the State
of Delaware or such other court shall deem proper.

         (c) To the extent that any person referred to in paragraphs (a) or (b)
has been successful on the merits or otherwise in defense of any action, suit or
proceeding referred to therein, or in defense of any claim, issue or matter
therein, he or she shall be indemnified against expenses (including attorneys'
fees) actually and reasonably incurred by him or her in connection therewith.
<PAGE>
 
By-laws of American Tower Corporation
A Delaware Corporation
Page 18

         SECTION 2. Authorization. Any indemnification under Section 1 of this
                    -------------
Article (unless ordered by a court) shall be made by the Corporation only as
authorized in the specific case upon a determination that indemnification of the
director, officer, partner, member, trustee, employee or agent is proper in the
circumstances because such person has met the applicable standard of conduct set
forth in Section 1 of this Article. Such determination shall be made: (a) by the
Board of Directors by a majority vote of a quorum consisting of directors who
were not parties to such action, suit or proceeding, or (b) if such a quorum is
not obtainable, or, even if obtainable, a quorum of disinterested directors so
directs, by independent legal counsel in written opinion, or (c) by the
stockholders.

         SECTION 3. Expense Advance. Expenses (including attorneys' fees)
                    --------------- 
incurred by an officer or director of the Corporation in defending any civil,
criminal, administrative or investigative action, suit or proceeding may be paid
by the Corporation in advance of the final disposition of such action, suit or
proceeding as authorized by the Board of Directors in the manner provided in
Section 2 of this Article upon receipt of an undertaking by or on behalf of such
officer or director to repay such amount, unless it shall ultimately be
determined that such person is entitled to be indemnified by the Corporation as
authorized in this Article. Such expenses (including attorneys' fees) incurred
by other employees or agents of the Corporation may be so paid upon such terms
and conditions, if any, as the Board of Directors deems appropriate.

         SECTION 4. Nonexclusivity. The indemnification and advancement of
                    --------------
expenses provided by, or granted pursuant to, the other Sections of this Article
shall not be deemed exclusive of any other rights to which those seeking
indemnification or advancement of expenses may be entitled under any statute,
by-law, agreement, vote of stockholders or disinterested directors or otherwise,
both as to action in an official capacity and as to action in another capacity
while holding such office, and shall continue as to a person who has ceased to
be a director, officer, partner, member, trustee, employee or agent and shall
inure to the benefit of the heirs, executors and administrators of such a
person.

         SECTION 5. Insurance. The Corporation shall have power to purchase and
                    ---------
maintain insurance on behalf of any person who is or was a director, officer,
employee or agent of the Corporation, or is or was serving at the request of the
Corporation as a director, officer, partner, member, trustee, employee or agent
of another corporation, partnership, joint venture, limited liability company,
trust or other enterprise or non-profit entity against any liability asserted
against and incurred by him or her in any such capacity, or arising out of his
or her status as such, whether or not the Corporation would have the power to
indemnify such person against such liability under the provisions of this
Article or Section 145 of the Delaware General Corporation Law.

         SECTION 6. "The Corporation". For the purposes of this Article,
                     ---------------
references to "the Corporation" shall include the resulting corporation and, to
the extent that the Board of Directors of the resulting corporation so decides,
all constituent corporations (including any constituent of a constituent)
absorbed in a consolidation or merger which, if its separate existence had
continued, 
<PAGE>
 
By-laws of American Tower Corporation
A Delaware Corporation
Page 19

would have had power and authority to indemnify its directors, officers and
employees or agents so that any person who is or was a director, officer,
employee or agent of such a constituent corporation or is or was serving at the
request of such constituent corporation as director, officer, partner, member,
trustee, employee or agent of another corporation, partnership, joint venture,
limited liability company, trust or other enterprise or non-profit entity shall
stand in the same position under the provisions of this Article with respect to
the resulting or surviving corporation if its separate existence had continued.

          SECTION 7. Other Indemnification. The Corporation's obligation, if
                     ---------------------  
any, to indemnify any person who was or is serving at its request as a director,
trustee, partner, officer, employee or agent of another corporation,
partnership, joint venture, trust or other enterprise or non-profit entity shall
be reduced by any amount such person may collect as indemnification from such
other corporation, partnership, joint venture, trust or other enterprise or
non-profit entity or from insurance.

         SECTION 8. Other Definitions. For purposes of this Article, references
                    -----------------
to "other enterprises" shall include employee benefit plans; references to
"fines" shall include any excise taxes assessed on a person with respect to an
employee benefit plan; and references to "serving at the request of the
Corporation" shall include any service as a director, trustee, officer, employee
or agent of the Corporation which imposes duties on, or involves services by,
such director, trustee, officer, employee, or agent with respect to an employee
benefit plan, its participants, or beneficiaries; and a person who acted in good
faith and in a manner he or she reasonably believed to be in the interest of the
participants and beneficiaries of an employee benefit plan shall be deemed to
have acted in a manner "not opposed to the best interests of the Corporation" as
referred to in this Article.

         SECTION 9. Continuation of Indemnification. The indemnification and
                    -------------------------------
advancement of expenses provided by, or granted pursuant to, this Article shall,
unless otherwise provided when authorized or ratified, continue as to a person
who has ceased to be a director, trustee, partner, officer, employee or agent
and shall inure to the benefit of the heirs, executors and administrators of
such a person.

         SECTION 10. Amendment or Repeal. Neither the amendment nor repeal of
                     -------------------
this Article nor the adoption of any provision of these By-Laws inconsistent
with this Article shall reduce, eliminate or adversely affect any right or
protection hereunder of any person in respect of any act or omission occurring
prior to the effectiveness of such amendment, repeal or adoption.


<PAGE>

                                                                         EXHIBIT
                                                                          10.13
 
                           AMERICAN TOWER CORPORATION


                            STOCK PURCHASE AGREEMENT


     THIS AGREEMENT (this "Agreement")  is made as of February 4, 1999 by and
between American Tower Corporation, a Delaware corporation ("ATC") and Credit
Suisse First Boston Corporation ("CSFB").

     WHEREAS, CSFB desires to purchase, and ATC is willing to sell 500,000
shares of Class A Common Stock, par value $.01 per share,  of ATC (the "ATC
Common Stock"), all on the terms and subject to the conditions of this
Agreement;  and

     WHEREAS, ATC and CSFB wish to provide for the terms and conditions of the
purchase and sale of the ATC Common Stock and certain related matters;

     NOW, THEREFORE, for and in consideration of the mutual covenants and
agreements herein contained, and other valuable consideration, the receipt and
adequacy whereof are hereby acknowledged, the parties hereto, intending to be
legally bound, do hereby covenant and agree as follows:

<PAGE>
 
     SECTION 1.  Authorization and Closing.
                 ------------------------- 

     (a) Authorization of the Securities.  ATC has authorized the issue and sale
         -------------------------------                                        
to CSFB, and CSFB has agreed to purchase 500,000 shares of ATC Common Stock
(collectively, the "Subject Shares") at a purchase price equal to $26.3125 per
share.

     (b) Purchase and Sale of the Subject Shares.  At the Closing, subject to
         ---------------------------------------                             
the terms and conditions set forth herein, ATC shall issue to CSFB, and CSFB
shall acquire from ATC, the Subject Shares set forth in Section 1(a).  CSFB will
make payment in the form of a wire transfer of immediately available funds or
bank cashier's or certified check; and

     (c) The Closing.  The closing (the "Closing") of the issue and acquisition
         -----------                                                           
of the Subject Shares shall take place at the offices of Sullivan & Cromwell,
New York, New York on February 9, 1999 at 10:00 a.m. or at such other date and
place as may be mutually agreeable to ATC and CSFB.  Any wire transfer of funds
shall be made to such bank account in the United States as shall have been
designated in writing by ATC a reasonable time prior to the Closing.

     SECTION 2.  Conditions of CSFB's Obligation.  The obligation of CSFB to
                 -------------------------------                            
acquire the Subject Shares to be purchased by CSFB at the Closing is subject to
the satisfaction (or waiver in writing by CSFB) as of the Closing of the
following conditions:

     (a) Representations and Warranties; Covenants.  The representations and
         -----------------------------------------                          
warranties contained in Section 4 shall be true and correct in all material
respects at and as of the Closing as though then made, except to the extent
of changes caused by the transactions expressly contemplated herein, and
ATC shall have performed in all material respects all of the covenants
required to be performed by it hereunder prior to the Closing.

     (b) Registration Rights Agreement.  ATC shall have executed and delivered
         -----------------------------                                        
to CSFB an agreement substantially in the form of Exhibit A attached hereto
and made a part hereof (the "Registration Rights Agreement").

     (c) Legal Opinion.  ATC shall have delivered to CSFB an opinion of
         -------------                                                 
Sullivan & Worcester LLP, counsel for ATC, as to the due organizations and
corporate existence of ATC, the due authorization, execution, delivery and
binding effect of this Agreement, and the due authorization and valid
issuance of the Subject Shares and their fully paid and nonassessable
status.

     (d) Proceedings.  All corporate and other proceedings taken or
         -----------                                               
required to be taken by ATC in connection with the transactions
contemplated hereby to be consummated at or prior to the Closing and all
documents incident thereto shall be reasonably satisfactory in form and
substance to CSFB and their counsel.

     (e) Closing Documents.  ATC shall have delivered to CSFB such documents,
         -----------------                                                   
instruments and certificates relating to the transactions contemplated by this
Agreement as CSFB or its counsel may reasonably request.
     
     SECTION 3.  Conditions of ATC's Obligation.  The obligation of ATC to issue
                 ------------------------------                                 
and sell the Subject Shares to CSFB at the Closing is subject to the
satisfaction (or waiver in writing by ATC) as of the Closing of the following
conditions:

                                      -2-
<PAGE>
 
     (a) Representations and Warranties; Covenants.  The representations
         -----------------------------------------                      
and warranties of CSFB contained in Section 5 shall be true and correct in
all material respects at and as of the Closing as though then made, except
to the extent of changes caused by the transactions expressly contemplated
herein, and CSFB shall have performed in all material respects all of the
covenants required to be performed by him or it hereunder prior to the
Closing.

     (b) Proceedings.  All corporate and other proceedings taken or
         -----------                                               
required to be taken by CSFB in connection with the transactions
contemplated hereby to be consummated at or prior to the Closing and all
documents incident thereto shall be reasonably satisfactory in form and
substance to ATC and its counsel.

     (c) Closing Documents.  CSFB shall have delivered to ATC such
         -----------------                                        
documents, instruments and certificates relating to the transactions
contemplated by this Agreement as ATC or its counsel may reasonably
request.

     SECTION 4.  Representations and Warranties of ATC.  As a material
                      -------------------------------------                
inducement to CSFB to enter into this Agreement and purchase the Subject Shares,
ATC hereby makes the following representations and warranties to CSFB.

     (a) Organization and Corporate Power.  ATC and each of its subsidiaries is
         --------------------------------                                      
an entity duly organized, validly existing and in good standing under the laws
of its jurisdiction of organization and is qualified to do business in each
jurisdiction in which the failure so to qualify would reasonably be expected to
have a material adverse effect on the business, financial condition or results
of operation of ATC and its subsidiaries taken as a whole.  ATC and each of its
subsidiaries has all requisite corporate and other power and authority and all
material licenses, permits and authorizations necessary to own and operate its
properties, to carry on its businesses as now conducted and presently proposed
to be conducted and, in the case of ATC, to execute and deliver and consummate
the transactions contemplated by this Agreement.

     (b) Material Statements and Omissions; Absence of Events.  The
         ----------------------------------------------------      
information with respect to ATC included in the prospectus included in the
registration statement to be filed on or about February 8, 1999 heretofore
delivered by ATC to CSFB (the "ATC Prospectus") does not and will not
contain any untrue statement of a material fact and does not and will not
omit to state any material fact required to make any statement contained
herein or therein, in light of the circumstances under which they were
made, not misleading.  Since the date of the most recent financial
statements set forth in the ATC Prospectus, except to the extent described
in the ATC Prospectus, there has been no material adverse change in ATC.

     (c) Capital Stock and Related Matters.
         --------------------------------- 

     (i) The authorized and issued capital stock of ATC is as set forth in
the ATC Prospectus.  All of the outstanding shares of the ATC Common Stock
are, and all of the Subject Shares will, upon issuance pursuant to the
provisions of this Agreement, be, duly authorized, validly issued, fully
paid and nonassessable.

     (ii)  There are no statutory or, to the best of ATC's knowledge,
contractual stockholder preemptive rights or rights of refusal with respect
to the issuance of the Subject Shares.  ATC has not violated any applicable
federal or state securities laws in connection with the offer, sale or
issuance of any of its capital stock, and, based on the representations and
warranties of CSFB set 

                                      -3-
<PAGE>
 
forth in Section 5(g), the offer, sale and issuance of the Subject Shares
hereunder does not require registration under the Securities Act of 1933, as
amended (the "Securities Act") or any applicable state securities laws.

