Document:

<PAGE>

                                                                   EXHIBIT 10.37

[iAsiaWorks, Inc. Logo]                              AsiaWorks, Inc.
                                                      U.S. HEADQUARTERS
                                                      2000 Alameda de las Pulgas
                                                      Suite 126
                                                      San Mateo, CA 94403
                                                      United States of America
                                                      Tel: 650.524.1790
                                                      Fax: 650.570.6405
                                                      www.iasiaworks.com

       iAsiaWorks
       Global Technology. Asian Focus.

Private & Confidential/Addressee Only

October 12, 2001

Dennis Muse
[ADDRESS INTENTIONALLY OMITTED]

Dear Dennis,

This letter sets forth the separation and severance agreement (the "Agreement")
which iAsiaWorks, Inc. (the "Company") is offering to you to aid in your
employment transition.

1.   Separation: Your last day of employment with the Company will be October
     ----------
     12, 2001, (the "Separation Date"). However, for purposes of this Agreement,
     and with respect to your Original Agreement (as defined herein), it is
     agreed that you have been terminated Without Cause and, other than as set
     forth in this Agreement, and would be entitled to all rights and privileges
     which that entails under the Original Agreement. Although you will no
     longer be an employee of the Company, following the Separation Date, the
     Board of Directors of the Company has requested and you have agreed, to
     remain as a member of the Company's Board of Directors.

2.   Accrued Salary and Vacation: On or before the Separation Date, the Company
     ---------------------------
     will pay you all accrued salary, and all accrued and unused vacation earned
     through the Separation Date, subject to standard payroll deductions and
     withholdings. You are entitled to these payments regardless of whether or
     not you sign this Agreement.

3.   Return of Company Property: Unless otherwise agreed, you must have returned
     --------------------------
     all Company Documents and Materials as provided in the Proprietary
     Information and Inventions Agreement which you have signed, including
     without limitation laptop computers, cell phones, calling cards, printers,
     fax machines, LCD projectors, security badges, office keys, and the like,
     and all Company documents (and copies of documents), including, but not
     limited to, Company files, notes, drawings, records, business plans and
     forecasts, financial information, specifications, computer-recorded
     information, and any materials of any kind which contain or embody any
     proprietary or confidential information of the Company (and all
     reproductions thereof). For the avoidance of doubt, the severance
     settlement, as below, being offered to you under the terms of this
     Agreement, is fully contingent upon your full compliance with the terms
     regarding Return of Company Property, as identified in this clause of this
     Agreement.

<PAGE>

4.   Settlement:
     -----------

     (a)  Severance. Your original employment agreement with the Company, dated
          ---------
          April 20, 2001, as amended (the "Original Agreement"), provided for no
          severance upon termination of employment with the Company outside of a
          Change of Control (as defined therein). You and the Company have each
          agreed, that because of the company's difficult financial condition,
          and in light of your recent contributions to the Company, the Company
          will pay you, as severance, the sum of money which is equivalent to
          two (2) months of your base wage in effect as of the "Effective Date",
          as defined in paragraph 16 below subject to standard payroll
          deductions and withholdings (the "Settlement Payment"). This amount
          will be paid in one (1) lump sum within two (2) calendar days of the
          "Effective Date" as defined in paragraph 16 below.

     (b)  Benefits. The Company agrees that it will pay all required premiums to
          --------
          ensure continued health and dental benefits for you and your family
          from the Separation Date until, and including, December 31, 2001.

     (c)  Stock Grant. As has been approved by the Board of Directors of the
          -----------
          Company, you will be granted an option to purchase 200,000 shares of
          iAsiaWorks' common stock at the price in effect of time of approval
          (the "Option"). All shares of common stock covered by the Option shall
          be fully vested upon grant and shall be subject to and adjusted
          accordingly for stock splits and reverse splits.

5.   Stock Options; Stock Purchase: Your rights, if any, to purchase shares of
     -----------------------------
     the Common Stock of the Company remain governed by and subject to the
     iAsiaWorks, Inc. 2000 Stock Incentive Plan Stock Option Agreement between
     you and the Company (the "Stock Option Agreement"). You must exercise any
     vested shares within one (1) calendar year of the Separation Date. Except
     as described herein, your right, if any, to exercise those shares which
     have vested as of the Separation Date shall be subject to and in accordance
     with the terms of the Stock Option Agreement(s). All terms of the Stock
     Option Agreement(s) remain in full force and effect. Similarly, your
     rights, if any under the iAsiaWorks, Inc., Employee Stock Purchase Plan
     continue to be governed by the documents governing said iAsiaWorks, Inc.,
     Employee Stock Purchase Plan. .

6.   No Further Compensation: You acknowledge that, except as expressly provided
     -----------------------
     in this Agreement, you will not receive any additional salary, bonuses,
     vesting of stock options, stock,

<PAGE>

     commissions, other compensation, severance or benefits from the Company
     after the Separation Date; provided, however, that you may be eligible to
     receive additional compensation, in the form of cash or stock, for your
     continued service with the Company as a member of the Company's Board of
     Directors.

7.   Nondisparagement: You agree not to criticize, denigrate, or disparage the
     ----------------
     Company, any of its employees, representatives, agents, officers,
     directors, subsidiaries, affiliated entities, business interests, pursuits,
     and products or services.

8.   Release of Claims: On behalf of yourself and your heirs and assigns, you
     -----------------
     hereby forever release the Company and its owners, stockholders, parent
     corporation[s], affiliates, divisions, subsidiaries, assigns and
     affiliates, predecessors, successors, officers, managers, employees,
     insurers, representatives and agents from all claims, liabilities, demands,
     causes of action, costs, expenses, attorneys fees, damages, indemnity and
     obligation of every kind and nature, or otherwise, known and unknown,
     suspected and unsuspected, disclosed and undisclosed, arising out of or in
     any way related to agreements, events, acts or conduct at any time prior to
     and including the date you sign this Agreement, including but not limited
     to all claims based upon contract, tort or statute arising out of, based
     upon, or relating to your hire, offer letter, employment, remuneration or
     termination from employment with the Company, including any claims arising
     under Title VII of the Civil rights Act of 1964, as amended; the Equal Pay
     Act, as amended; the Age Discrimination in Employment Act ("ADEA"), as
     amended; the Employee Retirement Income Security Act, as amended; the Older
     Workers Benefit Protection Act; as amended; the California Fair Employment
     and Housing Act, as amended; the California Labor Code, as amended; and/or
     any other local, state or federal laws and regulations governing
     discrimination in employment, the payment of wages and benefits, and all
     other laws and regulations relating to employment. You acknowledge that
     your decision to sign this Agreement is knowing and voluntary. This
     Agreement does not apply to any claims of age discrimination under ADEA
     arising after the date you sign this Agreement, and does not apply to
     claims for unemployment insurance or workers' compensation benefits. This
     Agreement does not affect your rights, if any, under the Company's 401(k)
     plan; nor does is it affect your rights, or those of your eligible
     dependents, if any, to health care continuation benefits pursuant to the
     Consolidated Omnibus Budget Reconciliation Act (COBRA). The Company,
     however, acknowledges and agrees that this release does not apply to,
     release, or in any way limit the Company's (including, but not limited to,
     its affiliates, subsidiaries, divisions, assigns, and insurers) obligation
     to indemnify you for any losses, judgments, settlement payments, attorneys'
     fees, court costs, or litigation expenses incurred or sustained by you as a
     direct or indirect result of, or arising out of, your employment with the
     Company or your service as a member of the Company's Board of Directors:
     (a) to the extent such indemnity is available under the Company's
     director's and officer's liability insurance policy (the Company
     acknowledges the

<PAGE>

     existence of policy # 473-14-94 entered into with National Union Fire
     Insurance Company of Pittsburgh, PA (an AIG company) and policy # ELU
     81898-00 entered into with XL USA (Greenwich Insurance Company)), (b) to
     the extent such indemnity is authorized by the Company's articles or
     by-laws, and (c) to the extent permitted by law. The Company acknowledges
     and agrees that its obligation to indemnify you includes the obligation to
     advance to you reasonable attorneys' fees, court costs, and litigation
     expenses when and as such attorneys' fees and expenses are incurred by you
     in the defense of any claim, subpoena, investigation or civil or criminal
     action. Furthermore, notwithstanding anything to the contrary contained in
     this Agreement, the obligation to indemnify you and the terms of your
     Indemnification Agreement with the Company, dated April 23, 2001 (the
     "Indemnification Agreement"), shall remain in full effect so long as you
     continue to serve as a member of the Company's Board of Directors and/or
     you may be subject to litigation or a claim resulting from your service as
     an employee or member of the Company's Board of Directors.

9.   General Release. You expressly waive and release any and all rights and
     ---------------
     benefits under Section 1542 of the Civil Code of the State of California
     (or any analogous law of any other state), which reads as follows:

               A general release does not extend to claims which the
               creditor does not know or suspect to exist in his favor
               at the time of executing the release, which, if known
               by him, must have materially affected his settlement
               with the debtor.

     Furthermore, you and the Company agree and understand that if, hereafter,
     they discover facts different from or in addition to those which they now
     know or believe to be true, the waivers contained within this Agreement
     shall be and remain effective in all respects.

10.  Right to Advice of Counsel: You have the right to consult with a lawyer so
     --------------------------
     that you are fully aware of your rights and obligations under this
     Agreement.