     (d) Authorization; No Breach.  The execution, delivery and performance of
         ------------------------                                             
this Agreement, the Registration Rights Agreement and all other agreements
contemplated hereby to which ATC is or will be a party have been duly authorized
by ATC.  This Agreement,  the Registration Rights Agreement and all other
agreements contemplated hereby each constitutes a valid and binding obligation
of ATC, enforceable in accordance with its terms, except as (i) the
enforceability thereof may be limited by bankruptcy, reorganization, insolvency,
moratorium, fraudulent conveyance or other laws of general applicability
affecting the enforcement of creditors' or secured parties' rights or debtors'
obligations generally and (ii) the availability of specific performance or other
equitable remedies may be limited by equitable principles of general
applicability (whether such matter is considered in a proceeding at law or in
equity).  The (x) execution and delivery by ATC of this Agreement and the
Registration Rights Agreement, (y) offering, sale and issuance of the Subject
Shares hereunder, and (z) fulfillment of and compliance with the respective
terms hereof and thereof by ATC, do not and shall not, except in respect of
clause (z) above, for filings and other actions to be performed upon the
occurrence of certain future events, as contemplated by the Registration Rights
Agreement, (i) conflict with or result in a breach of the terms, conditions or
provisions of, (ii) constitute a default under, (iii) result in the creation of
any lien, security interest, charge or encumbrance upon ATC's or any
subsidiary's capital stock or assets pursuant to, (iv) give any third party the
right to modify, terminate or accelerate any obligation under, (v) result in a
violation of, or (vi) require any authorization, consent, approval, exemption or
other action by or notice to any court or administrative or governmental body
pursuant to, the charter or by-laws or other organizational documents of ATC or
any subsidiary, or any law, statute, rule or regulation to which ATC or any
subsidiary is subject, or any contract, agreement, instrument, order, judgment
or decree to which ATC or any subsidiary is subject, which such authorization,
consent, approval, exemption, action or notice has not been obtained, except in
all cases for such exceptions as would not, individually or in the aggregate,
have a material adverse effect on the business, financial conditions or results
of operation of ATC and its subsidiaries taken as a whole.

     (e) Brokerage.  There are no claims for brokerage commissions, finders'
         ---------                                                          
fees or similar compensation in connection with the transactions contemplated by
this Agreement based on any arrangement or agreement binding upon ATC or any
subsidiary.  ATC shall pay, and hold CSFB harmless against, any liability, loss
or expense (including, without limitation, reasonable attorneys' fees and out-
of-pocket expenses) arising in connection with any such claim.

     (f) Governmental Consent, etc.  No permit, consent, approval or
         -------------------------                                  
authorization of, or declaration to or filing with, any governmental authority
is required in connection with the execution, delivery and performance by ATC of
this Agreement or the other agreements contemplated hereby, or the consummation
by ATC of any other transactions contemplated hereby or thereby, except as
expressly contemplated herein or therein or in the exhibits hereto or thereto.

     SECTION 5.  Representations and Warranties of each CSFB.  As a material
                 -------------------------------------------                
inducement to ATC to enter into this Agreement and issue and sell the Subject
Shares CSFB hereby makes the following representations and warranties to ATC.

                                      -4-
<PAGE>
 
     (a) Organization and Power.  CSFB is duly organized, validly existing and
         ----------------------                                               
in good standing under the laws of its jurisdiction of organization and has all
requisite corporate or other power and authority to execute and deliver and
consummate the transactions contemplated by this Agreement.

     (b) Authorization; No Breach.  The execution, delivery and performance of
         ------------------------                                             
this Agreement, the Registration Rights Agreement and all other agreements
contemplated hereby to which CSFB is or will be a party have been duly
authorized by CSFB.  This Agreement, the Registration Rights Agreement and all
other agreements contemplated hereby to which CSFB is or will be a party each
constitutes a valid and binding obligation of such CSFB, enforceable in
accordance with its terms, except as (i) the enforceability thereof may be
limited by bankruptcy, reorganization, insolvency, moratorium, fraudulent
conveyance or other laws of general applicability affecting the enforcement of
creditors' or secured parties' rights or debtors' obligations generally and (ii)
the availability of specific performance or other equitable remedies may be
limited by equitable principles of general applicability (whether such matter is
considered in a proceeding at law or in equity).  The (x) execution and delivery
by CSFB of this Agreement, the Registration Rights Agreement and all other
agreements contemplated hereby to which CSFB is or will be a party, and (y)
fulfillment of and compliance with the respective terms hereof and thereof by
CSFB, do not and shall not, except in respect of clause (y) above, for filings
and other actions to be performed upon the occurrence of certain future events,
as contemplated by the Registration Rights Agreement, (i) conflict with or
result in a breach of the terms, conditions or provisions of, (ii) constitute a
default under, (iii) result in the creation of any lien, security interest,
charge or encumbrance upon CSFB's assets pursuant to, (iv) give any third party
the right to modify, terminate or accelerate any obligation under, (v) result in
a violation of, or (vi) require any authorization, consent, approval, exemption
or other action by or notice to any court or administrative or governmental body
pursuant to, any law, statute, rule or regulation to which CSFB is subject, or
any contract, agreement, instrument, order, judgment or decree to which CSFB is
subject, which such authorization, consent, approval, exemption, action or
notice has not been obtained.

     (c) Brokerage.  There are no claims for brokerage commissions, finders'
         ---------                                                          
fees or similar compensation in connection with the transactions contemplated by
this Agreement based on any arrangement or agreement binding upon CSFB.  CSFB
shall pay and hold ATC harmless against any liability, loss or expense
(including, without limitation, reasonable attorneys' fees and out-of-pocket
expenses) arising in connection with any such claim.

     (d) Governmental Consent, etc.  No permit, consent, approval or
         -------------------------                                  
authorization of, or declaration to or filing with, any governmental authority
is required in connection with the execution, delivery and performance by CSFB
of this Agreement or the other agreements contemplated hereby, or the
consummation by CSFB of any other transactions contemplated hereby or thereby,
except as expressly contemplated herein or therein, in the exhibits hereto or
thereto or in the ATC Prospectus.

     (e) Investment Representation.  CSFB is an "accredited investor" as such
         -------------------------                                           
term is defined in Rule 501 of Regulation D ("Regulation D") promulgated under
the Securities Act.  The Subject Shares to be acquired by CSFB are being
acquired solely for the account of CSFB for purposes of investment and not with
a view to the sale, transfer or other distribution thereof, as those terms are
used in the Securities Act and the rules and regulations promulgated thereunder;
provided, however, that nothing contained herein shall prevent CSFB and
subsequent holders of Subject Shares from transferring such securities in
compliance with the applicable provisions of the 

                                      -5-
<PAGE>
 
Securities Act (including without limitation Rule 144 promulgated thereunder or
pursuant to registration) and applicable state securities laws. CSFB covenants
and agrees that it will not sell, assign, transfer or otherwise dispose of any
of the Subject Shares to be acquired by CSFB in violation of the Securities Act
or applicable state securities laws. Each certificate for the Subject Shares
shall be imprinted with a legend in substantially the following form:

          "THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT
          BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
          AMENDED. THE TRANSFER OF THE SECURITIES REPRESENTED BY THIS
          CERTIFICATE IS SUBJECT TO THE CONDITIONS SPECIFIED IN THE
          STOCK PURCHASE AGREEMENT, DATED AS OF FEBRUARY 4, 1999,
          BETWEEN THE ISSUER ("ATC") AND CREDIT SUISSE FIRST BOSTON
          CORPORATION, AND ATC RESERVES THE RIGHT TO REFUSE THE
          TRANSFER OF SUCH SECURITIES UNTIL SUCH CONDITIONS HAVE BEEN
          FULFILLED WITH RESPECT TO SUCH TRANSFER. A COPY OF SUCH
          CONDITIONS SHALL BE FURNISHED BY ATC TO THE HOLDER HEREOF
          UPON WRITTEN REQUEST AND WITHOUT CHARGE." THIS LEGEND SHALL
          EXPIRE AUTOMATICALLY, AND SHALL BE REMOVED, ON FEBRUARY 5,
          2001.

     SECTION 6.  Miscellaneous.
                 ------------- 

     (a) Termination.  This Agreement may be terminated with the mutual consent
         -----------                                                           
of CSFB and ATC.

     (b) Amendment.  This Agreement may be amended, from time to time, by the
         ---------                                                           
parties hereto at any time prior to the Closing Date but only by an instrument
in writing signed by the parties hereto or their respective successors or
assigns.

     (c) Waiver. At any time prior to the Closing Date, the parties may, either
         ------                                                                
generally or in a particular instance and either retrospectively or
prospectively, extend the time for the performance of any of the obligations or
other acts of the other, and waive compliance by the other with any of the
agreements, covenants, conditions or other provisions contained herein.  Any
such extension or waiver shall be valid only if set forth in an instrument in
writing signed by the party or parties to be bound thereby.

     (d) Expenses. CSFB agrees to pay the reasonable out-of-pocket expenses of
         --------                                                             
ATC incident to the negotiation, preparation, performance and enforcement of
this Agreement (including all reasonable fees and expenses of ATC's counsel,
accountants and other consultants, advisors and representatives for all
activities of such persons undertaken pursuant to this Agreement).

     (e) Notices.  All notices and other communications which by any provision
         -------                                                              
of this Agreement are required or permitted to be given shall be given in
writing and shall be (a) mailed by first-class or express mail, postage prepaid,
or by recognized courier service, (b) sent by telecopy or other form of rapid
transmission, confirmed by mailing (by first class or express mail, postage
prepaid, or by recognized courier service) written confirmation at substantially
the same time as such rapid transmission, or (c) personally delivered to the
receiving party (which if, other than an individual, shall be an officer or
other responsible party of the receiving party).  All such notices and
communications shall be mailed, sent or delivered as follows:

                                      -6-
<PAGE>
 
If to ATC:       116 Huntington Avenue
                 Boston, Massachusetts 02116
                 Attention:   Joseph L. Winn, Chief Financial Officer
                 Telecopier No.:  (617) 375-7575

with a copy to:  Sullivan & Worcester LLP
                 One Post Office Square
                 Boston, Massachusetts 02109
                 Attention:  Norman A. Bikales, Esq.
                 Telecopier No.:  (617) 338-2880; and

If to CSFB:      11 Madison Avenue
                 New York, New York  10010
                 Attention:  Kristin M. Allen, Managing Director
                 Telephone No.:  (212) 325-2459

with a copy to:  Sullivan & Cromwell
                 125 Broad Street
                 New York, New York 10004
                 Attention: John T. Bostelman, Esq.
                 Telecopier No.: (212) 558-3588

or to such other person(s), telex or facsimile number(s) or address(es) as the
party to receive any such communication or notice may have designated by written
notice to the other party.

     (f) Specific Performance; Other Rights and Remedies.  Each party recognizes
         -----------------------------------------------                        
and agrees that in the event the other party should refuse to perform any of its
obligations under this Agreement, the remedy at law would be inadequate and
agrees that for breach of such provisions, each party shall, in addition to such
other remedies as may be available to it at law or in equity, be entitled to
injunctive relief and to enforce its rights by an action for specific
performance to the extent permitted by applicable law.  Each party hereby waives
any requirement for security or the posting of any bond or other surety in
connection with any temporary or permanent award of injunctive, mandatory or
other equitable relief. Nothing herein contained shall be construed as
prohibiting each party from pursuing any other remedies available to it under
applicable law or pursuant to the provisions of this Agreement for such breach
or threatened breach, including without limitation the recovery of damages.

     (g) Survival of Representations, Warranties, Covenants and Agreements.  All
         -----------------------------------------------------------------      
of the representations, warranties, covenants and agreements set forth in this
Agreement shall survive the Closing.

     (h) Severability.  If any term or provision of this Agreement shall be held
         ------------                                                           
or deemed to be, or shall in fact be, invalid, inoperative, illegal or
unenforceable as applied to any particular case in any jurisdiction or
jurisdictions, or in all jurisdictions or in all cases, because of the
conflicting of any provision with any constitution or statute or rule of public
policy or for any other reason, such circumstance shall not have the effect of
rendering the provision or provisions in question invalid, inoperative, illegal
or unenforceable in any other jurisdiction or in any other case or circumstance
or of rendering any other provision or provisions herein contained invalid,
inoperative, illegal or unenforceable to the extent that such other provisions
are not themselves actually in conflict with such constitution, statute or rule
of public policy, but this Agreement shall be reformed and construed in any such
jurisdiction or case as if such invalid, inoperative, illegal or unenforceable
provision had never been contained herein and such provision reformed 

                                      -7-
<PAGE>
 
so that it would be valid, operative and enforceable to the maximum extent
permitted in such jurisdiction or in such case. Notwithstanding the foregoing,
in the event of any such determination the effect of which is to affect
materially and adversely either CSFB or ATC, the parties shall negotiate in good
faith to modify this Agreement so as to effect the original intent of the
parties as closely as possible to the fullest extent permitted by applicable law
in an acceptable manner to the end that the intent and purpose of this Agreement
is fulfilled and consummated to the maximum extent possible.

     (i) Counterparts.  This Agreement may be executed in several counterparts,
         ------------                                                          
each of which shall be deemed an original, but all of which together shall
constitute one and the same instrument, binding upon all of the parties.  In
pleading or proving any provision of this Agreement, it shall not be necessary
to produce more than one of such counterparts.

     (j) Section Headings.  The headings contained in this Agreement are for
         ----------------                                                   
reference purposes only and shall not in any way affect the meaning or
interpretation of this Agreement.

     (k) Governing Law.  The validity, interpretation, construction and
         -------------                                                 
performance of this Agreement shall be governed by, and construed in accordance
with, the applicable laws of the United States of America and the laws of the
Commonwealth of Massachusetts applicable to contracts made and performed in such
State and, in any event, without giving effect to any choice or conflict of laws
provision or rule that would cause the application of domestic substantive laws
of any other jurisdiction, except to the extent the corporate laws of the State
of Delaware are applicable.  Anything in this Agreement to the contrary
notwithstanding, in the event of any dispute between the parties which results
in a legal action, litigation or other proceeding, the prevailing party shall be
entitled to receive from the non-prevailing party reimbursement for reasonable
legal fees and expenses incurred by such prevailing party in such legal action,
litigation or other proceeding.

     (l) Further Acts.  Each party agrees that at any time, and from time to
         ------------                                                       
time, before and after the consummation of the transactions contemplated by this
Agreement, it will do all such things and execute and deliver all such other
agreements, instruments or other documents and other assurances, as the other
party or its counsel reasonably deems necessary or desirable in order to carry
out the terms and conditions of this Agreement and the transactions contemplated
hereby or to facilitate the enjoyment of any of the rights created hereby or to
be created hereunder.

     (m) Assignment.  This Agreement shall not be assignable by any party and
         ----------                                                          
any such assignment shall be null and void, except that it shall inure to the
benefit of and be binding upon any successor to each party by operation of law,
including by way of merger, consolidation or sale of all or substantially all of
its assets, and, in the case of CSFB, any person to whom CSFB shall have
transferred any of the Subject Shares not in violation of this Agreement.
Notwithstanding the foregoing, ATC may assign its rights and remedies hereunder
to any bank or other financial institution which has loaned funds or otherwise
extended credit to it; and CSFB may assign its rights and obligations under this
Agreement and the Registration Rights Agreement, and may assign the Subject
Shares, to an affiliate that agrees to be bound thereby.

     (n) Parties in Interest.  This Agreement shall be binding upon and inure
         -------------------                                                 
solely to the benefit of the parties and their permitted successors and assigns,
and nothing in this Agreement, express or implied, is intended to or shall
confer upon any person any right, benefit or remedy of any nature whatsoever
under or by reason of this Agreement, except as otherwise provided in 
Section 6(m).

     (o) Certain Definitions.  Terms defined in the singular shall have a
         -------------------                                             
comparable meaning when used in the plural, and vice versa, and the reference to
any gender shall be deemed to include all genders. 

                                      -8-
<PAGE>
 
References to "hereof," "herein" or similar terms are intended to refer to the
Agreement as a whole and not a particular section, and references to "this
Section" are intended to refer to the entire section or article and not a
particular subsection thereof.

     (p) Mutual Drafting.  This Agreement is the result of the joint efforts of
         ---------------                                                       
ATC and CSFB, and each provision hereof has been subject to the mutual
consultation, negotiation and agreement of the parties and there shall be no
construction against either party based on any presumption of that party's
involvement in the drafting thereof.  Each of the parties is a sophisticated
legal entity or individual that was advised by experienced counsel and, to the
extent it deemed necessary, other advisors in connection with this Agreement.


                    SIGNATURES APPEAR ON THE FOLLOWING PAGE

                                      -9-
<PAGE>
 
     IN WITNESS WHEREOF, each of the parties hereto had caused this Agreement to
be duly executed and delivered as of the day and year first above written.


                              American Tower Corporation
 
 
                              By: 
                                  ----------------------------------------
                              Name:  Steven B. Dodge
                              Title: President and Chief Executive Officer



                              Credit Suisse First Boston Corporation



                              By: 
                                  ----------------------------------------
                              Name:
                              Title:

                                      -10-

<PAGE>

                                                                         EXHIBIT
                                                                          10.14
 
                         REGISTRATION RIGHTS AGREEMENT

                                    between

                          AMERICAN TOWER CORPORATION

                                      and

                    CREDIT SUISSE FIRST BOSTON CORPORATION



                               February 4, 1999

<PAGE>
 
                               TABLE OF CONTENTS
<TABLE>
<S>                                                                      <C>
1.   Registration of Securities.......................................   1
     ---------------------------               

     (a)  Registration by ATC.........................................   1
          -------------------
     (b)  Registration at CSFB's Request..............................   2
          ------------------------------
     (c)  Registration Generally......................................   3
          ----------------------
     (d)  Restrictions on Registration................................   7
          ----------------------------
     (e)  Additional Restrictions on Registration.....................   8
          ---------------------------------------      
                                               
2.   Conditions to Registration.......................................   8
     --------------------------                
                                               
3.   Indemnification..................................................   9
     ---------------                           
                                               
     (a)  Indemnification by ATC......................................   9
          -----------------------              
     (b)  Indemnification by CSFB.....................................   9
          -----------------------              
     (c)  Procedure...................................................  10
          ---------                            
     (d)  Contribution................................................  11
          ------------
                                               
4.   Exchange Act Registration........................................  12
     -------------------------                                              
                                               
5.   Termination of Registration Obligations..........................  13
     ---------------------------------------                              
                                               
6.   Registration Rights of Others....................................  14
     -----------------------------      

7.   Mergers, etc.....................................................  14
     ------------      

8.   Annual and Quarterly Reports; Other Information..................  14
     -----------------------------------------------                        
                                                     
9.   Withdrawals......................................................  14
     -----------                                     
                                                     
10.  Definitions......................................................  14
     -----------                                     
                                                     
11.  Miscellaneous....................................................  18
     -------------

     (a)  Assignment; Successors and Assigns..........................  18
          ----------------------------------
     (b)  Specific Performance; Other Rights and Remedies.............  18
          -----------------------------------------------        
     (c)  Expenses....................................................  18
          --------
     (d)  Entire Agreement............................................  19
          ----------------
     (e)  Waivers; Amendments.........................................  19
          -------------------
     (f)  Notices.....................................................  19
          -------
     (g)  Severability................................................  19
          ------------
     (h)  Counterparts................................................  20
          ------------
     (i)  Section Headings............................................  20
          ----------------
     (j)  Governing Law...............................................  20
          -------------
     (k)  Further Acts................................................  20
          ------------
</TABLE>

<PAGE>
 
                         REGISTRATION RIGHTS AGREEMENT


     This Registration Rights Agreement (this "Agreement") is made and entered
into as of February 4, 1999, by and between American Tower Corporation, a
Delaware corporation ("ATC"), and Credit Suisse First Boston Corporation
("CSFB"), which has heretofore agreed to acquire or has acquired the Registrable
Securities.

     WHEREAS, ATC has entered into a Stock Purchase Agreement, dated as of
February 4, 1999, with CSFB (the "ATC Stock Purchase Agreement") relating to the
issue and sale of shares of Class A Common Stock of ATC (the "ATC Common
Stock"), and it is a condition of the obligation of CSFB to consummate the
transactions contemplated by the ATC Stock Purchase Agreement that ATC enter
into an agreement substantially in the form of this Agreement; and

     WHEREAS, ATC has entered into and may in the future enter into agreements
pursuant to which it has agreed or will have agreed to issue securities the
holders of which have required or will require registration rights of a nature
set forth in this Agreement;

     NOW, THEREFORE, in consideration of the recitals, the mutual covenants and
agreements herein contained, and other valuable consideration, the receipt,
adequacy and sufficiency of which are hereby acknowledged, the parties hereto,
intending to be legally bound, do hereby covenant and agree as follows:
 
     1.   Registration of Securities.
          ---------------------------

     (a) Registration by ATC.  If at any time or from time to time ATC shall
         -------------------                                                
propose to file on its behalf or on behalf of any of its security holders a
registration statement under the Securities Act with respect to any class of
Common Stock, except in connection with an Excluded Offering, ATC shall, except
to the extent not required to do so pursuant to the provisions of Section 1(d)
or 1(e), in each case:

          (i) promptly give written notice to each Stockholder at least thirty
     (30) days (or such shorter period as ATC deems reasonable under the
     circumstances) before the anticipated filing date. Such notice shall
     include the anticipated offering price or range thereof and the plan of
     distribution;

          (ii) include in such registration (and any related qualification under
     blue sky or other state securities laws), and, at the request of a
     Stockholder, in any underwriting involved therein, all Registrable
     Securities specified in a written request or requests, made within ten (10)
     business days after such written notice from ATC, by any Stockholder; and

          (iii) use its reasonable business efforts to cause the managing
     underwriter or underwriters of any proposed underwritten offering of ATC
     Common Stock to permit the Registrable Securities requested to be included
     in the Registration Statement for such offering on the same terms and
     conditions as the ATC Common Stock included therein.  Notwithstanding the
     foregoing, if the managing underwriters of such offering deliver a written
     opinion to the holders of such Registrable Securities that marketing
     considerations require a limitation on the Registrable Securities included
     in any Registration Statement filed under this Section, then, subject to
     the advice of said managing underwriter or underwriters as to the size and
     composition of the offering, and subject to the provisions of Section 1(d),
     such limitation will be imposed pro rata (based upon the 

                                      -1-
<PAGE>
 
     relative proposed public offering price of the Registrable Securities
     proposed to be included) among all holders of Registrable Securities who
     requested inclusion in the registration pursuant to this Section. For
     purposes of this clause (iii), "Registrable Securities" shall include
     Registrable Securities as defined under the 1998 Registration Rights
     Agreement (as defined below).

     If any Stockholder desires to have Registrable Securities registered under
this Section, it shall be required so to advise ATC in writing within ten (10)
business days after the date of ATC's notice, setting forth the number or amount
of Registrable Securities for which registration is so requested.  Neither the
delivery of the notice by ATC nor of the request by any Stockholders shall in
any way obligate ATC to file a Registration Statement and, notwithstanding such
filing, ATC may, at any time prior to the effective date thereof, determine not
to offer the securities to which the registration statement relates without
liability to any of the Stockholders.  No registration of Registrable Securities
effected under this Section shall relieve ATC of its obligation to effect
registration of Registrable Securities upon any request made pursuant to the
provisions of Section 1(b).

     Notwithstanding the foregoing, CSFB's rights under this Section 1(a) are
subject to the written consent of the selling stockholders under Section 1(b) of
the Registration Rights Agreement, dated as of January 22, 1998, among ATC and
the stockholders named therein (the "1998 Registration Rights Agreement") but
only to the extent a registration statement is prepared upon the request of such
selling stockholders.

     (b) Registration at Stockholders' Request.  Upon the written request of any
         -------------------------------------                                  
Significant Stockholder requesting that ATC effect the registration under the
Securities Act of all or part of the Registrable Securities held by CSFB,
specifying the intended method or methods of disposition of such Registrable
Securities (which may include sales from time to time on a delayed basis), ATC
shall, except to the extent not required to do so pursuant to the provisions of
this Section 1(b) or Section 1(d) or (e), promptly (and in any event within five
(5) business days) give written notice of such requested registration to all
holders of Registrable Securities and thereupon will expeditiously prepare and,
within forty-five (45) days, use its reasonable business efforts to file under
the Securities Act a registration statement and effect the registration of:

          (i) the Registrable Securities which ATC has been so requested to
     register by CSFB, for disposition in accordance with the intended method of
     disposition stated in such request, and

          (ii) all other Registrable Securities which ATC has been requested to
     register by the holders of Registrable Securities by written request
     delivered to ATC within ten (10) business days after the giving of such
     notice by ATC (which request shall specify the intended method of
     disposition of such Registrable Securities).

     Each registration requested pursuant to this Section shall be effected by
the filing of a Registration Statement on Form S-1 (or such other form as the
Commission may from time to time require or permit in order to effectuate a
public offering of common stock of a company such as ATC and in a method of
disposition such as that proposed), unless the use of a different form has been
agreed upon in writing by holders of not less than a majority in value (based
upon the proposed public offering price) of the Registrable Securities as to
which registration has so been requested.  Notwithstanding the preceding
sentence, ATC need not so cause a Registration Statement so filed pursuant to
the provisions of this Section on a Form S-1 (or any successor form) to become
effective under the Securities Act on more than three (3) occasions; provided,

                                      -2-
<PAGE>
 
however, that there shall be no limit on the number of times ATC is obligated to
file Registration Statements on Form S-2 or S-3 (or any successor forms)
pursuant to the provisions of this Section (except as contemplated by the
definition of Significant Stockholder); and provided further, however, that any
registration of Registrable Securities requested by one or more Stockholders
pursuant to this Section which shall not have become and remained effective in
accordance with the provisions of Section 1(c) shall not be deemed to be a
registration for purposes of this Section.