11.  Non-Admission. Nothing contained in this letter shall constitute or be
     -------------
     treated as an admission by you or the Company of liability, of any
     wrongdoing, or of any violation of law.

12.  Confidential Information and Invention Assignment Agreement;
     ------------------------------------------------------------
     Non-Solicitation of Company Employees. At all times in the future, you will
     -------------------------------------
     remain bound by the Company's Proprietary Information and Inventions
     Agreement. It is a condition of your eligibility for benefits under this
     Agreement that you have signed and delivered to the Company the Proprietary
     Information and Inventions Assignment Agreement. You understand and agree,
     pursuant to Section F of the

<PAGE>

     Proprietary Information and Inventions Agreement, that during the term of
     your employment and for one (1) year thereafter, you will not encourage or
     solicit any employee of the Company to leave the Company for any reason or
     to accept employment with any other company, and that as part of this
     restriction, you agree not to interview or provide any input to any third
     party regarding any such person during the period in question.

13.  Sole Agreement. You agree that this Agreement, in addition to the
     --------------
     Proprietary Information and Inventions Assignment Agreement, the
     Indemnification Agreement and the Stock Option Agreement, constitutes an
     integration of the entire understanding and agreement between you and the
     Company with respect to the matters referred to in this Agreement, the
     Proprietary Information and Inventions Assignment Agreement, the
     Indemnification Agreement and the Stock Option Agreement. Any
     representation, promise or condition, whether written or oral, between you
     and the Company with respect to the matters referred to in this Agreement,
     which is not specifically incorporated in this Agreement shall not be
     binding upon either you or the Company and both you and the Company
     acknowledge that neither you nor the Company have relied, in entering into
     this Agreement, upon any representations, promises or conditions not
     specifically set forth in this Agreement, the Proprietary Information and
     Inventions Assignment Agreement and the Stock Option Agreement. No prior
     oral or written understanding, covenant or Agreement between you and the
     Company, including the Original Agreement, with respect to matters referred
     to in this Agreement, shall survive the execution of this Agreement;
     provided, however, that Original Agreement may be revived under limited
     circumstances pursuant to Paragraph 14 herein. Both you and the Company
     assume the risk of any misrepresentation, concealment or mistake, and if
     either you or the Company should subsequently discover that any fact relied
     upon in entering into this Agreement was untrue, or that any fact was
     concealed, or that the understanding of the facts was incorrect, neither
     you nor the Company will be entitled to set aside this Agreement by reason
     thereof.

14.  Condition to Mutual Release of Claims. You and the Company agree that the
     -------------------------------------
     mutual release of claims in Paragraph 8 is conditioned upon your receipt
     and retention of the Settlement Payment and other consideration as
     contemplated by this Agreement. Specifically, if, and only if, you are
     compelled by a judgment or order of a court of competent jurisdiction or in
     good faith settlement demand to disgorge, return, or pay over to the
     Company or any third-party (if such payment is directly related to the
     Settlement Payment) any portion of the Settlement Payment, including but
     not limited to any right of repayment arising by operation of any law
     relating to avoidable transfers made by those who are the object of any
     bankruptcy, receivership, or insolvency proceeding, including any
     assignment for the benefit of creditors, any reorganization case under the
     bankruptcy laws or any successor thereto ("Bankruptcy"). The parties agree
     that if the releases herein become ineffective, the Company shall once
     again recognize the Original Agreement and it shall once again take
     precedence over this Agreement, which shall be deemed

<PAGE>

     null and void. Additionally, you shall be free to pursue any and all claims
     against the Company in either litigation or by way of arbitration (unless
     those claims are required to be brought in bankruptcy court) and shall be
     entitled to claim any amounts due under the Original Agreement.

15.  Time to Consider Agreement. You have up to twenty-one (21) calendar days
     --------------------------
     after receipt of this letter within which to review it, and to discuss it
     with an attorney of your own choosing regarding whether or not you wish to
     execute it.

16.  Revocation Period. You have seven (7) calendar days after you have signed
     -----------------
     this Agreement during which time you may revoke this Agreement. If you wish
     to revoke this Agreement, you may do so by delivering a letter of
     revocation to Derrick Hansen at c/o iAsiaWorks, 2000 Alameda de las Pulgas,
     Suite 126, San Mateo, CA 94403, during the seven (7) calendar day
     revocation period. Because of this revocation period, you understand that
     the terms and conditions set forth in this letter shall not become
     effective or enforceable until the eighth (8th) calendar day after the date
     you sign this letter (the "Effective Date").

17.  Severability, Governing Law. If any provision of this Agreement is
     ---------------------------
     determined to be invalid or unenforceable, in whole or in part, this
     determination will not affect any other provision of this Agreement and the
     provision in question shall be modified by the court so as to be rendered
     enforceable. This Agreement shall be deemed to have been entered into and
     shall be construed and enforced in accordance with the laws of the State of
     California as applied to contracts made and to be performed entirely within
     California.

<PAGE>

If this Agreement is acceptable to you, please sign below and return the
original to me. You may keep the enclosed copy.

I thank you for your efforts on behalf of iAsiaWorks, Inc. and wish you luck in
your future endeavors.

Sincerely,

IASIAWORKS,INC.

By: /s/ Nicholas K. Pianim
    ----------------------------
Name: Nicholas K. Pianim
      --------------------------
Title: CEO
       -------------------------

My agreement with the above terms is signified by my signature below.
Furthermore, I acknowledge that I have read and understand this letter, have
been advised to discuss it with an attorney of my own choosing, and that I sign
this release of all claims voluntarily, with and full appreciation.

Dated: 10/14/2001                        /s/ Dennis Muse
       ------------------------          --------------------------------
                                                  Employee Name<PAGE>

                                                                   Exhibit 10.01

                                  DEED OF LEASE

                                     between

                            TST WATERVIEW I, L.L.C.,
                      a Delaware limited liability company

                                    Landlord

                                       and

                                 VERISIGN, INC.,
                             a Delaware corporation

                                     Tenant

                          Waterview I at Woodland Park
                      Dulles Toll Road at Centreville Road
                             Herndon, Virginia 20171

                            Dated as of July 19, 2001

<PAGE>

                                TABLE OF CONTENTS
                                -----------------

<TABLE>
<CAPTION>
                                                                                            Page
<S>                                                                                         <C>
ARTICLE 1 BASIC LEASE PROVISIONS...........................................................   1
          ----------------------
ARTICLE 2 PREMISES, TERM, RENT.............................................................   4
          --------------------
ARTICLE 3 USE AND OCCUPANCY................................................................   7
          -----------------
ARTICLE 4 CONDITION OF THE PREMISES........................................................   10
          -------------------------
ARTICLE 5 ALTERATIONS......................................................................   13
          -----------
ARTICLE 6 FLOOR LOAD.......................................................................   15
          ----------
ARTICLE 7 REPAIRS..........................................................................   16
          -------
ARTICLE 8 OPERATING EXPENSES AND TAXES.....................................................   18
          ----------------------------
ARTICLE 9 REQUIREMENTS OF LAW..............................................................   28
          -------------------
ARTICLE 10 SUBORDINATION...................................................................   30
           -------------
ARTICLE 11 SERVICES AND UTILITIES..........................................................   34
           ----------------------
ARTICLE 12 INSURANCE.......................................................................   39
           ---------
ARTICLE 13 DESTRUCTION - FIRE OR OTHER CAUSE...............................................   43
           ---------------------------------
ARTICLE 14 EMINENT DOMAIN..................................................................   43
           --------------
ARTICLE 15 ASSIGNMENT AND SUBLETTING.......................................................   47
           -------------------------
ARTICLE 16 ACCESS..........................................................................   55
           ------
ARTICLE 17 DEFAULT.........................................................................   55
           -------
ARTICLE 18 REMEDIES AND DAMAGES............................................................   57
           --------------------
ARTICLE 19 RIGHT TO CURE; FEES AND EXPENSES................................................   60
           --------------------------------
ARTICLE 20 LANDLORD REPRESENTATIONS AND COVENANTS; APPROVALS...............................   62
           -------------------------------------------------
ARTICLE 21 END OF TERM.....................................................................   64
           -----------
ARTICLE 22 QUIET ENJOYMENT.................................................................   66
           ---------------
ARTICLE 23 NO SURRENDER; NO WAIVER.........................................................   66
           -----------------------
ARTICLE 24 WAIVER OF TRIAL BY JURY.........................................................   67
           -----------------------
ARTICLE 25 INABILITY TO PERFORM............................................................   67
           --------------------
ARTICLE 26 NOTICES.........................................................................   67
           -------
ARTICLE 27 RULES AND REGULATIONS...........................................................   68
           ---------------------
ARTICLE 28 BROKER..........................................................................   69
           ------
ARTICLE 29 INDEMNITY.......................................................................   69
           ---------
ARTICLE 30 TAX STATUS OF BENEFICIAL OWNERS.................................................   71
           -------------------------------
ARTICLE 31 EXTENSION PERIOD................................................................   71
           ----------------
ARTICLE 32 PURCHASE OPTIONS ON THE BUILDING................................................   75
           --------------------------------
ARTICLE 33 SIGNAGE.........................................................................   80
           -------
ARTICLE 34 ARBITRATION.....................................................................   71
           -----------
ARTICLE 35 SECURITY DEPOSIT................................................................   81
           ----------------
ARTICLE 36 MISCELLANEOUS...................................................................   85
           -------------
ARTICLE 37 CONDITIONS PRECEDENT............................................................   89
           --------------------
ARTICLE 38 ASSOCIATION DECLARATION.........................................................   91
           -----------------------
ARTICLE 39 EXPANSION OPTIONS...............................................................   92
           -----------------
</TABLE>