     ATC shall not grant to any person the right to request ATC to register, nor
shall ATC include in any registration pursuant to this Section, any securities
other than the Registrable Securities or securities that are the subject of
registration rights granted prior to the date hereof, without the written
consent of holders of not less than a majority in value (based upon the proposed
public offering price) of the Registrable Securities as to which registration
has been so requested.

     Whenever registration requested by one or more Stockholders pursuant to
this Section is for an underwritten offering, only Registrable Securities which
are to be distributed by the underwriters designated by such Stockholders may be
included in such registration, without the written consent of holders of not
less than a majority in value (based upon the proposed public offering price) of
the Registrable Securities as to which registration has been so requested.  
If Stockholders holding not less than a majority in value of the Registrable
Securities (based upon the proposed public offering price) to be included in
such registration shall determine that the number of Registrable Securities
should be limited due to market conditions or otherwise, all holders of
Registrable Securities proposing to sell Registrable Securities in such
underwritten offering shall share pro rata in the number of Registrable
Securities to be excluded from such underwritten offering, such sharing to be
based on the value (based upon the proposed public offering price) of the
respective numbers of Registrable Securities as to which registration has been
requested by such Stockholders.

     (c) Registration Generally.  If and when ATC shall be required by the
         ----------------------                                           
provisions of this Section to effect the registration of Registrable Securities
under the Securities Act, ATC will use its reasonable business efforts to effect
such registration to permit the sale of such Registrable Securities in
accordance with the intended method or methods of disposition thereof, and
pursuant thereto it will, subject to the provisions of Section 1(d) and 1(e), as
expeditiously as possible:

          (i) before filing a Registration Statement or Prospectus or any
     amendments or supplements thereto, furnish to the holders of the
     Registrable Securities covered by such Registration Statement and the
     managing underwriters, if any, copies of all such documents proposed to be
     filed, which documents will be made available, on a timely basis, for
     review by such holders and underwriters, and their respective counsel, and
     ATC will not file any Registration Statement or amendment thereto or any
     Prospectus or any supplement thereto to which the holders of not less than
     a majority in value (based upon the proposed public offering price) of the
     Registrable Securities covered by such Registration Statement or the
     managing underwriters, if any, shall reasonably have objected;

          (ii) prepare and file with the Commission such amendments and post-
     effective amendments to any Registration Statement, and such supplements to
     the Prospectus, as may be reasonably requested by any holder of Registrable
     Securities included in such Registration Statement or any underwriter of
     Registrable Securities or as may be required by the rules, regulations or
     instructions applicable to the registration form utilized by ATC or by the
     Securities Act, the 

                                      -3-
<PAGE>
 
     Exchange Act or otherwise necessary to keep such Registration Statement
     effective for the applicable period and cause the Prospectus as so
     supplemented to be filed pursuant to Rule 424 under the Securities Act; and
     comply with the provisions of the Securities Act with respect to the
     disposition of all Registrable Securities covered by such Registration
     Statement during the applicable period in accordance with the intended
     method or methods of disposition by the holders of such Registrable
     Securities set forth in such Registration Statement or Prospectus as so
     supplemented;

          (ii) notify the selling holders of Registrable Securities and the
     managing underwriters, if any, promptly, and (if requested by any such
     Person) confirm such advice in writing,

               (A)  when the Prospectus or any supplement thereto or any
                    amendment or post-effective amendment to the Registration
                    Statement has been filed, and, with respect to the
                    Registration Statement or any post-effective amendment, when
                    the same has become effective,

               (B)  of any request by the Commission for amendments or post-
                    effective amendments to the Registration Statement or
                    supplements to the Prospectus or for additional information,

               (C)  of the issuance by the Commission of any stop order
                    suspending the effectiveness of the Registration Statement
                    or the initiation or threatening of any proceeding for such
                    purpose,

               (D)  if at any time the representations and warranties of ATC
                    contemplated by paragraph (xv) below cease to be true and
                    correct in all material respects,

               (E)  of the receipt by ATC of any notification with respect to
                    the suspension of the qualification of the Registrable
                    Securities for sale in any jurisdiction or the initiation or
                    threatening of any proceeding for such purpose, and

               (F)  of the existence of any Event which results in the
                    Registration Statement, the Prospectus or any document
                    incorporated therein by reference containing an untrue
                    statement of material fact or omitting to state a material
                    fact required to be stated therein or necessary to make the
                    statements therein, in light of the circumstances under
                    which they were made, not misleading;

          (iv) use its reasonable business efforts to obtain the withdrawal of
     any order suspending the effectiveness of the Registration Statement or any
     qualification referred to in paragraphs (iii)(C) and (iii)(E) at the
     earliest possible moment;

          (v) if requested by the managing underwriters or a holder of
     Registrable Securities being sold in connection with an underwritten
     offering, immediately incorporate in a Prospectus supplement or post-
     effective amendment to the Registration Statement such information as the
     managing underwriters or the holders of not less than a majority in value
     (based upon the proposed public offering price) of the Registrable
     Securities being sold reasonably a request to have included 

                                      -4-
<PAGE>
 
     therein relating to the plan of distribution with respect to such
     Registrable Securities, including, without limitation, information with
     respect to the amount of other Registrable Securities being sold to such
     underwriters, the purchase price being paid therefor by such underwriters
     and with respect to any other terms of the underwritten (or best efforts
     underwritten) offering of the Registrable Securities to be sold in such
     offering; and make all required filings of such Prospectus supplement or
     post-effective amendment promptly after being notified of the matters to be
     incorporated in such Prospectus supplement or post-effective amendment;

          (vi) at the request of any selling holder of Registrable Securities,
     furnish to such selling holder of Registrable Securities and each managing
     underwriter, if any, without charge, at least one signed copy of the
     Registration Statement and any post-effective amendment thereto, including
     financial statements and schedules, all documents incorporated therein by
     reference and all exhibits (including those incorporated by reference);

          (vii) deliver to each selling holder of Registrable Securities and the
     underwriters, if any, without charge, as many copies of the Registration
     Statement, each Prospectus (including each preliminary prospectus) and any
     amendment or supplement thereto (in each case including all exhibits,
     except that ATC shall not be obligated to furnish any such selling holder
     more than two copies of such exhibits other than incorporation documents),
     as such persons may reasonably request, together with such documents
     incorporated by reference in such Registration Statement or Prospectus, and
     such other documents as such selling holder or underwriter may reasonably
     request in order to facilitate the disposition of the Registrable
     Securities covered by such registration statement; ATC consents to the use
     of each Prospectus or any supplement thereto by each selling holder of
     Registrable Securities and the underwriters, if any, in connection with the
     offering and sale of the Registrable Securities covered by each
     Registration Statement or any amendment thereto;

          (viii) prior to any public offering of Registrable Securities, use its
     reasonable business efforts to register or qualify or cooperate with the
     selling holders of Registrable Securities, the underwriters, if any, and
     their respective counsel in connection with the registration or
     qualification of such Registrable Securities for offer and sale under the
     securities or blue sky laws of such jurisdictions as any selling holder or
     any underwriter reasonably requests in writing and do any and all other
     acts or things necessary or advisable to enable the disposition in such
     jurisdictions of the Registrable Securities covered by the Registration
     Statement; provided, however, that ATC will not be required to qualify
     generally to do business in any jurisdiction where it is not then so
     qualified or to take any action which would subject it to general service
     of process or general taxation in any such jurisdiction where it is not
     then so subject;

          (ix) cooperate with the selling holders of Registrable Securities and
     the underwriters, if any, to facilitate the timely preparation and delivery
     of certificates representing Registrable Securities to be sold and not
     bearing any restrictive legends; and enable such Registrable Securities to
     be in such denominations and registered in such names as the underwriters
     may reasonably request at least two (2) business days prior to any sale of
     Registrable Securities to the underwriters;

          (x) use its reasonable business efforts to cause the Registrable
     Securities covered by the Registration Statement to be registered with or
     approved by such other governmental agencies or authorities as may be
     necessary or advisable to enable the sellers thereof or the underwriters,
     if any, to consummate the disposition of such Registrable Securities;

                                      -5-
<PAGE>
 
          (xi) if any event contemplated by paragraph (iii) (F) above shall
     exist, prepare and furnish to such holders a post-effective amendment to
     the Registration Statement or supplement to the Prospectus or any document
     incorporated therein by reference or file any other required document so
     that, as thereafter delivered to the purchasers of the Registrable
     Securities, the Prospectus will not contain an untrue statement of a
     material fact or omit to state any material fact required to be stated
     therein or necessary to make the statements therein, in light of the
     circumstances under which they were made, not misleading;

          (xii) cause all Registrable Securities covered by the Registration
     Statement to be listed on each securities exchange or other trading market
     on which securities of the same class are then listed or traded or, if the
     Registrable Securities are not then listed on a securities exchange, and if
     the NASD is reasonably likely to permit the inclusion of the Registrable
     Securities on NASDAQ, use its reasonable business efforts to facilitate the
     inclusion of the Registrable Securities on NASDAQ;

          (xiii) not later than the effective date of the Registration
     Statement, provide a CUSIP number for all Registrable Securities and
     provide the applicable transfer agent or agents with printed certificates
     or instruments for the Registrable Securities which are in a form eligible
     for deposit with Depository Trust Company or other transferee and otherwise
     meeting the requirements of any securities exchange or other trading market
     on which such Registrable Securities are listed or traded;

          (xiv) enter into agreements (including underwriting agreements) and
     take all other appropriate actions in order to expedite or facilitate the
     disposition of such Registrable Securities and in such connection, whether
     or not an underwriting agreement is entered into and whether or not the
     offer and sale of the Registrable Securities is an underwritten offering:

               (A)  make such representations and warranties to the holders of
                    such Registrable Securities and the underwriters, if any, in
                    form, substance and scope, reasonably satisfactory to such
                    holders and underwriters, as are customarily made by issuers
                    to underwriters in primary underwritten offerings;

               (B)  obtain opinions and updates thereof of counsel which counsel
                    and opinions to ATC (in form, scope and substance) shall be
                    reasonably satisfactory to the underwriters, if any, and the
                    holders of not less than a majority in value (based on the
                    proposed public offering price) of the Registrable
                    Securities being sold, addressed to each selling holder and
                    the underwriters, if any, covering the matters customarily
                    covered in opinions requested in underwritten offerings and
                    such other matters as may be reasonably requested by such
                    holders and underwriters;

               (C)  obtain so-called "cold comfort" letters and updates thereof
                    from ATC's independent public accountants addressed to the
                    selling holders of Registrable Securities and the
                    underwriters, if any, such letters to be in customary form
                    and covering matters of the type customarily covered in
                    "cold comfort" letters to underwriters in connection with
                    primary

                                      -6-
<PAGE>
 
                    underwritten offerings and such other matters as may be
                    reasonably requested by such holders and underwriters;

               (D)  if an underwriting agreement is entered into, cause the same
                    to set forth in full the indemnification provisions and
                    procedures of Section 3 (or such other substantially similar
                    provisions and procedures as the underwriters shall
                    reasonably request) with respect to all parties to be
                    indemnified pursuant to said Section; and

               (E)  deliver such documents and certificates as may be reasonably
                    requested by the holders of not less than a majority in
                    value (based on the proposed public offering price) of the
                    Registrable Securities being sold or the underwriters, if
                    any, to evidence compliance with the provisions of this
                    Section and with any customary conditions contained in the
                    underwriting agreement or other agreement entered into by
                    ATC.