                                        i

<PAGE>

                                    EXHIBITS
                                    --------

A       Description of the Land
B       Definitions
C       Design and Construction Agreement
D       Fixed Rent Schedule
E       Subordination, Non-Disturbance and Attornment Agreement
F       Cleaning Specifications
G       Letter of Credit
H       [Reserved]
I       Rules and Regulations
J       Description of Woodland Park
K       Construction Procedures
L       Specifications for HVAC, Electrical Capacity and Floor Load
M       Description of Waterview at Woodland Park
N       Agreed Area of Floors/Premises
O       Form of Memorandum of Lease
P       Form of Purchase and Sale Agreement
Q       Form of Option Agreement
R       Declarant Letter
S       [Reserved]
T       Form of ROFO PSA
U       Sample Amortization Schedule
V       Location of Generator
W       Location of Entrance Monument Sign
X       Schedule for Completion of Proffers/Development Conditions
Y       Sign Specifications for Woodland Park
Z       Conditions Landlord Must Satisfy for Issuance of Tenant's Title Policy

<PAGE>

                                  DEED OF LEASE
                                  (Waterview I)

                  THIS DEED OF LEASE (the "Lease") is made as of the 19th day of
July, 2001 ("Effective Date", which shall be the date (i) that this Lease is
fully executed by both Landlord and Tenant and (ii) that the Condition Precedent
is satisfied pursuant to Section 37 below), between TST WATERVIEW I, L.L.C.
("Landlord"), a Delaware limited liability company, having an office c/o Tishman
Speyer Properties, L.P., 8270 Greensboro Drive, Suite 810, McLean, Virginia
22102, and VERISIGN, INC. ("Tenant"), a Delaware corporation, having an office
at 21355 Ridgetop Circle, Dulles, Virginia 20166.

Landlord and Tenant hereby covenant and agree as follows:

                                    ARTICLE 1
                             BASIC LEASE PROVISIONS
                             ----------------------

PREMISES                         The entirety of the Building, Parking Garage
                                 and Land.

BUILDING                         The new thirteen (13) story Class A office
                                 building known as Waterview I, located at the
                                 intersection of the Dulles Toll Road and
                                 Centreville Road, within Woodland Park,
                                 Herndon, Fairfax County, Virginia 20171, along
                                 with related fixtures, equipment and other
                                 improvements and appurtenances, erected (or to
                                 be erected) upon the Land.

LAND                             The land (consisting of approximately 11.53
                                 acres) on which the Building and Parking Garage
                                 and certain additional exterior areas in the
                                 vicinity thereof (e.g., the plaza and seating
                                 areas) are situated, as more particularly shown
                                 on Exhibit A. Landlord represents
                                    ---------
                                 that the Land (also known as Fairfax County Tax
                                 Map Parcel 16-3((1)) 29C1) is lawfully divided
                                 from a larger parcel, such larger parcel
                                 consisting of approximately 23 acres, known as
                                 Waterview at Woodland Park as shown on the
                                 attached Exhibit M ("Waterview"). The balance
                                          ---------
                                 of Waterview (the "Adjacent Property") consists
                                 of approximately 11.92 acres and is known as
                                 Fairfax County Tax Map Parcel 16-3((1)) 29D and
                                 is legally divided from the Land. Landlord
                                 will, prior to its development, legally divide
                                 the Adjacent Property into two (2) separate
                                 parcels upon which the Waterview II office

<PAGE>

                                 building and related parking garage (or rights
                                 to the parking garage to be constructed on the
                                 Adjacent Property sufficient to satisfy
                                 applicable Requirements and the Waterview II
                                 Lease) ("Waterview II") and the Waterview III
                                 office building and related parking garage (or
                                 rights to the parking garage to be constructed
                                 on the Adjacent Property sufficient to satisfy
                                 applicable Requirements and the Waterview III
                                 Lease) ("Waterview III") (each, an "Option
                                 Property" comprised of "Option Land" and an
                                 "Option Building") will be situated, also as
                                 depicted on Exhibit M.
                                             ---------

COMMENCEMENT DATE                The date set forth in Section 2.3 below.

RENT COMMENCEMENT DATE(S)        The date(s) set forth in Section 2.3 below.

EXPIRATION                       The last day of the one hundred thirty-second
                                 (132/nd/) full calendar month after the Rent
                                 Commencement Date with respect to the last
                                 Floor delivered to Tenant (the "Last Rent
                                 Commencement Date"), subject to Sections 21 and
                                 31 (concerning Extension Periods and a
                                 Surrender Term).

TERM                             The period specified in Section 2.3 below.

PERMITTED USES                   Office and accessory purposes, and such other
                                 uses incidental or ancillary to general office
                                 use consistent with the operation of Comparable
                                 Buildings (which may include some
                                 telecommunications and call center functions,
                                 data center functions and in-house food service
                                 functions, as well as an exercise facility, a
                                 childcare facility, and a conference and/or
                                 training facility). Landlord represents that
                                 the Land is currently zoned PDC under the
                                 Fairfax County Zoning Ordinance. Tenant shall
                                 be responsible for obtaining and maintaining
                                 required permits, if any, for childcare,
                                 exercise, conference, training and food service
                                 operations. conference, training and food
                                 service operations.

TENANT'S PROPORTIONATE           A fraction, the numerator of which is the
SHARE                            Agreed Area of the Premises, and the
                                 denominator of which is the Agreed Area of the
                                 Building. Tenant's Proportionate Share as of
                                 the date of execution of this Lease is one
                                 hundred percent (100%), based on both the
                                 Building and the

                                       -2-

<PAGE>

                                 Premises having a total rentable area of
                                 404,665 square feet. References in this Lease
                                 to Tenant being the "100% tenant" or "leasing
                                 100%" or "sole tenant" or "100% of the Agreed
                                 Area of the Building" words of similar
                                 construction or import shall be deemed to mean
                                 that Tenant is leasing (as opposed to
                                 occupying) 100% of the rentable area of the
                                 Building that is devoted to office use.

AGREED AREA OF THE BUILDING      Four Hundred Four Thousand Six Hundred Sixty
                                 Five (404,665) rentable square feet, as
                                 measured in accordance with the BOMA Standard
                                 (assuming the dimensions of the Building are
                                 consistent with the Plans and Specifications).
                                 The "Agreed Area of the Premises" also is Four
                                 Hundred Four Thousand, Six Hundred Sixty-Five
                                 (404,665) rentable square feet, as measured in
                                 accordance with the BOMA Standard (assuming the
                                 dimensions of the Building are consistent with
                                 the Plans and Specifications). The "Agreed Area
                                 of each Floor", as measured in accordance with
                                 the BOMA Standard, is set forth on Exhibit N.
                                                                    ---------

FIXED RENT                       (i) For the period commencing on the first Rent
                                 Commencement Date and ending on the last day of
                                 the first Lease Year, both dates inclusive,
                                 twenty-one and 00/100 Dollars ($21.00) per
                                 annum per rentable square foot of (A) prior to
                                 delivery of all Floors pursuant to Section 2.3
                                 hereof, the Agreed Area of the Floor(s)
                                 delivered to Tenant pursuant to Section 2.3
                                 hereof and for which the applicable Rent
                                 Commencement Date has occurred, and (B)
                                 following the delivery of all Floors pursuant
                                 to Section 2.3 hereof, the entire Agreed Area
                                 of the Premises; and (ii) Commencing on the
                                 first day of the second Lease Year, and on the
                                 first day of each Lease Year thereafter through
                                 the Initial Term and any Surrender Term (with
                                 Fixed Rent for any Extension Period being
                                 determined in accordance with Section 31.1
                                 hereof) the Fixed Rent (monthly, annual and per
                                 rentable square foot) shall be increased as set
                                 forth in Exhibit D.
                                          ---------

ADDITIONAL RENT                  All amounts payable by Tenant to Landlord
                                 under this Lease other than Fixed Rent.

                                       -3-

<PAGE>

RENT                             Fixed Rent and Additional Rent, collectively.

INTEREST RATE                    The lesser of (i) four percent (4%) per annum
                                 above the then-current Base Rate, or (ii) the
                                 maximum rate permitted by applicable law.

SECURITY DEPOSIT                 Initially, fourteen million ($14,000,000.00),
                                 subject to reduction under certain
                                 circumstances as specified in Section 35.

BROKER FOR TENANT                Jones Lang LaSalle Americas, Inc.

LANDLORD'S AGENT                 Tishman Speyer Properties, L.P., or any other
                                 person designated at any time and from
                                 time to time by Landlord as Landlord's Agent.

LANDLORD'S CONTRIBUTION          The product of (a) forty dollars ($40.00) and
                                 (b) the Agreed Area of the Premises. In
                                 addition, at Tenant's request, Landlord will
                                 advance additional sums to Tenant, (i.e., the
                                 Supplemental Allowance) to be amortized and
                                 added into Fixed Rent, as and to the extent
                                 provided in Section 2.2 and Exhibit C.
                                                             ---------

All capitalized terms used in the Lease without definition are defined in
Exhibit B.
---------

                                    ARTICLE 2
                              PREMISES, TERM, RENT
                              --------------------

         Section 2.1 Lease of Premises. Subject to the terms of this Lease,
                     -----------------
Landlord leases to Tenant and Tenant leases from Landlord the Premises for the
Term. Landlord and Tenant shall complete the Building and the Premises for
Tenant's occupancy in accordance with their respective obligations under the
provisions of this Lease and the Design and Construction Agreement attached as
Exhibit C.
---------

         Section 2.2 Payment of Rent.
                     ---------------

                     (a) Tenant shall pay to Landlord, without notice or demand,
and without any set-off, counterclaim, abatement or deduction whatsoever, except
as otherwise expressly set forth in this Lease, in lawful money of the United
States by wire transfer of funds to Landlord's account, as designated by
Landlord, or by check drawn upon a bank reasonably approved by Landlord, (i)
Fixed Rent in equal monthly installments, in advance, on the first (1/st/) day
of each calendar month during the Term, commencing on the initial Rent
Commencement Date, and (ii) Additional Rent, at the times and in the manner set
forth in this Lease.
                     (b) Provided no uncured Material Default shall then exist
under this Lease, Tenant shall have the right to require Landlord to advance to
Tenant up to a maximum aggregate amount of $10.00 multiplied by the Agreed Area
of the Premises (the "Supplemental Allowance"). Such sum shall be elected and
used by Tenant in its

                                       -4-

<PAGE>

sole discretion in accordance with Paragraph C.2 of the Design and Construction
Agreement attached as Exhibit C. The amount of the Supplemental Allowance Tenant
                      ---------
elects to draw shall be treated as an assumed loan, which shall be fully
amortized over the Initial Term in one hundred thirty-two (132) equal monthly
payments. Tenant shall pay to Landlord, as an addition to Fixed Rent (including
without limitation for purposes of determining damages, if any under Section
19.2) but not escalated with Fixed Rent, beginning with the first full month of
the first Lease Year (if such amount can be calculated by such date) the monthly
amortized amount of the Supplemental Allowance together with interest on the
outstanding balance of the Supplemental Allowance at a fixed annual rate equal
to twelve percent (12%) per annum. If the first full calendar month of the first
Lease Year has already occurred, or any other months have already occurred, as
of the date such amount is calculated, Tenant shall pay all monthly amortization
payments which correspond to months that have already elapsed at the time of its
first monthly payment. In the event this Lease shall terminate for any reason
prior to the natural expiration of the Term, the entire then unamortized portion
of the Supplemental Allowance shall be due and payable to Landlord as a part of
Rent. Attached as Exhibit U is a sample, non-binding schedule of payments that
                  ---------
would be required assuming Tenant draws the maximum aggregate amount of the
Supplemental Allowance in one lump sum on the date specified in Exhibit U. The
                                                                ---------
parties agree that this Lease will be amended within thirty (30) days after the
date on which the Supplemental Allowance is fully drawn but only to reflect the
actual schedule of repayments by amending said Exhibit U. In the event Tenant
                                               ---------
exercises Extension Options that contemplate a continuation of the existing
terms and conditions, such amortization will be eliminated from Rent payments
(but the failure to repay the Supplemental Allowance in full as of the end of
the Initial Term will be a default hereunder, subject to applicable notice and
cure rights). Tenant may, from time to time throughout the Initial Lease Term,
prepay in full and without penalty, the unamortized principal balance of amounts
amortized into Fixed Rent as aforesaid, provided (i) Tenant shall give Landlord
thirty (30) days prior notice of such prepayment, (ii) Tenant shall include with
any such prepayment the amount of accrued but unpaid interest, and (iii) the
parties will promptly enter into an amendment to this Lease adjusting the Fixed
Rent as may be necessary to reflect the effect of any such prepayment. Upon
receipt of the entire unamortized amount of the Supplemental Allowance, Landlord
shall confirm the payoff of the Supplemental Allowance in writing to Tenant.

         Section 2.3 Delivery of Premises; Rent Commencement Date. Landlord
                     --------------------------------------------
shall deliver to Tenant the Building in accordance with the terms of this Lease
and the Design and Construction Agreement.

                     (a)  (1)   The "Commencement Date" shall be the date that
Landlord delivers possession of the entire Premises to Tenant with the Standard
Base Building Work Substantially Completed and with all Floors in Floor Ready
Condition, which Landlord shall cause to occur not later than March 1, 2002 (the
"Outside Date"). If Landlord fails to so deliver the Premises by the Outside
Date, then, provided no uncured Material Default shall then exist and Tenant has
previously given notice to Landlord that Tenant is ready to commence the Initial
Installations together with the Plans and Specifications therefor (subject to
Landlord Delay)), then, in addition to the

                                       -5-

<PAGE>

Rent Commencement Date postponement pursuant to Section 2.4, Tenant shall
receive an abatement of Rent for each day from and after the Outside Date until
the Premises is so delivered. In addition, if such delivery does not occur prior
to September 1, 2002 (the "Super Outside Date") and no uncured Material Default
shall then exist and Tenant has given the notice described in the immediately
preceding sentence, then Tenant shall have the right to terminate this Lease by
delivering written notice of the exercise of such right to Landlord within five
(5) Business Days after the Super Outside Date. If such termination right is not
timely exercised by Tenant, such right shall thereafter lapse and be of no
further force or effect. If this Lease is terminated pursuant to this Section,
then neither party shall have any further obligations or liability hereunder to
the other party; provided, however, that within ten (10) Business Days after
receipt of such notice of termination from Tenant, Landlord shall (A) refund any
and all security deposits, advance rent and other sums previously deposited by
Tenant in accordance with the provisions of this Lease and (B) pay to Tenant all
actual out-of-pocket costs reasonably incurred by Tenant in connection with the
negotiation of this Lease (and related documents) and Tenant's planned move to
the Premises. Notwithstanding the foregoing, neither the Outside Date nor the
Super Outside Date shall be extended on account of Unavoidable Delay or Landlord
Delay, but each such date shall be extended on a day-for-day basis for each day
Substantial Completion and delivery is delayed solely as a result of any Tenant
Delay.

                                 (2)   In addition to the Standard Base Building
Work, Landlord shall complete the remainder of the Base Building Work as and
when required under this Lease and the Design and Construction Agreement.

                           (b)   The "Rent Commencement Date(s)" shall be
determined on a Floor-by Floor basis as follows: (i) with respect to Floors 8
through 13 ("Phase One"), comprising approximately 191,162 rentable square feet,
the "Rent Commencement Date" for each Floor shall be the earlier of (a) December
1, 2002 (as extended, on a day-for-day basis, by each day of Landlord Delay) or
(b) the date Tenant commences business operations on such Floor; and (ii) with
respect to Floors 1 through 7 ("Phase Two"), comprising approximately 213,503
rentable square feet, the "Rent Commencement Date" for each Floor shall be the
earlier of (a) August 1, 2003 (as extended, on a day-for-day basis, by each day
of Landlord Delay), or (b) the date Tenant commences business operations on such
Floor. Tenant shall have no obligation to pay Rent (or any utilities or other
services or charges to the extent provided in the Design and Construction
Agreement) as to any Floor prior to the Rent Commencement Date for that Floor.
If a Rent Commencement Date shall occur on a date other than the first (1st) day
of any calendar month, Tenant shall pay to Landlord on the Rent Commencement
Date, with respect to the Floor or Floors delivered on such Rent Commencement
Date, a sum equal to Fixed Rent for such month for such Floor or Floors
multiplied by a fraction, the numerator of which shall be the number of calendar
days in the period from such Rent Commencement Date to the last day of the month
in which the Rent Commencement Date occurred, both dates inclusive, and the
denominator of which shall be the number of calendar days in such month. Any
Additional Rent payable with respect to such partial month shall be payable by
Tenant within thirty (30) days following receipt of an invoice from Landlord.

                                       -6-

<PAGE>

                     (c)   The "Term" of this Lease shall commence on the
Commencement Date and shall expire on the Expiration Date. For purposes of this
Lease: (1) the "Term" or "Lease Term" shall mean the Initial Term and, if
applicable, any exercised Extension Periods or Surrender Term; (2) the initial
fixed term of this Lease (exclusive of any exercised Extension Periods or
Surrender Term) is sometimes referred to herein as the "Initial Term"; and (3)
the Extension Periods (exclusive of the Initial Term) are sometimes each
referred to herein as an "Extension Period" and collectively as the "Extension
Periods".

                     (d)   Provided no uncured Material Default shall then
exist under this Lease, and Tenant has exercised its right to lease space in
Waterview II or Waterview III pursuant to that certain Option Agreement of even
date herewith between Landlord and Tenant (the "Option Agreement"), Tenant shall
have the option, not later than the date Tenant executes the lease document for
such additional space, to extend the then-current Term of this Lease to be
coterminous with the expiration of the last delivered phase in such Option
Building. In such event, the Fixed Rent for any such extension beyond the
initial Expiration Date will be at FMR. The determination of FMR will occur
eighteen (18) months prior to the Expiration Date (i.e., as if Tenant had
exercised its Extension Option hereunder), in accordance with the provisions of
Section 31 hereof. Tenant's election to exercise the Extension Option shall be
irrevocable once exercised by Tenant.