          The requirements of subparagraphs (B), (C) and (D) of this paragraph
          (xiv) shall be complied with at the effectiveness of such Registration
          Statement, each closing under any underwriting or similar agreement as
          and to the extent required thereunder and from time to time as may
          reasonably be requested by a majority in value (based on the proposed
          public offering price) of Registrable Securities being sold pursuant
          to such Registration Statement, all in a manner consistent with
          customary industry practice;

          (xv) make available to a representative of the holders of not less
     than a majority in value (based on the proposed public offering price) of
     the Registrable Securities, any underwriter participating in any
     disposition pursuant to such Registration Statement, and any attorney or
     accountant retained by such holders or underwriter, all  financial,
     corporate and other records and documents of ATC, and cause ATC's officers,
     directors and employees to supply all information reasonably requested by
     any such representatives, underwriter, attorney or accountant in connection
     with the registration, with respect to each at such time or times as the
     person requesting such information shall reasonably determine; provided,
     however, that any records, information or documents that are designated by
     ATC in writing as confidential shall be kept confidential by such persons
     unless disclosure of such records, information or documents is required by
     court or administrative order or applicable law or otherwise becomes public
     without breach of the provisions of this paragraph;

          (xvi) otherwise use its reasonable business efforts to comply with the
     Securities Act, the Exchange Act, all applicable rules and regulations of
     the Commission and all applicable state blue sky and other securities laws,
     rules and regulations, and make generally available to its security
     holders, earnings statements satisfying the provisions of Section 11(a) of
     the Securities Act, no later than thirty (30) days after the end of any 12-
     month period (or ninety (90) days if the end of such 12-month period
     coincides with the end of a fiscal quarter or fiscal year, respectively) of
     ATC (A) commencing at the end of any month in which Registrable Securities
     are sold to underwriters in an underwritten offering, or, if not sold to
     underwriters in such an offering, (B) beginning with the first month
     commencing after the effective date of the Registration Statement, which
     statements shall cover said 12-month periods;

                                      -7-
<PAGE>
 
          (xvii) cooperate and assist in any filings required to be made with
     the NASD and in the performance of any due diligence investigation by any
     underwriter (including any "qualified independent underwriter" that is
     required to be retained in accordance with the rules and regulations of the
     NASD);

          (xviii) promptly prior to the filing of any document which is to be
     incorporated by reference into the Registration Statement or the Prospectus
     (after the initial filing of the Registration Statement) provide copies of
     such document to the selling holders of Registrable Securities, the
     underwriters, if any, and their respective counsel, make ATC's
     representatives available for discussion of such document with such persons
     and make such changes in such document prior to the filing thereof as any
     such persons may reasonably request; and

          (xix) cooperate and assist in any filings required to be made with the
     FCC, including without limitation the obtaining of any consents of the FCC
     required in connection with any change in control of ATC.

     (d) Restrictions on Registration.  Anything in Section 1 to the contrary
notwithstanding, ATC shall not be required to register Registrable Securities on
behalf of any Stockholder to the following extent and subject to the following
conditions: in the case of any registration initially proposed to be filed
solely on behalf of ATC if, in the opinion of the managing underwriters of the
proposed public offering (a copy of which opinion shall have been furnished to
any Stockholder requesting registration (or each such holder if ATC has elected
not to notify the holders of Registrable Securities pursuant to the provisions
of Section 1(a) because it is not required to include any Registrable Securities
in such registration pursuant to the provisions of this Section)), such
registration (or such portion thereof as may be specified in such opinion) would
adversely affect the proposed public offering price or the plan of distribution
contemplated by the proposed ATC offering, in which event ATC shall (unless in
the opinion of such managing underwriters (a copy of which shall be similarly
furnished) to do so would materially and adversely affect the proposed public
offering price or such plan of distribution)) cause such Registration Statement
to remain in effect and to be phrased in such a manner so that the Stockholders
requesting registration thereunder may, during a period commencing not less than
sixty (60) days or more than ninety (90) days (or such other period as such
managing underwriters may approve as not so adversely affecting the proposed
public offering price or such plan of distribution) after the closing of the
sale to the underwriters pursuant to the original distribution thereunder, offer
and sell under such Registration Statement the Registrable Securities referred
to in the request of registration pursuant to this Section 1.

     (e) Additional Restrictions on Registration.  Anything in this Agreement to
         ---------------------------------------                                
the contrary notwithstanding, ATC shall not be required to file a registration
statement requested pursuant to this Section 1 if ATC has furnished, to the
Stockholders requesting a registration statement to be filed, a certificate
signed by the Chief Executive Officer or the Chief Financial Officer of ATC
stating that in the good faith judgment of the signer of such certificate the
filing of a registration statement would require the disclosure of material
information that ATC has a bona fide business purpose for preserving as
confidential and that is not then otherwise required to be disclosed; provided,
however, that ATC's obligation to use its reasonable business efforts to effect
a registration pursuant to this Section 1 may not be deferred pursuant to this
paragraph (e) for more than ninety (90) days from the date of receipt of a
written request from such Stockholders, and provided further, however, that ATC
shall not utilize this right more than once during any twelve (12) month period
unless the Stockholders requesting such registration have been afforded a
reasonable period (not less than ninety (90) days) during such twelve (12) month
period to effect such registration.

                                      -8-
<PAGE>
 
     2.   Conditions to Registration.
          -------------------------- 

     Each Stockholder's right to have Registrable Securities included in any
Registration Statement filed by ATC in accordance with the provisions of Section
1 shall be subject to the following conditions:

          (a) The holders on whose behalf such Registrable Securities are to be
     included shall be required to furnish ATC in a timely manner all
     information required by the applicable rules and regulations of the
     Commission concerning the proposed method of sale or other disposition of
     such Registrable Securities, the identity of and compensation to be paid to
     any proposed underwriters to be employed in connection therewith, and such
     other information as may be reasonably requested by ATC or its counsel
     properly to prepare and file such Registration Statement in accordance with
     applicable provisions of the Securities Act;

          (b) If any such holder  desires to sell and distribute Registrable
     Securities over a period of time, or from time to time, at then prevailing
     market prices, then any such holder shall execute and deliver to ATC such
     written undertakings as ATC and its counsel may reasonably request in order
     to assure full compliance with applicable provisions of the Securities Act
     and the Exchange Act;

          (c) In the case of any underwritten offering on behalf of the holders
     of Registrable Securities pursuant to the provisions of Section 1(b), the
     managing underwriters (other than CSFB or its affiliates) shall be subject
     to the approval of ATC, such approval not to be unreasonably withheld,
     delayed or conditioned;

          (d) In the case of any registration requested pursuant to the
     provisions of Section 1(a), the offering price for any Registrable
     Securities to be so registered shall be no less than for any securities of
     the same class then to be registered for sale for the account of ATC or
     other security holders, unless such Registrable Securities are to be
     offered from time to time based on the prevailing market price;

          (e) Upon receipt of any notice from ATC of the existence of any event
     of the nature referred to in paragraph (iii) of Section 1(c), such holder
     will forthwith discontinue disposition of Registrable Securities until such
     holder's receipt of the copies of the supplemented or amended Prospectus
     contemplated by such paragraph, or until it is advised in writing by ATC
     that the use of the Prospectus may be resumed, and has received copies of
     any additional or supplemental filings which are incorporated by reference
     in the Prospectus, and, if so directed by ATC, such holder will deliver to
     ATC all copies, other than permanent file copies then in such holder's
     possession, of the Prospectus covering such Registrable Securities current
     at the time of receipt of such notice;

          (f) In the event any filing with or consent of the FCC is required,
     cooperate and assist in any such filings, including without limitation
     providing all information required in obtaining any consents of the FCC
     required in connection with any change in control of ATC; and

          (g) The holders of Registrable Securities requesting registration
     shall pay all Registration Expenses in connection with such registration
     pursuant to the provisions of this Section.

                                      -9-
<PAGE>
 
          3.  Indemnification.
              --------------- 

          (a) Indemnification by ATC.  In the event of the registration of any
              ----------------------                                          
     Registrable Securities under the Securities Act pursuant to the provisions
     hereof, ATC will, to the extent permitted by Applicable Law, indemnify and
     hold harmless each Stockholder on whose behalf such Registrable Securities
     shall have been registered, its partners, trustees, advisory committee
     members, directors, officers, employees, representatives and agents, each
     underwriter, broker and dealer, if any, who participates in the offering or
     sale of such Registrable Securities, and each other Person, if any, who
     controls such Stockholder or any such underwriter, broker or dealer within
     the meaning of the Securities Act or the Exchange Act (each such person
     being hereinafter sometimes referred to as an "indemnified person"), from
     and against any Claims, joint or several, to which such indemnified person
     may become subject, including without limitation under the Securities Act,
     the Exchange Act or any state securities or blue sky law, insofar as such
     Claims arise out of or are based upon any untrue statement or alleged
     untrue statement of any material fact contained or incorporated by
     reference in any Registration Statement or Prospectus or any amendment or
     supplement thereto or in any preliminary prospectus, or any document
     incorporated by reference therein, or arise out of or based upon the
     omission or alleged omission to state therein a material fact required to
     be stated therein or necessary to make the statements therein, in light of
     the circumstances under which they were made, not misleading, and will
     reimburse each such indemnified person for any legal or any other expenses
     reasonably incurred by such indemnified person in connection with
     investigating or defending, settling or satisfying any such Claim;
     provided, however, that ATC will not be liable in any such case to the
     extent that any such Claim arises out of or is based upon an untrue
     statement or alleged untrue statement or omission or alleged omission made
     or incorporated by reference in the Registration Statement, Prospectus,
     amendment or supplement in reliance upon and in conformity with written
     information furnished to ATC by such indemnified person specifically
     stating that it is for use in preparation thereof.  Such indemnity shall
     remain in full force and effect regardless of any investigation made by or
     on behalf of such indemnified person and shall survive the transfer of such
     Registrable Securities by such Stockholder.

          (b) Indemnification by Holders of Registrable Securities.  In the
              ----------------------------------------------------         
     event of the registration of any Registrable Securities under the
     Securities Act pursuant to the provisions hereof, each Stockholder on whose
     behalf such Registrable Securities shall have been registered will, to the
     extent permitted by Applicable Law, severally but not jointly, indemnify
     and hold harmless, ATC, each director of ATC, each officer of ATC who signs
     the registration statement, each underwriter, broker and dealer, if any,
     who participates in the offering and sale of such Registrable Securities
     and each other Person, if any, who controls ATC or any such underwriter,
     broker or dealer within the meaning of the Securities Act or the Exchange
     Act (each such person including without limitation ATC being hereinafter
     sometimes referred to as an "indemnified person"), against any Claims,
     joint or several, to which such indemnified person may become subject,
     including without limitation under the Securities Act, the Exchange Act or
     any state securities or blue sky law, insofar as such Claims arise out of
     or are based upon any untrue statement or alleged untrue statement of a
     material fact contained or incorporated by reference in any Registration
     Statement or Prospectus or any amendment or supplement thereto or any
     document incorporated by reference therein, or arise out of or are based
     upon the omission or alleged omission to state therein a material fact
     required to be stated therein or necessary to make the statements therein,
     in light of the circumstances under which they were made, not misleading,
     provided that such untrue statement or alleged untrue statement or omission
     or alleged omission has been made or incorporated therein in reliance upon
     and in conformity with written information furnished to ATC by such
     Stockholder specifically stating that it is for use in preparation thereof,
     and will reimburse each such indemnified person for any legal or any other
     expenses reasonably incurred by ATC or such indemnified person in
     connection with investigating or defending, settling or satisfying any such
     Claim.  Such indemnity 

                                      -10-
<PAGE>
 
     shall remain in full force and effect regardless of any investigation made
     by or on behalf of such indemnified person and shall survive the transfer
     of such Registrable Securities by such Stockholder. In no event shall the
     liability of any such Stockholder hereunder be greater in amount than the
     dollar amount of the proceeds received by such Stockholder upon the sale of
     the Registrable Securities giving rise to such indemnification obligation.

          (c) Procedure.  Promptly after receipt by an indemnified party of
              ---------                                                    
     notice of the commencement of any action (including any governmental
     investigation or inquiry), such indemnified party will, if a claim in
     respect thereof is to be made against an indemnifying party, give written
     notice to such indemnifying party of the commencement thereof, but the
     omission so to notify the indemnifying party will not relieve it from any
     liability which it may have to any indemnified party otherwise than
     pursuant to the provisions of this Section and then only to the extent such
     indemnifying party has been prejudiced, or otherwise adversely affected
     thereby and in no event shall such failure relieve the indemnifying party
     from any other liability which it may have to the indemnified party.  In
     case any such action is brought against any indemnified party, and it
     notifies an indemnifying party of the commencement thereof, the
     indemnifying party will be entitled to participate in, and to the extent
     that it may wish, jointly with any other indemnifying party similarly
     notified, to assume the defense thereof, with counsel reasonably
     satisfactory to such indemnified party, and after notice from the
     indemnifying party to such indemnified party, the indemnifying party shall
     not, except as hereinafter provided, be responsible for any legal or other
     expenses subsequently incurred by such indemnified party in connection with
     the defense thereof, other than reasonable cost of investigation. No
     indemnifying party will consent to entry of any judgment or enter into any
     settlement which does not include as an unconditional term thereof the
     giving by the claimant or plaintiff to such indemnified party of a release
     from all liability in respect to such Claim.