         Section 2.4 Landlord's Delay. If the Floors are not delivered in Floor
                     ----------------
Ready Condition or the Premises is not Substantially Completed by the dates
prescribed for in this Lease and the Design and Construction Agreement, then, in
either event, to the extent such delay is not caused by a Tenant Delay, the Rent
Commencement Date and Tenant's obligation to pay Rent shall be delayed until the
Floor Ready Condition and Substantial Completion occurs on a day-for-day basis,
by each day of such delay.

         Section 2.5 Interest. If Tenant shall fail to pay any installment or
                     --------
other payment of Rent when due, or if Landlord shall fail to make any payment of
a monetary obligation hereunder to Tenant when due, at the non-defaulting
party's option interest shall accrue on such installment or payment as a late
charge, from the date such installment or payment became due until the date paid
at the Interest Rate.

                                    ARTICLE 3
                                USE AND OCCUPANCY
                                -----------------

         Section 3.1 (a) Permitted Uses. The Premises shall be used and occupied
                         --------------
for the Permitted Uses and for no other purpose. Tenant shall not use or occupy
or permit the use or occupancy of any part of the Premises in a manner
constituting a Prohibited Use.

                     (b) Licenses and Permits. Tenant, at its expense, shall
                         --------------------
procure or cause to be procured and maintain or cause to be maintained and
comply or cause to be complied with the terms and conditions of all licenses and
permits required for the

                                       -7-

<PAGE>

lawful conduct of its Permitted Uses in the Premises. The foregoing
notwithstanding, Landlord shall be responsible for procuring any and all
licenses or permits needed in connection with completion of the Base Building
Work and, as part of Substantial Completion of the Base Building Work, the
issuance of a final non-residential use permit (core and shell only) for the
Base Building and all other components of the Premises (other than the Initial
Installations).

                     (c)  Use of Roof. Notwithstanding anything to the contrary
                          -----------
in this Section 3.1, Tenant shall have the right, at no additional cost, to
access and use the roof of the Building for the installation, use, maintenance,
repair and replacement of various communication, HVAC and/or other equipment
(collectively, "Communications Equipment") subject only to the Association
Declaration and the following:

                          (i)    in the event such installation requires Tenant
to make any penetration in the roof or perform any other roofing work, such
penetrations shall be made only in the manner designated in writing by Landlord,
acting reasonably;

                          (ii)   any installation work (including any roof
penetrations or other roofing work) shall be performed by Tenant at Tenant's
sole cost and expense and by a roofing contractor reasonably approved by
Landlord and shall be accomplished in a manner which will not invalidate or
impair any roof warranties;

                          (iii)  Tenant shall promptly pay all taxes and license
fees imposed by any federal, state or local governmental agency or authority in
connection with the installation, operation and maintenance of any
Communications Equipment;

                          (iv)   Tenant shall secure any necessary  permits,
and the installation and use of Communications Equipment shall comply with all
Requirements (including any zoning restrictions) and Tenant shall be solely
liable for the cost of such compliance;

                          (v)    At the end of the Term, Tenant shall remove
such Communications Equipment and repair the Premises, including repair the
roof, in accordance with Section 5.3;

                          (vi)   Tenant shall install screening as may be
required by the Association Declaration to reasonably obscure the location of
Communications Equipment;

                          (vii)  Any proposed installation of Communications
Equipment shall be completed in accordance with Article 5 hereof; and
                                                ---------

                          (viii) Tenant shall not assign or sublet or grant any
use rights to the roof of the Building other than incidental to a permitted
assignment or subletting pursuant to Article 15 hereof.
                                     ----------

Tenant's rights hereunder shall be exclusive (as to size and location) if Tenant
is the sole office tenant in the Building. If Tenant is not the sole office
tenant, then Tenant's

                                       -8-

<PAGE>

right shall be non-exclusive but (i) with respect to size, shall be pro rata
based on applicable proportionate shares of the tenants involved, and (ii) with
respect to location, shall be "grand-fathered" (i.e., Tenant shall not be
obligated to relocate any such equipment once installed) unless Tenant is
leasing less than 50% of the Agreed Area of the Building. Except to the extent
set forth in this Lease or the Design and Construction Agreement, Landlord makes
no warranty with respect to the weight-bearing capacity of the roof, and the
cost of any additional structural support which might be required for the
Communications Equipment shall be Tenant's sole responsibility.

                  (d)   Cabling.  Tenant shall have the right to install
                        -------
below-grade fiber optic and other cabling on the Land, and Landlord shall grant
(and cause its Affiliates to grant) Tenant (in recordable form) such rights to
such other portions of Waterview (and Landlord shall use reasonable efforts to
cause its Affiliates to grant Tenant (in recordable form) such rights to other
portions of Woodland Park), as are reasonably required to provide for
interconnectivity among all buildings leased by Tenant or its Affiliates at
Woodland Park, subject to Landlord's reasonable approval of the location and
method of installation thereof. At Tenant's sole cost and expense, Landlord
agrees to grant, or cause its Affiliates to grant (in recordable form), such
easements as may be necessary in conjunction therewith, which easements shall be
in form and substance reasonably acceptable to Landlord and Tenant.

                  (e)   Supplemental Generators.  If Tenant leases 50% or more
                        -----------------------
of the Agreed Area of the Building, Tenant shall have the right, as part of the
Initial Installations or otherwise, to install at its sole cost and expense not
more than three (3) supplemental/emergency generators and supporting equipment
in the Parking Garage or on the Land, subject to Landlord's reasonable approval
of the location and method of installation thereof, and otherwise in accordance
with the applicable requirements of Article 5 and criteria substantially
                                    ---------
similar to those set forth in Section 3.1(c)(iii) and (iv), above. Such
generator shall constitute a Specialty Alteration. Landlord shall provide the
area designated on Exhibit V in its "as-is, where-is" condition for the
                   ---------
installation of the generator(s) which shall be completed in a manner mutually
and reasonably agreed upon by Landlord and Tenant. Tenant shall, at its sole
expense, obtain any and all necessary licenses, approvals, permits, etc.,
necessary for the generator pad(s) and enclosures for the generator(s).

                  (f)   Any work described in Section 3.1 may be paid for or
reimbursed out of the Construction Allowance or Supplemental Allowance or
Lock-Out Allowance (as defined below).

     Section 3.2  [Intentionally Deleted.]
                  ----------------------

     Section 3.3  Parking.
                  -------

                  (a)   Subject to and in accordance with the terms of the Base
Building Construction Documents, Landlord shall construct (i) a multi-level
parking structure (the "Parking Garage") which shall provide a minimum of 1,574
spaces and (ii) an additional 37 spaces on the Land adjacent to the Building
(such 1,611 spaces, in

                                       -9-

<PAGE>

total, subject only to a de minimis change in the number of spaces required by
the Requirements, "Tenant's Parking Allocation") for the use of Tenant's agents,
employees and visitors at no extra charge throughout the Term. The entire
Parking Garage and the surface parking on the Land shall be for Tenant's
exclusive use for so long as Tenant is leasing the entire Agreed Area of the
Building. If Tenant is not leasing 100% of the Agreed Area of the Building,
space in the Parking Garage and the surface parking on the Land shall be shared
on a pro rata basis (based upon rentable square footage in the Building) with
other tenants of the Building. Tenant shall at all times have the exclusive
right to designate up to its entire Parking Allocation as reserved parking for
Tenant and to secure same by gating and the use of security key cards or other
means, and may utilize stacked or valet parking in the Parking Garage; provided,
however, that all parking spaces designated by Tenant for use on an exclusive
basis and secured through gating shall be designated from the uppermost levels
of the Parking Garage down in order to facilitate access to and from non-gated
areas of the Parking Garage by other tenants not being leased by Tenant therein.
Throughout the Term, as may be extended, the Parking Garage shall be managed (at
no additional charge) by the party managing the Building, or by such other party
as Landlord and Tenant, so long as Tenant is leasing not less than 75% of the
Agreed Area in the Building, may reasonably agree upon.

                  (b)   If Tenant exercises its Primary Purchase Option under
this Lease, then Landlord shall convey unencumbered fee simple title to the
Parking Garage to Tenant, a Tenant Affiliate or to any designee of Tenant
identified in accordance with Section 32.1(e). In addition (i) during any period
in which Landlord or a Landlord Affiliate owns title to the Building, Landlord
or such Landlord Affiliate will continue to hold title to the Parking Garage
(and related land) and (ii) Landlord will not sell the Building or the Parking
Garage to a party other than Tenant prior to the expiration of Tenant's Primary
Purchase Option.