          Such indemnified party shall have the right to employ separate counsel
     in any such action and to participate in the defense thereof, but the fees
     and expenses of such counsel shall be the expense of such indemnified
     party, unless (i) the indemnifying party has agreed to pay such fees and
     expenses, (ii) the indemnifying party shall have failed to assume the
     defense of such action or proceeding or has failed to employ counsel
     reasonably satisfactory to such indemnified party in any such action or
     proceeding, or (iii) the named parties to any such action or proceeding
     (including any impleaded parties) include both such indemnified party and
     the indemnifying party, and such indemnified party shall have been advised
     in writing by counsel that representation of both parties by the same
     counsel would be inappropriate due to actual or potential material
     differing interests between them (in which case, if such indemnified party
     notifies the indemnifying party in writing that it elects to employ
     separate counsel at the expense of the indemnifying party, the indemnifying
     party shall not have the right to assume the defense of such action or
     proceeding on behalf of such indemnified party, it being understood,
     however, that the indemnifying party shall not, in connection with any one
     such action or proceeding or separate but substantially similar or related
     actions or proceedings in the same jurisdiction arising out of the same
     general allegations or circumstances, be liable for the fees and expenses
     of more than one separate firm of attorneys at any time for such
     indemnified party and any other indemnified parties, which firm shall be
     designated in writing by such indemnified parties). The indemnifying party
     shall not be liable for any settlement of any such action or proceeding
     effected without its written consent, but if settled with its written
     consent, or if there be a final judgment for the plaintiff in any such
     action or proceeding, the indemnifying party agrees to indemnify and hold
     harmless such indemnified parties from and against any loss or liability by
     reason of such settlement or judgment.

          (d) Contribution.  If the indemnification provided for in this Section
              ------------                                                      
     or in Section 4 is unavailable, because prohibited or restricted by
     Applicable Law, to a party that would have been an 

                                      -11-
<PAGE>
 
     indemnified party under either such Section in respect of any Claims
     referred to therein, then each party that would have been an indemnifying
     party thereunder shall, in lieu of indemnifying such indemnified party,
     contribute to the amount paid or payable by such indemnified party as a
     result of such Claims in such proportion as is appropriate to reflect the
     relative fault of the indemnifying party on the one hand and such
     indemnified party on the other in connection with the statement or omission
     which resulted in such Claims, as well as any other relevant equitable
     considerations. The relative fault shall be determined by reference to,
     among other things, whether the untrue or alleged untrue statement of a
     material fact or the omission or alleged omission to state a material fact
     relates to information supplied by the indemnifying party or such
     indemnified party and the parties' relative intent, knowledge, access to
     information and opportunity to correct or prevent such statement or
     omission. Notwithstanding the provisions of this Section, a holder of
     Registrable Securities shall not, as an indemnified party, be required to
     contribute any amount in excess of the amount by which the total price at
     which the Registrable Securities sold by such indemnified party or its
     Affiliates and distributed to the public were offered to the public exceeds
     the amount of any damages which such indemnified party or its Affiliates
     have otherwise been required to pay by reason of such untrue or alleged
     untrue statement or omission or alleged omission. ATC and each holder of
     Registrable Securities agrees that it would not be just and equitable if
     contribution pursuant to this Section were determined by pro rata
     allocation or by any other method of allocation which does not take account
     of the equitable considerations referred to above in this Section. The
     amount paid or payable by an indemnified party as a result of the Claims
     referred to above in this Section or Section 4 shall include any legal or
     other expenses reasonably incurred by such indemnified party in connection
     with investigation or defending any such action or claim (which shall be
     limited as provided in Section 3(c) if the indemnifying party has assumed
     the defense of any such action in accordance with the provisions thereof).
     The obligations of each Stockholder under this Section 3(d) are several and
     not joint.

          No person guilty of fraudulent misrepresentation (within the meaning
     of Section 11(f) of the Securities Act) shall be entitled to contribution
     from any person who was not guilty of such fraudulent misrepresentation.

          Indemnification or, if appropriate, contribution, similar to that
     specified in the preceding provisions of this Section (with appropriate
     modifications) shall be given by ATC and each seller of Registrable
     Securities  with respect to any required registration or other
     qualification of Registrable Securities under any Applicable Law other than
     the Securities Act.

          In the event of any underwritten offering of Registrable Securities
     under the Securities Act pursuant to the provisions of Section 1, ATC and
     each Stockholder on whose behalf Registrable Securities shall have been
     registered agree to enter into an underwriting agreement, in standard form,
     with the underwriters, which underwriting agreement may contain additional
     provisions with respect to indemnification and contribution in lieu of the
     provisions of this Section.

          4.  Exchange Act Registration.
              ------------------------- 

          ATC covenants and agrees that, at its expense, until such time as the
     Stockholders no longer hold any Registrable Securities:

          (a) it will, if required by law, maintain a registration statement
     (containing such information and documents as the Commission shall specify)
     with respect to the ATC Common Stock under Section 12(b) or 12(g) of the
     Exchange Act effective and will file on time such 

                                      -12-
<PAGE>
 
     information, documents and reports as the Commission may require or
     prescribe for companies whose stock has been registered pursuant to said
     Section 12(b) or 12(g);

          (b) it will, if a registration statement with respect to the ATC
     Common Stock under Section 12(b) or Section 12(g) is effective, upon the
     request of any Stockholder, make whatever other filings with the Commission
     or otherwise make generally available to the public such financial and
     other information as any Stockholder may deem necessary or advisable in
     order to enable him to be permitted to sell shares of ATC Common Stock
     pursuant to the provisions of Rule 144 promulgated under the Securities Act
     (or any successor rule or regulation thereto or any statute hereafter
     adopted to replace or to establish the exemption that is now covered by
     said Rule 144);

          (c) it will, if not subject to Section 13 to 15(d) of the Exchange
     Act, upon the request of any Significant Stockholder made on or after
     December 31, 1998, make publicly available the information specified in
     subparagraph (c)(2) of said Rule 144, and will take such further action as
     any Stockholder may reasonably request, all to the extent required from
     time to time to enable such Stockholder to sell Registrable Securities
     without registration under the Securities Act within the limitation of the
     exemptions provided by said Rule 144 (or any successor rule or regulation
     to either thereof or any statute hereafter adopted to replace or to
     establish the exemption that is now covered by said Rule 144); and

          (d) it will, if not subject to Section 13 to 15(d) of the Exchange
     Act, upon the request of any Stockholder agree to furnish to a prospective
     purchaser (subject to the execution by it of a confidentiality agreement in
     form, scope and substance reasonably satisfactory to ATC) the information
     specified in subparagraph (d)(4) of Rule 144A promulgated under the
     Securities Act (or any successor rule or regulation thereto or any statute
     hereafter adopted to replace or to establish the exemption that is now
     covered by said Rule 144A), and will take such further action as any
     Stockholder may reasonably request, all to the extent required from time to
     time to enable such Stockholder to sell Registrable Securities without
     registration under the Securities Act within the limitation of the
     exemptions provided by said Rule 144A (or any successor rule or regulation
     thereto or any statute hereafter adopted to replace or to establish the
     exemption that is now covered by said Rule 144A); and

          (e) upon the request of any Stockholder, it will deliver to such
     Stockholder a written statement as to whether it has complied with the
     requirements of this Section.

     ATC represents and warrants that any such registration statement or any
information, documents or report filed with the Commission in connection
therewith or any information so made public shall not contain any untrue
statement of a material fact or omit to state a material fact required to be
stated therein or necessary in order to make the statements contained therein,
in light of the circumstances under which they were made, not misleading.  ATC
shall, to the extent permitted by Applicable Law, indemnify and hold harmless
(or to the extent the same is not enforceable, make contribution to) the
Stockholders, their partners, trustees, advisory committee members, officers,
directors, employees, representatives and agents, each broker, dealer or
underwriter (within the meaning of the Securities Act) acting for any
Stockholder in connection with any offering or sale by such Stockholder of
Registrable Securities or any person, firm or corporation controlling (within
the meaning of Section 15 of the Securities Act or Section 20 of the Exchange
Act) such Stockholder or any such broker, dealer or underwriter from and against
any and all Claims arising out of or resulting from any breach of the foregoing
representation or warranty, all on terms 

                                      -13-
<PAGE>
 
and conditions comparable to those set forth in Section 3; provided, however,
that ATC shall be given written notice and an opportunity to participate in,
and, to the extent that it may wish, to assume on terms and conditions
comparable to those set forth in Section 3, the defense thereof.

     5.   Termination of Registration Obligations.
          --------------------------------------- 

     The obligations of ATC to any Stockholder with respect to its rights of
registration provided for in Section 1:

          (a) shall continue until such time as Sullivan & Worcester LLP, or
     other counsel for ATC knowledgeable in securities law matters and
     reasonably acceptable to such Stockholder has delivered a written opinion
     to ATC and such Stockholder to the effect that either (i) such Stockholder
     has no further obligation to comply with the registration requirements of
     the Securities Act or to deliver a prospectus meeting the requirements of
     Section 10(a)(3) of the Securities Act in connection with further sales by
     such Stockholder of Registrable Securities or (ii) such Stockholder is able
     to sell all of the Registrable Securities owned by it pursuant to the
     provisions of Rule 144 under the Securities Act in a three-month period;
     and

          (b) shall not apply to any proposed sales or other dispositions or
     offers therefor of any Registrable Securities with respect to which
     Sullivan & Worcester LLP, or other counsel for ATC knowledgeable in
     securities law matters and reasonably acceptable to such Stockholder has
     delivered a written opinion to ATC and such Stockholder proposing to make
     such offer, sale or other disposition to the effect that such Stockholder
     has no obligation to comply with the registration requirements of the
     Securities Act or to deliver a prospectus meeting the requirements of
     Section 10(a)(3) of the Securities Act.

     Any such opinion (a copy of which shall be addressed to such Stockholder)
shall be reasonably satisfactory (in the case of such opinion as to form, scope
and substance) to such Stockholder.

     ATC shall, to the extent permitted by Applicable Law, indemnify and hold
harmless each Stockholder, its partners, trustees, advisory committee members,
officers, directors, employees, representatives and agents and each person, if
any, who controls such Stockholder within the meaning of either Section 15 of
the Securities Act or Section 20 of the Exchange Act, against any Claims to
which such Stockholder, or such partners, trustees, advisory committee members,
officers, directors, employees, representatives and agents or controlling
persons may become subject under the Securities Act, the Exchange Act or
otherwise, insofar as such Claims arise out of or are based upon the failure to
register the Registrable Securities because of the invocation by ATC of the
provisions of this Section under the Securities Act, all on terms and conditions
comparable to those set forth in Section 3; provided, however, that ATC shall be
given written notice and an opportunity to participate in, and to the extent
that it may wish, to assume, on terms and conditions comparable to those set
forth in Section 3, the defense thereof.

     The indemnification and contributions provisions of Sections 3 and 4 and
this Section, and the obligations of each Stockholder pursuant to the provisions
of Section 9, shall survive any termination of ATC's obligations pursuant to
this Section.

     6.   Registration Rights of Others.
          ------------------------------


                                      -14-
<PAGE>
 

     ATC represents and warrants that it has not previously entered into any
agreement with respect to its securities granting any registration rights to any
Person other than the 1998 Registration Rights Agreement.

     7.   Mergers, etc.
          ------------ 

     In addition to any other restrictions on mergers, consolidations and
reorganizations contained in the Restated Certificate of Incorporation, by-laws
or agreements of ATC, ATC covenants and agrees that it shall not, directly or
indirectly, enter into any merger, consolidation, sale of all or substantially
all of its assets or business, liquidation, dissolution or reorganization in
which ATC shall not be the surviving corporation unless the surviving
corporation shall, prior to such merger, consolidation or reorganization, agree
in a writing to assume all of the obligations of ATC under this Agreement, and
for that purpose references hereunder to "Registrable Securities" shall be
deemed to include the securities which such holders would be entitled to receive
in exchange for Registrable Securities pursuant to any such merger,
consolidation, sale of all or substantially all of its assets or business,
liquidation, dissolution or reorganization.

     8.   Annual and Quarterly Reports; Other Information.
          ----------------------------------------------- 

     ATC will deliver to each Stockholder so long as such Stockholder holds any
Registrable Securities:

          (a) as soon as practicable after the end of each fiscal year and each
     quarter, audited annual and unaudited consolidated quarterly financial
     statements of ATC, including a consolidated balance sheet, a consolidated
     statement of operations, and a consolidated statement of cash flow, for
     such year or quarter, all prepared in accordance with generally accepted
     accounting principles;

          (b) as soon as available, copies of all documents filed with the
     Commission; and

          (c) such other financial and other information as may, from time to
     time, be reasonably requested by any Significant Stockholder.

     9.   Withdrawals.
          ----------- 

     Any Stockholder may at any time withdraw any request made pursuant to
Section 1 for registration of its Registrable Securities.  Notwithstanding
anything in the foregoing provisions of this Section to the contrary, the
provisions of this Section shall not be applicable in the event that any such
withdrawal or withdrawals resulting in such termination is or are effected on
account of (a) ATC's failure to disclose any material fact required to be
disclosed in the registration statement or any prospectus relating to such
offering or (b) any material adverse change in ATC, its business, assets or
condition (financial or other).