                                    ARTICLE 4
                            CONDITION OF THE PREMISES
                            -------------------------

     Section 4.1  Condition.
                  ---------

                  (a)   Landlord shall complete, as and when required under this
Lease and the Design and Construction Agreement, the Base Building Work (which
includes, without limitation, the Punch List Items, Latent Defects, the Required
Improvements, and any other item expressly designated in this Lease and the
Design and Construction Agreement as a Landlord construction obligation). While
Landlord is doing any work at the Premises, Landlord shall do so in compliance
with all Requirements, the terms of this Lease and the Design and Construction
Agreement, and, if Tenant is in occupancy of any portion of the Building, in
accordance with the construction rules attached as Exhibit K. Any work to be
                                                   ---------
performed by or on behalf of Tenant in connection with Tenant's initial
occupancy of the Premises shall be referred to herein as the "Initial
Installations" and shall be completed in accordance with the terms of the Design
and Construction Agreement. Tenant shall be responsible for

                                      -10-

<PAGE>

completing the Initial Installations. Except for the completion of the Base
Building Work and provision of Landlord's Contribution and Supplemental
Allowance, Landlord shall have no obligation to perform any work, supply any
materials, incur any expense (except as expressly set forth in this Lease or the
Design and Construction Agreement) or make any Alterations to the Premises to
prepare it for Tenant's initial occupancy. Except with respect to completion of
any then unfinished item of Base Building Work (including, without limitation,
the Punch List Items, the repair of Latent Defects, and subject to warranty
items pursuant to Section 4.1(c) of this Lease), Tenant's occupancy of any part
of the Premises shall be conclusive evidence, as against Tenant, that Tenant has
accepted possession of that portion of the Premises in its then-current
condition and that such portion is in a good and satisfactory condition.

                  (b)   During the period from the Commencement Date to the
Rent Commencement Date for a particular Floor: (i) Tenant will not be charged
for any reasonable and customary amounts (based upon normal usage for buildout
purposes) for parking, hoisting (excluding external hoisting), electrical
services, services of a reasonably available building manager to oversee and
operate Building Systems pursuant to Section 11.1 of this Lease, heating and
cooling, water, use of elevators, security and any other utilities or services
related to construction activity; and (ii) Landlord will provide reasonably
sufficient construction parking for Tenant's construction and related personnel
(without charge), the location and number of which will be reasonably
coordinated with Landlord. Landlord agrees to allow Tenant access to the
Premises prior to Substantial Completion or the delivery of the Floors in Floor
Ready Condition, without any obligation to pay Rent or other charges, as is
reasonably practicable to allow Tenant to commence construction of the Initial
Installations (which shall include, without limitation, the installation of
phone and data cabling, supplemental security systems, and audio/visual systems
in the Premises to the extent not included within the Base Building Work).
Tenant also shall have the right on an ongoing basis throughout the process of
constructing the Building, during normal working hours, to have access to the
Premises for purposes of observation and inspection during the performance of
the Base Building Work. To the extent any entry of Tenant within the Premises
prior to Substantial Completion interferes (other than in a de minimis manner)
with the orderly progress of construction of Base Building Work, Tenant shall
cause such interference to cease immediately; and any delays in the Substantial
Completion of the Base Building Work caused by such interference shall
constitute a Tenant Delay. Access for the aforesaid purposes shall not be deemed
to constitute possession or occupancy.

                  (c)   Landlord shall warrant each portion of the Base
Building Work for a period of one (1) year after Substantial Completion thereof.
Landlord agrees to promptly commence and diligently pursue the correction of all
Punch List Items as soon as reasonably possible, and, subject to Unavoidable
Delays, to complete the correction of all Punch List Items within forty-five
(45) days after the Punch List is finalized. The provisions of Section 19.2 of
this Lease shall apply to any default by Landlord with respect to this
obligation (subject to the notice and cure periods set forth in Section 19 of
this Lease). For a period of one (1) year after Substantial Completion of the
Base Building Work, Landlord further agrees to repair or replace (or to cause
the

                                      -11-

<PAGE>

repair or replacement of) any Latent Defects in the Base Building Work or in the
Building Systems or Base Building (i.e., structure) as soon as reasonably
practicable after Tenant provides notice thereof to Landlord. Unless otherwise
required of Landlord pursuant to the provisions of this Lease, Landlord shall
have no obligation to repair defects in any such work which are detected more
than one (1) year after the date of Substantial Completion. The foregoing shall
not affect, however, any of the general repair covenants set forth in this
Lease, nor shall it apply to limit the warranty period provided for by the
manufacturer or supplier with respect to any equipment incorporated into the
Building or Premises, nor the warranty period otherwise provided for under the
terms of the Base Building construction contract if such warranty period exceeds
one (1) year. Within ninety (90) days after Substantial Completion of the Base
Building Work, Landlord will provide to Tenant a full set of construction
drawings for the Base Building Work, as marked by the applicable contractor(s)
to reflect actual as-built improvements incorporated therein to the extent the
same differ from those reflected in the original construction documents.
Landlord agrees to cooperate with Tenant and to provide Tenant with construction
drawings for the Base Building Work, as marked by applicable contractor(s) to
reflect actual as-built improvements, as the same are required by Tenant for
Tenant's design work. In all events, not later than February 1, 2002, Landlord
will provide to Tenant a full set of construction drawings for the Base Building
Work, as marked by the applicable contractor(s) to reflect actual as-built
improvements incorporated therein to the extent the same differ from those
reflected in the original construction documents.

     Section 4.2  Landlord's Contribution.
                  -----------------------

                  (a)   Landlord agrees to pay to Tenant Landlord's
Contribution toward the cost of the Initial Installations, provided that as of
the date on which Landlord is required to make payment thereof (i) this Lease is
in full force and effect, and (ii) no uncured Material Default shall then exist
(except such as can be cured or satisfied by Landlord by offset against
obligations owed to Tenant).

                  (b)   In accordance with the terms and conditions of Section
2.2 of this Lease and the Design and Construction Agreement, Landlord agrees to
provide Tenant with the Supplemental Allowance to be used as specified in
accordance with Section C.2 of the Design and Construction Agreement.

                  (c)   Landlord's Contribution and the Supplemental Allowance
shall be payable by Landlord in accordance with Section C.2 of the Design and
Construction Agreement.

     Section 4.3  No Landlord's Supervision Fee. Except as expressly provided
                  -----------------------------
for elsewhere in this Lease or the Design and Construction Agreement, Tenant
shall not be required to pay any construction supervision or other fee to
Landlord for any work or change orders in connection with the Initial
Installations or the Base Building Work.

                                      -12-

<PAGE>

                                    ARTICLE 5
                                   ALTERATIONS
                                   -----------

      Section 5.1 Tenant's Alterations.
                  --------------------

                  (a)   Tenant shall be entitled to make alterations, additions
or other physical changes in or about the Premises (collectively,
"Alterations"), without Landlord's prior consent (but where consent is required,
the scope of same shall be defined in the next succeeding sentence), provided
that such proposed Alterations: (i) are decorative (such as painting, wall
covering and carpeting) ("Decorative Alterations"), (ii) affect only the
Building, (iii) do not adversely affect the non-residential use permit issued
for the Building, and (iv) do not change or alter any surface parking, except to
a de minimis extent. Landlord's prior consent shall be required for any
Alterations not meeting the foregoing criteria, which consent shall be within
Landlord's sole discretion for Alterations that are structural or affect the
Building's facade, and which consent shall not be unreasonably withheld,
conditioned or delayed for any other such Alterations (including those that
affect the Building Systems, the Parking Garage and landscaping). If Landlord
fails to respond to any request to approve any plans or contractors within
eleven (11) Business Days, then the request shall be deemed approved. The
Initial Installations and each subsequent Alteration, whether temporary or
permanent in character, made by Landlord or Tenant in or upon the Premises shall
become Landlord's Property (excluding FF&E (which FF&E shall include trade
fixtures and systems furniture, but shall exclude true real estate fixtures),
any generator, any uninterrupted power source, and any free-standing computer
HVAC equipment, and any other item so designated by Landlord at the time of
Landlord's approval), and shall remain upon the Premises at the expiration or
termination of this Lease without compensation to Tenant, subject to Section
5.3.

                  (b)   Plans and Specifications.  Where Landlord's approval is
                        ------------------------
required, prior to making any Alterations affecting structure, Building Systems,
exterior elements or which require the issuance of a building permit ("Major
Alterations"), Tenant, at its expense, shall (i) submit to Landlord for its
written approval, reasonably detailed plans and specifications (including, where
relevant and appropriate, layout, architectural, mechanical, electrical,
plumbing, sprinkler and structural drawings) of each proposed Alteration, and
with respect to any Alteration affecting any Building System, Tenant shall
submit proof that the Alteration has been designed by, or, provided such party
is readily available to perform such review, reviewed and approved by,
Landlord's designated engineer for the affected Building System (the reasonable
cost of such review and approval to be at Tenant's expense), (ii) obtain all
permits, approvals and certificates required by any Governmental Authorities,
and (iii) furnish to Landlord duplicate original certificates of worker's
compensation (covering all persons to be employed by Tenant, and Tenant's
contractors and subcontractors in connection with such Alteration) and
comprehensive public liability (including property damage coverage) insurance
and Builder's Risk coverage (issued on a completed value basis), as required by
Article 12 hereof. Upon Tenant's request, Landlord shall reasonably cooperate
----------
with Tenant in obtaining any permits, approvals or certificates required to be
obtained by Tenant in connection with any permitted Alteration (if the
provisions of the

                                      -13-

<PAGE>

applicable Requirement require that Landlord join in such application), provided
Landlord shall incur no cost or expense in connection therewith.

                  (c)   Governmental Approvals.  Upon completion of any
                        ----------------------
Alterations requiring permits, Tenant, at its expense, shall promptly obtain
certificates of final approval of such Alterations required by any Governmental
Authority and shall furnish Landlord with copies thereof, together with
"as-built" plans and specifications for such Alterations.