     10.  Definitions.
          ----------- 

     As used herein, unless the context otherwise requires, the terms (or any
variant in the form thereof) set forth in this Agreement shall have the
respective meanings so set forth.  Terms defined in the singular shall have a
comparable meaning when used in the plural, and vice versa, and the reference to
                                                ---- -----                      
any gender shall be deemed to include all genders.  Unless otherwise defined or
the context otherwise clearly requires, terms for which meanings are provided in
this Agreement shall have such meanings when used in each 

                                      -15-
<PAGE>
 
agreement, notice, certificate, communication, opinion or other document
executed or required to be executed pursuant hereto or thereto or otherwise
delivered, from time to time, pursuant hereto or thereto.

     "Affiliate" of any Person shall mean any Person which, directly or
indirectly, owns or controls, is under common ownership or control with, or is
owned or controlled by, such Person.  A Person shall be deemed to be "controlled
by" any other Person if such other Person possesses, directly or indirectly,
power to direct or cause the direction of the management or policies of such
Person or the disposition of its assets or property, whether by stock, equity or
other ownership, contract, arrangement or understanding, or otherwise.

     "Agreement" is defined in the first paragraph.

     "Applicable Law" shall mean any Law of any Authority, whether domestic or
foreign, including without limitation all federal and state Laws, to which the
Person in question is subject or by which it or any of its business or
operations is subject or any of its property is bound.

     "ATC" is defined in the first paragraph.

     "Authority" shall mean any governmental or quasi-governmental authority,
whether executive, legislative, judicial, administrative or other, or any
combination thereof, including without limitation any federal, state,
territorial, county, municipal or other government or governmental or quasi-
governmental agency, arbitrator, board, body, branch, bureau or comparable
agency or Entity, commission, corporation, court, department, instrumentality,
mediator, panel, system or other political unit or subdivision or other Entity
of any of the foregoing, whether domestic or foreign.

     "Claims" shall mean, with respect to any Person, any and all debts,
liabilities, obligations, losses, damages, deficiencies,  assessments and
penalties of or against such Person, together with all Legal Actions, pending or
threatened, claims and judgments of whatever kind and nature relating thereto,
and all fees, costs, expenses and disbursements (including without limitation
reasonable attorneys' and other legal fees, costs and expenses) relating to any
of the foregoing.

     "Common Stock", "Class A Common", "Class B Common" or "Class C Common",
shall mean those respective securities described in the Restated Certificate of
Incorporation of ATC.

     "Commission" shall mean the Securities and Exchange Commission or any
successor Authority.

     "Excluded Offering" shall mean (a) an offering relating solely to dividend
reinvestment plans or stock option or other employee benefit plans, (b) any
merger, consolidation or acquisition, (c) any exchange or tender offer, whether
with existing security holders of ATC or any other Person, or (d) a firm
underwritten offering relating solely to convertible securities or units
consisting of securities senior to Common Stock and warrants, options and rights
to acquire Common Stock in which the managing underwriters shall have objected
to the inclusion of any Registrable Securities.

     "Entity" shall mean any corporation, firm, unincorporated organization,
association, partnership, a trust (inter vivos or testamentary), an estate of a
deceased, insane or incompetent individual, business trust, joint stock company,
joint venture or other organization, entity or business, whether acting in an
individual, fiduciary or other capacity, or any Authority.

                                      -16-
<PAGE>
 
     "Event" shall mean the existence or occurrence of any act, action,
activity, circumstances, condition, event, fact, failure to act, omission,
incident or practice, or any set or combination of any of the foregoing.

     "Exchange Act" shall mean the Securities Exchange Act of 1934, and the
rules and regulations of the Commission thereunder, all as from time to time in
effect, or any successor law, rules or regulations, and any reference to any
statutory or regulatory provision shall be deemed to be a reference to any
successor statutory or regulatory provision.

     "FCC" shall mean the Federal Communications Commission or any successor
Authority.

     "Law"  shall mean any (a) administrative, judicial, legislative or other
action, code, consent decree, constitution, decree, directive, enactment,
finding, law, injunction, interpretation, judgment, order, ordinance, policy
statement, proclamation, promulgation, regulation, requirement, rule, rule of
law, rule of public policy, settlement agreement, statute, or writ of any
Authority, domestic or foreign; (b) the common law, or other legal precedent; or
(c) arbitrator's, mediator's or referee's award, decision, finding or
recommendation.

     "Legal Action" shall mean, with respect to any Person, any and all
litigation or legal or other actions, arbitrations, counterclaims,
investigations, proceedings, requests for material information by or pursuant to
the order of any Authority or suits, at law or in arbitration, equity or
admiralty, whether or not purported to be brought on behalf of such Person,
affecting such Person or any of such Person's business, property or assets.

     "NASD" shall mean the National Association of Securities Dealers, Inc.

     "NASDAQ" shall mean the automatic quotation system of NASD.

     "Person" shall mean any natural individual or any Entity.

     "Prospectus" shall mean each prospectus included in any Registration
Statement, as amended or supplemented by any prospectus supplement with respect
to the terms of the offering of any portion of the Registrable Securities
covered by the Registration Statement and by all other amendments and
supplements to the prospectus, including each preliminary prospectus and post-
effective amendments and all material incorporated by reference in such
prospectus.

     "Registrable Securities" shall mean (a) all shares of Class A Common Stock
acquired by CSFB pursuant to the ATC Stock Purchase Agreement, and (b) all
shares of Common Stock of whatever series or class or other equity securities of
ATC derived from the Registrable Securities, whether as a result of merger,
consolidation, stock split, stock dividend, stock distribution, stock
combination, recapitalization or similar event.

     "Registration Expenses" shall mean all (or where appropriate any one or
more) of the following:

          (a)  all registration, filing and listing fees;

          (b)  fees and expenses of compliance with securities or blue sky laws
     (including without limitation reasonable fees and disbursements of counsel
     for the underwriters or selling holders in connection with blue sky and
     state securities qualifications of the Registrable Securities under the

                                      -17-
<PAGE>
 
     laws of such jurisdictions as the managing underwriters or the holders of
     not less than a majority in value (based on the proposed public offering
     price) of the Registrable Securities being sold may designate);

          (c)  printing (including without limitation expenses of printing or
     engraving certificates for the Registrable Securities in a form eligible
     for deposit with Depositary Trust Company and otherwise meeting the
     requirements of any securities exchange on which they are listed and of
     printing Prospectuses), word processing, messenger, telephone and delivery
     expenses;

          (d)  fees and disbursements of counsel for ATC, and reasonable fees
     and disbursements of counsel for the underwriters and for the selling
     holders of the Registrable Securities in accordance with the provisions of
     Section 1(c)(xiv) (subject to any provisions to the contrary in this
     Agreement);

          (e)  fees and disbursements of all independent public accountants of
     ATC (including without limitation the expenses of any annual or special
     audit and "cold comfort" letters required by the provisions of this
     Agreement);

          (f)  fees and disbursements of underwriters (excluding discounts,
     commissions or fees of underwriters), selling brokers, dealer managers or
     similar securities industry professionals relating to the distribution of
     the Registrable Securities or legal expenses of any Person other than ATC,
     the underwriters and the selling holders;

          (g)  securities act liability insurance if ATC so desires or if the
     underwriters or the holders of not less than a majority in value (based on
     the proposed public offering price) of the Registrable Securities being
     sold so require;

          (h)  fees and expenses of other Persons, including any experts,
     retained by ATC;

          (i)  fees and expenses incurred in connection with the listing of the
     Registrable Securities on each securities exchange on which securities of
     the same class are then listed;

          (j)  fees and expenses associated with any NASD filing required to be
     made in connection with any Registration Statement, including, if
     applicable, the fees and expenses of any "qualified independent
     underwriter" (and its counsel) that is required to be retained in
     accordance with the rules and regulations of the NASD;

          (k)  all other third party costs and expenses normally associated with
     the issuance and sale of newly issued public securities.

     "Registration Statement" shall mean any registration statement of ATC which
covers Registrable Securities pursuant to the provisions of this Agreement,
including the Prospectus, amendments, including post-effective amendments to
such registration statement, and supplements to such Prospectus and all exhibits
and all material incorporated by reference in such registration statement.

     "Securities Act" shall mean the Securities Act of 1933, and the rules and
regulations of the Commission thereunder, all as from time to time in effect, or
any successor law, rules or regulations, and 

                                      -18-
<PAGE>
 
any reference to any statutory or regulatory provision shall be deemed to be a
reference to any successor statutory or regulatory provision.

     "Significant Stockholder" shall mean CSFB (regardless of amount owned) or
any other Stockholder, or group of Stockholders acting together, which owns
shares of Common Stock with a market value of not less than $10,000,000;
provided, however, that notwithstanding the foregoing, in the event ATC is, at
the time of any request made pursuant to the provisions of Section 1(b),
eligible to file a Registration Statement on Form S-3 (or any successor form)
with respect to the proposed disposition of the Registrable Securities with
respect to which such request has been made, and such form is acceptable to the
holders making such request, the minimum market value of the Registrable
Securities shall be not less than $5,000,000.

     "Stockholders" shall mean CSFB and any persons who hereafter become
assignees pursuant to Section 11(a).

     "Subsidiary" shall mean, with respect to any Person, any Entity a majority
of the capital stock ordinarily entitled to vote for the election of directors,
or if no such voting stock is outstanding a majority of the equity interests, of
which is owned directly or indirectly by such Person or any Subsidiary of such
Person.

     11.  Miscellaneous.
          ------------- 

     (a) Assignment; Successors and Assigns.  In the event that ATC shall be
         ----------------------------------                                 
merged with, or consolidated into, any other Entity or in the event that it
shall sell and transfer substantially all of its assets to another Entity, the
terms of this Agreement shall inure to the benefit of, and be assumed by, the
Entity resulting from such merger or consolidation, or to which ATC's assets
shall be sold and transferred.  Anything in this Agreement to the contrary
notwithstanding, the term "Stockholders" as used in this Agreement shall be
deemed to include the holders from time to time of any of the Registrable
Securities, whether or not they become parties to this Agreement, except for
holders who have acquired Registrable Securities in connection with an offering
registered under the Securities Act or pursuant to sales made in accordance with
Rule 144 (or any successor rule or regulation or statute in substitution
therefor). The rights to cause ATC to register Registrable Securities pursuant
to Section 1 may be assigned in connection with any transfer or assignment by a
holder of Registrable Securities; provided, however, that (i) such transfer may
otherwise be effected in accordance with applicable securities laws and (ii)
such transfer is effected in compliance with the restrictions on transfer
contained in any agreement between ATC and such holder. ATC's obligations under
this Agreement shall not be assigned, and its duties under this Agreement shall
not be delegated, except as provided in the first sentence of this Section.
Nothing in this Agreement expressed or implied is intended to and shall not be
construed to confer upon or create in any Person (other than the parties hereto
and their permitted successors and assigns) any rights or remedies under or by
reason of this Agreement, including without limitation any rights to enforce
this Agreement.

     (b) Specific Performance; Other Rights and Remedies.  Each party recognizes
         -----------------------------------------------                        
and agrees that the other parties' remedies at law for any breach of the
provisions of this Agreement would be inadequate and agrees that for breach of
such provisions, each such party shall, in addition to such other remedies as
may be available to it at law or in equity or as provided in this Agreement, be
entitled to injunctive relief and to enforce its rights by an action for
specific performance to the extent permitted by Law.  Each party hereby waives
any requirement for security or the posting of any bond or other surety in
connection with any 

                                      -19-
<PAGE>
 
temporary or permanent award of injunctive, mandatory or other equitable relief.
Nothing herein contained shall be construed as prohibiting any party from
pursuing any other remedies available to it for such breach or threatened
breach, including without limitation the recovery of damages.

     (c) Expenses.  CSFB shall pay the expenses incident to the negotiation,
         --------                                                           
preparation, performance and enforcement of this Agreement (including all fees
and expenses of its and ATC's counsel, accountants and other consultants,
advisors and representatives for all activities of such persons undertaken
pursuant to this Agreement), except to the extent otherwise specifically set
forth in this Agreement.

     (d) Entire Agreement.  This Agreement constitutes the entire agreement
         ----------------                                                  
among the parties with respect to the subject matter hereof and supersedes all
prior agreements, arrangements, covenants, promises, conditions, understandings,
inducements, representations and negotiations, expressed or implied, oral or
written, among them as to such subject matter.

     (e) Waivers; Amendments.  Notwithstanding anything in this Agreement to the
         -------------------                                                    
contrary, amend ments to and modifications  of this Agreement may be made,
required consents and approvals may be granted, compliance with any term,
covenant, agreement, condition or other provision set forth herein may be
omitted or waived, either generally or in a particular instance and either
retroactively or prospectively with, but only with, the written consent of ATC
(to the extent it is entitled to the benefit thereof) and (i) with respect to
the rights of the Stockholders set forth in Section 1(b), including without
limitation the definition of Significant Stockholder, two-thirds (2/3) in
interest of the Stockholders, and (ii) with respect to all other rights and
obligations of the Stockholders, a majority in interest of the Stockholders (to
the extent they are entitled to the benefit thereof or obligated thereby);
provided, however, that in the event any such amendment, modification, consent,
approval or waiver shall be for the benefit of or materially adverse to less
than all of the Stockholders, such amendment, modification, consent, approval or
waiver shall require a majority in interest of those Stockholders who are not so
benefitted or who are so materially adversely affected.