      Section 5.2 Manner and Quality of Alterations. All Alterations shall be
                  ---------------------------------
performed (a) in a good and workmanlike manner, (b) substantially in accordance
with the plans and specifications (if any) and by contractors reasonably
approved by Landlord, (c) excepting Decorative Alterations, under the
supervision of a licensed architect reasonably satisfactory to Landlord, and (d)
in compliance with all Requirements, the terms of this Lease, the construction
rules attached as Exhibit C, Schedule C-5 ("Construction Procedures") and the
                  -----------------------
Rules and Regulations. All materials and equipment to be used in the Premises
shall be of new or like new quality.

      Section 5.3 Removal of Tenant's Property. Tenant's Property shall be
                  ----------------------------
and remain the property of Tenant and Tenant may remove the same at any time on
or before the Expiration Date. On or prior to the Expiration Date, Tenant shall,
as may be directed by Landlord pursuant to this Section 5.3, at Tenant's
expense, remove Specialty Alterations. Tenant shall repair and restore, in a
good and workmanlike manner, any damage to the Premises caused by Tenant's
removal of any Specialty Alterations or Tenant's Property or by the closing of
any slab penetrations, and upon default thereof after ten (10) days' prior
written notice, Tenant shall reimburse Landlord, on demand, for Landlord's
reasonable cost of repairing and restoring such damage. Any Specialty
Alterations required to be removed pursuant to this Section 5.3 or Tenant's
Property not so removed shall be deemed abandoned and Landlord may remove and
dispose of same, and repair and restore any damage caused thereby, at Tenant's
reasonable cost and without accountability to Tenant unless the same are removed
within five (5) Business Days after a written notice from Landlord to Tenant
notifying Tenant that Tenant has failed to remove such items of personal
property from the Premises and that the same will be deemed abandoned if not
removed within five (5) Business Days thereafter. This Section 5.3 shall survive
the expiration or earlier termination of this Lease. At least sixty (60) days
prior to the expiration of the Term, Tenant shall deliver to Landlord a written
notice setting forth which Specialty Alterations it intends to remove and
Landlord shall, within thirty (30) days of receipt of such notice, identify any
additional Specialty Alterations which must be removed and which must stay. No
Specialty Alteration shall be required to be removed by Tenant unless, at the
time of Tenant's request for Landlord's consent, Landlord designated such
proposed Alteration as a Specialty Alteration to be removed (with Landlord being
required to so designate any Specialty Alterations completed as part of the
Initial Installations at the time it approves the Plans and Specifications or
changes thereto).

      Section 5.4 Mechanic's Liens. Tenant, at its expense, shall discharge
                  ----------------
any lien or charge filed against the Premises in connection with any work
claimed or determined

                                      -14-

<PAGE>

in good faith by Landlord to have been done by or on behalf of, or materials
claimed or determined in good faith by Landlord to have been furnished to,
Tenant, within twenty (20) days after Tenant's receipt of notice thereof by
payment, filing the bond required by law, or otherwise in accordance with law.

         Section 5.5 Tenant's Costs. Tenant shall pay to Landlord or its
                     --------------
designee, within thirty (30) days after demand, all reasonable out-of-pocket
costs actually incurred by Landlord in connection with Tenant Alterations,
including costs reasonably incurred in connection with (a) Landlord's review of
the Alterations (including review of requests for approval thereof) and (b) the
provision of Building personnel during the performance of any Alteration
required by trade union policy, to operate elevators or otherwise to facilitate
Tenant's Alterations. The foregoing shall not apply with respect to the Initial
Installations. Landlord shall not charge any oversight or other construction
supervision fee for any Alterations.

         Section 5.6 Tenant's Equipment. Tenant shall provide notice to Landlord
                     ------------------
prior to moving any heavy machinery, heavy equipment, heavy freight, bulky
matter or bulky fixtures (collectively, "Equipment") into or out of the
Building. The term "Equipment" shall not include normal and customary deliveries
made to the Building in connection with the conduct of Tenant's business in
accordance with the Permitted Uses. If such Equipment requires special handling,
Tenant agrees (a) to employ only persons holding all necessary licenses to
perform such work and (b) all work performed in connection therewith shall
comply with all applicable Requirements. The agreements set forth in this
Section 5.6 shall survive the expiration or earlier termination of this Lease.

         Section 5.7 Legal Compliance. The approval of plans or specifications
                     ----------------
for, or consent by Landlord to the making of, any Alterations does not
constitute Landlord's agreement or representation that such plans,
specifications or Alterations comply with any Requirements or the
non-residential use permit issued for the Building. Landlord shall have no
liability to Tenant or any other party in connection with Landlord's approval of
any plans and specifications for any Alterations, or Landlord's consent to
Tenant's performing any Alterations. If as the result of any Alterations made by
or on behalf of Tenant, Landlord is required to make any alterations or
improvements to any part of the Building in order to comply with any
Requirements, Tenant shall pay all actual costs and expenses incurred by
Landlord in connection with such alterations or improvements.

                                    ARTICLE 6
                                   FLOOR LOAD
                                   ----------

         Tenant shall not place a load upon any Floor that exceeds the per
square foot "live load" limitations set forth in Exhibit L. In the event that
                                                 ---------
Tenant intends to install Equipment weighing in excess of seventy-five percent
(75%) of the Building's "live load" limitations as so specified, Tenant shall
consult with Landlord regarding the proposed location of such Equipment.

                                      -15-

<PAGE>

                                    ARTICLE 7
                                     REPAIRS
                                     -------

     Section 7.1  Landlord's Repair and Maintenance.
                  ---------------------------------

                  (a)  Landlord shall operate, maintain and, except as provided
in Section 7.2 hereof, make all necessary repairs and replacements and perform
any maintenance to the Premises (excluding items of the Initial Installations
such as wall coverings, carpeting and the like, but including extensions of the
Building Systems such as additional sprinkler heads, VAV boxes, supplemental
HVAC units, plumbing systems and the like) in conformance with standards
applicable to first-class office buildings of comparable age and quality in the
Reston/Herndon submarket of Fairfax County, Virginia ("Comparable Buildings").
Without limiting the foregoing, Landlord's obligations hereunder shall include:
(i) the exterior of the Building and Parking Garage, together with all
landscaping and parking areas adjacent to said Building; (ii) all structural
repairs to the Building and Parking Garage, including all repairs to the
foundation, roof (except as provided for in Section 3.1(c) above), structure,
exterior walls, and common area doors and windows; (iii) electric wiring,
risers, plumbing, heating, air-conditioning and any other Building System
(including base building restrooms) serving the Premises; (iv) all Common Areas,
including the underground utility and sewer pipes of the Building (except to the
extent required to be maintained or repaired by a governmental authority); (v)
all Punch List Items, Latent Defects and Landlord's obligation for warranty
items pursuant to Section 4.1(c) of this Lease; and (vi) all other repairs,
maintenance and replacements deemed reasonably necessary for the prudent
management of the Premises or as requested by Tenant. All costs of repair and
maintenance to the Premises shall be included as Operating Expenses, unless
specifically excluded pursuant to Article 8.
                                  ---------

                  (b)  During the Term, at either party's request, Landlord and
Tenant shall meet at least twice per year to discuss matters relating to the
operation and maintenance of the Premises including the condition and operation
of the Premises. In accordance with Section 8.1, Tenant shall have the right to
review and discuss with Landlord the budgets for capital expenditures,
warranties and maintenance programs for the Premises. For so long as Tenant
leases seventy-five (75%) of the Agreed Area of the Building, in the event that
Tenant in good faith objects to any operational and maintenance procedures
implemented or proposed by Landlord as not being in compliance with the terms of
this Lease, and Landlord disagrees with Tenant's determination, the parties
agree to submit such dispute to expedited arbitration in accordance with Section
34.2 of this Lease. Upon Tenant's reasonable request, Landlord shall provide
Tenant such evidence as Tenant may reasonably request to demonstrate Landlord's
compliance with such procedures as Landlord and Tenant may mutually approve.

                  (c)  Landlord agrees to diligently  attend to any repairs or
maintenance needs brought to its attention by written notice from Tenant as soon
as reasonably practicable (but in no event shall Landlord commence such repairs
or maintenance later than five (5) Business Days (or shorter period as may be
reasonably

                                      -16-

<PAGE>

required in an emergency) thereafter or cease to pursue the completion of such
repair with diligence) and in a commercially reasonable manner calculated to
minimize to the extent possible disruption of Tenant's business activities.

     Section 7.2  Tenant's Repair and Maintenance. Tenant shall promptly, at its
                  -------------------------------
expense and in compliance with Article 5 of this Lease, make all repairs of
                               ---------
Tenant's Property and the Initial Installations not the responsibility of
Landlord pursuant to Section 7.1. All Tenant repairs shall be of a quality at
least equal to the original work or construction utilizing new or like new
construction materials and shall be made in accordance with this Lease. Tenant
shall give Landlord prompt notice of any defective condition of which Tenant is
aware in any Building System.