     (f) Notices.  All notices and other communications which by any provision
         -------                                                              
of this Agreement are required or permitted to be given shall be given in
writing and shall be (a) mailed by first-class or express mail, postage prepaid,
(b) sent by telex, telegram, telecopy or other form of rapid transmission,
confirmed by mailing (by first class or express mail, postage prepaid) written
confirmation at substantially the same time as such rapid transmission, or (c)
personally delivered to the receiving party (which if other than an individual
shall be an officer or other responsible party of the receiving party).  All
such notices and communications shall be mailed, sent or delivered as follows:

     If to American Tower Corporation, at

               116 Huntington Avenue
               Boston, MA 02116
               Attention: Steven B. Dodge, Chairman of the Board and Chief
                          Executive Officer
               Facsimile: (617) 375-7575

          with a copy to:

               Sullivan & Worcester LLP
               One Post Office Square
               Boston, MA  02109
               Attention:  Norman A. Bikales, Esq.
               Facsimile:  (617) 338-2880

                                      -20-
<PAGE>
 
     If to CSFB:

               11 Madison Avenue
               New York, New York  10010
               Attention:  Kristin M. Allen, Managing Director
               Facsimile:  (212) 325-8021

          with a copy to:

               Sullivan &Cromwell
               125 Broad Street
               New York, NY  10004
               Attention:  John T. Bostelman
               Facsimile:  (212) 558-3588

     (g) Severability.  If any provision of this Agreement shall be held or
         ------------                                                      
deemed to be, or shall in fact be, invalid, inoperative, illegal or
unenforceable as applied to any particular case in any jurisdiction or
jurisdictions, or in all jurisdictions or in all cases, because of the
conflicting of any provision with any constitution or statute or rule of public
policy or for any other reason, such circumstance shall not have the effect of
rendering the provision or provisions in question invalid, inoperative, illegal
or unenforceable in any other jurisdiction or in any other case or circumstance
or of rendering any other provision or provisions herein contained invalid,
inoperative, illegal or unenforceable to the extent that such other provisions
are not themselves actually in conflict with such constitution, statute or rule
of public policy, but this Agreement shall be reformed and construed in any such
jurisdiction or case as if such invalid, inoperative, illegal or unenforceable
provision had never been contained herein and such provision reformed so that it
would be valid, operative and enforceable to the maximum extent permitted in
such jurisdiction or in such case, except when such reformation and construction
could operate as an undue hardship on either party, or constitute a substantial
deviation from the general intent and purpose of such party as reflected in this
Agreement.  The parties shall endeavor in good faith negotiations to replace the
invalid, inoperative, illegal or unenforceable provisions with valid, operative,
legal and enforceable provisions the economic effect of which comes as close as
possible to that of the invalid, inoperative, illegal or unenforceable
provisions.

     (h) Counterparts.  This Agreement may be executed in several counterparts,
         ------------                                                          
each of which shall be deemed an original, but all of which together shall
constitute one and the same instrument, binding upon all the parties hereto.  In
pleading or proving any provision of this Agreement, it shall not be necessary
to produce more than one of such counterparts.

     (i) Section Headings.  The headings contained in this Agreement are for
         ----------------                                                   
reference purposes only and shall not in any way affect the meaning or
interpretation of this Agreement.

     (j) Governing Law.  The validity, interpretation, construction and
         -------------                                                 
performance of this Agreement shall be governed by the applicable laws of the
United States of America and the domestic 

                                      -21-
<PAGE>
 
substantive laws of the State of New York without giving effect to any choice or
conflict of laws provision or rule that would cause the application of domestic
substantive laws of any other jurisdiction.

     (k) Further Acts.  Each party agrees that at any time, and from time to
         ------------                                                       
time, before and after the consummation of the transactions contemplated by this
Agreement, it will do all such things and execute and deliver all such
agreements, assignments, instruments, other documents and assurances, as any
other party or its counsel reasonably deems necessary or desirable in order to
carry out the terms and conditions of this Agreement and the transactions
contemplated hereby or to facilitate the enjoyment of any of the rights created
hereby or to be created hereunder.

                                      -22-
<PAGE>
 
     IN WITNESS WHEREOF, the parties have executed or caused to be executed
this Agreement as of the date set forth in the first paragraph hereof.

                      American Tower Corporation


                      By: 
                          -------------------------------------
                            Name:  Steven B. Dodge
                            Title: Chairman of the Board and 
                                   Chief Executive Officer
 

                      Credit Suisse First Boston Corporation


                      By: 
                          -------------------------------------
                            Name:
                            Title:

                                      -23-

<PAGE>
 
                                                                      EXHIBIT 21
                                                                      ----------

                  SUBSIDIARIES OF AMERICAN TOWER CORPORATION
                  ------------------------------------------
 
Information is as of December 31,1998 except when noted.

- --------------------------------------------------------------------------------

                                                 Jurisdiction of Incorporation
                    Subsidiary                          or Organization
                    ----------                          ---------------
- --------------------------------------------------------------------------------
   American Towers, Inc.                                    Delaware
- --------------------------------------------------------------------------------
   ATC Operating Inc.                                       Delaware
- --------------------------------------------------------------------------------
   ATC LP Inc.                                              Delaware
- --------------------------------------------------------------------------------
   ATC GP Inc.                                              Delaware
- --------------------------------------------------------------------------------
   ATC Holding, Inc.                                        Delaware
- --------------------------------------------------------------------------------
   American Tower Rental Holding Corporation                Delaware
- --------------------------------------------------------------------------------
   American Tower Rental, Inc.                              Delaware
- --------------------------------------------------------------------------------
   National Telecommunication Advisors, LLC (1)          Massachusetts
- --------------------------------------------------------------------------------
   ATC Tower Corp.                                          Delaware
- --------------------------------------------------------------------------------
   US Sitelease, Inc.                                        Kansas
- --------------------------------------------------------------------------------
   HHR, Inc.                                                 Kansas
- --------------------------------------------------------------------------------
   Westark Towers, Incorporated                             Arkansas
- --------------------------------------------------------------------------------
   Gritz Tower Maintenance Company                           Texas
- --------------------------------------------------------------------------------
   ATC-Prime I, LLC                                         Delaware
- --------------------------------------------------------------------------------
   ATC-Prime II, LLC                                        Delaware
- --------------------------------------------------------------------------------
   Grid Towers, LLC                                         Georgia
- --------------------------------------------------------------------------------
   American Tower, L.P. (2)                                 Delaware
- --------------------------------------------------------------------------------
   ATS Needham, LLC (3)                                     Delaware
- --------------------------------------------------------------------------------
   ATS/PCS, LLC (4)                                         Delaware
- --------------------------------------------------------------------------------
   Towersites Monitoring, Inc. (5)                          Delaware
- --------------------------------------------------------------------------------
   American Teleports Corporation (6) (14)                  Delaware
- --------------------------------------------------------------------------------
   OmniAmerica Holdings Corporation (7)                     Delaware
- --------------------------------------------------------------------------------
   South Atlantic Tower Corp. (7)                           Delaware
- --------------------------------------------------------------------------------
   OmniTower, Ltd. (7) (8)                                  Florida
- --------------------------------------------------------------------------------
   Novak & Lackey Construction Co., Inc. (7)                Oklahoma
- --------------------------------------------------------------------------------
   Microwave Tower Service, Inc. (7)                         Oregon
- --------------------------------------------------------------------------------
   Specialty Management, Inc. (7)                            Nevada
- --------------------------------------------------------------------------------
<PAGE>
 
- --------------------------------------------------------------------------------
   Specialty Constructors, Inc. (7)                        New Mexico
- --------------------------------------------------------------------------------
   Specialty Fortress, Inc. (7)                              Nevada
- --------------------------------------------------------------------------------
   OmniAmerica Development Corp. (7)                         Nevada
- --------------------------------------------------------------------------------
   Specialty Constructors Coatings, Inc. (7)                 Nevada
- --------------------------------------------------------------------------------
   Specialty Combined Resources, Inc. (7)                    Texas
- --------------------------------------------------------------------------------
   Specialty Training Centers, Inc. (7)                      Nevada
- --------------------------------------------------------------------------------
   OmniAmerica Towers, Inc. (7)                             Delaware
- --------------------------------------------------------------------------------
   American Tower Merger Corporation (9)                    Delaware
- --------------------------------------------------------------------------------
   TeleCom Towers, L.L.C. (10)                              Delaware
- --------------------------------------------------------------------------------
   Mid-Pacific Telecom Communications Co. (10)               Nevada
- --------------------------------------------------------------------------------
   Signal Tower Company, Inc. (10)                          New York
- --------------------------------------------------------------------------------
   Mountain Top Management, Inc. (10)                       Colorado
- --------------------------------------------------------------------------------
   Western Site Management, LLP (10) (11)                   Colorado
- --------------------------------------------------------------------------------
   Mountain Top-Telecom, L.L.C. (10) (12)                   Colorado
- --------------------------------------------------------------------------------
   Haysville Towers, L.L.C. (10) (13)                        Kansas
- --------------------------------------------------------------------------------

- --------------------

(1)  99.9% owned by ATC Tower Corp. and 0.1% owned by American Towers, Inc.
(2)  99% owned by ATC LP, Inc. and 1% owned by ATC GP, Inc.
(3)  45.23% owned by American Tower, L.P. and 34.77% owned by American Towers,
     Inc.
(4)  70% owned by American Tower, L.P.
(5)  Incorporated as of January 26, 1999.
(6)  Incorporated as of February 17, 1999.
(7)  Entity was acquired on February 25, 1999 pursuant to the consummation of
     the merger by and among American Tower Corporation, American Towers, Inc.
     and OmniAmerica, Inc., pursuant to which OmniAmerica, Inc. merged with and
     into American Towers, Inc., with American Towers, Inc. as the surviving
     corporation.
(8)  99% owned by OmniAmerica Towers, Inc. and 1% owned by South Atlantic Tower
     Corp.
(9)  Incorporated as of February 25, 1999.
(10) Entity was acquired on February 26, 1999 pursuant to the consummation of
     the merger by and among American Tower Corporation, American Towers, Inc.,
     ATC Merger Corporation and TeleCom Towers, L.L.C. , pursuant to which ATC
     Merger Corporation merged with and into TeleCom Towers, L.L.C., with
     TeleCom Towers, L.L.C. as the surviving entity.
(11) 67% owned by Mountain Top Management, Inc. and 33% owned by TeleCom Towers,
     L.L.C.
(12) 90% owned by TeleCom Towers, L.L.C. and 10% owned by Mountain Top
     Management, Inc.
(13) 67% owned by TeleCom Towers, L.L.C.
(14) 100% owned by American Tower, L.P.








<PAGE>
 
                                                                     Exhibit 23
 
                         INDEPENDENT AUDITORS' CONSENT
 
  We consent to the incorporation by reference in Registration Statement Nos.
333-72927, 333-56331 and 333-51959 of American Tower Corporation and
subsidiaries on Form S-8 of our report dated March 4, 1999, appearing in the
Annual Report on Form 10-K of American Tower Corporation for the year ended
December 31, 1998.
 
DELOITTE & TOUCHE LLP
 
Boston, Massachusetts
March 19, 1999

<TABLE> <S> <C>

<PAGE>
 
<ARTICLE> 5
<MULTIPLIER> 1,000
       
<S>                             <C>
<PERIOD-TYPE>                   12-MOS
<FISCAL-YEAR-END>                          DEC-31-1998
<PERIOD-END>                               DEC-31-1998
<CASH>                                         186,175
<SECURITIES>                                         0
<RECEIVABLES>                                   16,736
<ALLOWANCES>                                     1,230
<INVENTORY>                                          0
<CURRENT-ASSETS>                               207,585
<PP&E>                                         472,483
<DEPRECIATION>                                  23,007
<TOTAL-ASSETS>                               1,502,343
<CURRENT-LIABILITIES>                          115,635
<BONDS>                                        281,129
                                0
                                          0
<COMMON>                                         1,083
<OTHER-SE>                                   1,090,663
<TOTAL-LIABILITY-AND-EQUITY>                 1,502,343
<SALES>                                              0
<TOTAL-REVENUES>                               103,544
<CGS>                                                0
<TOTAL-COSTS>                                  113,815
<OTHER-EXPENSES>                                17,871
<LOSS-PROVISION>                                 1,139
<INTEREST-EXPENSE>                              23,229
<INCOME-PRETAX>                                (42,441)
<INCOME-TAX>                                     4,491
<INCOME-CONTINUING>                            (37,950) 
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                  8,892
<CHANGES>                                            0
<NET-INCOME>                                   (46,842)
<EPS-PRIMARY>                                   (0.59)
<EPS-DILUTED>                                   (0.59)
        

</TABLE>


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