     Section 7.3  Failure to Repair or Maintain. If either party fails within
                  -----------------------------
the time periods required by this Lease (or such shorter period as may be
required in an emergency) to proceed with diligence to make any required repairs
or perform any maintenance, the other party may do so and (i) if Tenant has
failed to do so, all reasonable, out-of-pocket costs and expenses incurred by
Landlord on account thereof shall be charged to Tenant as Additional Rent and
(ii) if Landlord has failed to do so, upon a final, non-appealable judicial or
arbitration determination that Landlord has defaulted in such repair obligation,
all reasonable, out-of-pocket costs and expenses incurred by Tenant on account
thereof which are in excess of the amounts otherwise includable in Operating
Expenses (with consideration given to any extra costs incurred due to Tenant,
and not Landlord, not incurring same, with attendant economies of scale, in the
normal and ordinary course) shall be paid by Landlord, and, if not so paid, may
be offset against future obligations to pay Rent hereunder (as specified below).

     Section 7.4  Interruptions Due to Repairs.
                  ----------------------------

                  (a)  Landlord reserves the right to make, at Landlord's cost
except as otherwise provided in this Lease, all changes, alterations, additions,
improvements, repairs or replacements to the Building, including the Building
Systems which provide services to Tenant, as Landlord deems reasonably
necessary, provided that in no event shall the level of any Building Service
decrease in any respect (other than de minimis) from the level required of
Landlord in this Lease as a result thereof (other than minor, infrequent,
temporary fluctuations in the level of such services during the performance of
any such work by Landlord, the timing of which fluctuations shall, where
commercially reasonable, be coordinated with Tenant). Landlord shall minimize
interference with Tenant's use and occupancy of the Premises during the making
of such repairs, alterations, additions, improvements, repairs or replacements
provided that Landlord shall have no obligation to employ contractors or labor
at overtime or other premium pay rates or to incur any other overtime costs or
additional expenses whatsoever except at Tenant's sole cost and expense upon
Tenant's request. Landlord shall provide Tenant with reasonable notice of the
scope and schedule of any such work and, in the event that the completion
thereof is reasonably likely to disrupt (other than in a de minimis manner) the
operation of Tenant's business at the Premises, Landlord shall perform such work
during non-business hours. Except as expressly provided in this Lease to the
contrary, there shall be no Rent abatement or allowance to

                                       -17-

<PAGE>

Tenant for a diminution of rental value, no actual or constructive eviction of
Tenant, in whole or in part, no relief from any of Tenant's other obligations
under this Lease, and no liability on the part of Landlord by reason of
inconvenience, annoyance or injury to business arising from Landlord, Tenant or
others making, or failing to make, any repairs, alterations, additions or
improvements in or to any portion of the Building or the Premises, or in or to
fixtures, appurtenances or equipment therein.

               (b)  Notwithstanding anything to the contrary contained in this
Lease, if Tenant is unable to use the Building (or any portion, other than de
minimis, thereof) for the ordinary conduct of Tenant's business due to (a) an
interruption of an Essential Service (as hereinafter defined) resulting from
Landlord's performance of an alteration, addition, impairment, repair or
replacement to the Premises, or due to Landlord's entry into the Premises, or
for any other reason within Landlord's or its agent's reasonable control, or (b)
Unavoidable Delays, other than casualty or condemnation (which are governed by
Article 13 and Article 14, respectively), and such condition continues for a
----------     ----------
period in excess of six (6) consecutive days after (i) Tenant furnishes a notice
to Landlord (the "Abatement Notice") stating that Tenant's inability to so use
the Premises (or portion thereof) is due to such condition, and (ii) Tenant does
not actually use or occupy the Premises (or portion thereof) during such period
for the ordinary conduct of its business, then Fixed Rent, Taxes and Operating
Expenses for such portion of the Building that is both untenantable and
unoccupied (determined based upon the ratio which the square footage of such
portion of the Building), determined using the BOMA Standard bears to the Agreed
Area of the Building shall be abated on a per diem basis for the period
commencing on the date the Essential Service is interrupted and ending on the
earlier of (x) the date Tenant reoccupies such portion of the Premises for the
ordinary conduct of its business, and (y) the date on which such condition is
remedied in all material respects. "Essential Service" shall mean any Building
Service.

                                    ARTICLE 8
                          OPERATING EXPENSES AND TAXES
                          ----------------------------

     Section 8.1  Definitions. For the purposes of this Article 8, the following
     -----------  -----------                           ---------
terms shall have the meanings set forth below:

                  (a)  "Assessed Valuation" shall mean the amount the Premises
                        ------------------
is assessed for the purpose of imposition of Taxes.

                  (b)  "Operating Expenses"  shall mean the aggregate of all
                        ------------------
actual costs and expenses (and sales or use taxes or other similar taxes in the
nature of sales or use taxes, if any, thereon) paid by or on behalf of Landlord
(whether directly or through independent contractors) in connection with the
management, operation, safety, repair, and maintenance of the Premises:
including (i) casualty, liability and other insurance premiums for insurance
required or permitted under this Lease; (ii) the cost of electricity, gas, oil,
steam, water, air conditioning and other fuel and utilities (to the extent
Tenant does not pay for same directly); (iii) reasonable attorneys' fees and
disbursements (but only to the extent they are incurred in connection with an
expense which is includable in

                                      -18-

<PAGE>

Operating Expenses) and auditing, management, consulting and other professional
fees and expenses reasonably necessary for Landlord to render the required
services pursuant to this Lease; and (iv) any capital expenditures (as defined
under GAAP) incurred by Landlord to meet applicable Requirements (which are not
in effect on the date the Premises are Substantially Completed) but excluding
those due to Landlord's negligence or willful misconduct, or with the consent of
Tenant, which shall not be unreasonably withheld, conditioned or delayed (except
in the last eighteen (18) months of the Term), incurred by Landlord in good
faith for the purpose of reducing Operating Expenses, subject to the conditions
described below in this Section 8.1(b). Such capital expenditures shall be
amortized on a straight-line basis over the useful life of the improvement being
amortized (with interest accruing per annum on the unamortized portion thereof
at the Base Rate in effect at the time such improvements are Substantially
Completed). A capital improvement shall be included in Operating Expenses only
if it (1) actually results in savings in such year (as for example, expenditures
for a labor-saving improvement) in which case the amount included in Operating
Expenses shall not exceed the amount of actual savings from such improvement in
the same year and/or (2) is made in order to comply with Requirements.

               (c)  Operating Expenses Exclusions. Notwithstanding and without
                    -----------------------------
limitation of the foregoing, the following costs and expenses shall be excluded
from Operating Expenses:

                    (1)  Costs incurred in connection with the construction of
the Base Building Work;

                    (2)  Costs of correcting defects in the Base Building Work,
or the initial design, construction, reconstruction or renovation of the
Premises, or equipment therein, to the extent covered by warranties or
guaranties of contractors or subcontractors or any tenant improvements;

                    (3)  Non-cash items such as depreciation, amortization,
reserves, bad debt losses and reserves therefor, or other non-cash expenses,
except for amortization of personal property used in the ordinary course of
operating and maintaining the Premises and the cost of which would be properly
included as an Operating Expense if expensed rather than amortized, except as
permitted in Section 8.1(b);

                    (4)  Interest, points, fees and principal payments on
mortgages and other debt costs, if any, or amortization on any mortgage or
mortgages or any other debt instrument encumbering the Premises;

                    (5)  Rental payments pursuant to any ground lease or master
space lease (except to the extent otherwise properly includable in Operating
Expenses provided that such payments shall not be counted more than once);

                    (6)  Expenses directly resulting from the breach of this
Lease or any other lease or agreement by Landlord, or the negligence of
Landlord, its

                                       -19-

<PAGE>

agents, contractors or employees, or other acts or omissions of tenants other
than Tenant, and any fines or penalties incurred by Landlord other than as a
result of Tenant's negligence or willful misconduct;

                    (7)  Costs for which Landlord is reimbursed by its insurance
carrier, any tenant's carrier, any tenant, any warrantor or any other third
party, and any condemnation proceeds;

                    (8)  Costs associated with the operation of the business of
the Landlord, as distinguished from the costs of operation of the Premises,
including accounting and legal matters, costs of defending any lawsuits with any
prospective or actual purchaser, ground lessor or mortgagee, costs of selling,
syndicating, financing, mortgaging or hypothecating any of Landlord's interest
in the Premises, costs of any disputes between Landlord and its employees,
disputes of Landlord with Building management, and outside fees paid in
connection with disputes with other tenants;

                    (9)  The wages of any employee of Landlord who does not
devote substantially all of his or her time to the Premises, except to the
extent such wages and benefits are reasonably, properly and equitably allocable
to time spent by such employee in directly servicing the Premises;

                    (10) Fees for services rendered by an affiliate of Landlord
to the extent such fees exceed the market rate payable for comparable services
if rendered by unrelated third parties of comparable quality, except as
pre-approved by Tenant and except that management fees shall be included in
Operating Expenses to the extent provided in Section 11.5;

                    (11) Any expenditures (whether repairs, improvements or
otherwise) that under GAAP should be treated as capital expenditures, except as
expressly permitted by Section 8.1(b);

                    (12) Fines, penalties, late payment charges and interest
arising from the negligent acts or inaction of Landlord or failure timely to
make tax and/or other payments except for such fines, penalties, late payment
charges and interest incurred after Tenant has failed to pay its Proportionate
Share of Taxes pursuant to Section 8.2, except that interest on assessments
described in clause (19) shall be included and deemed incurred as if Landlord
has elected to pay such assessments in the maximum number of permitted
installments;

                    (13) Costs of replacements or repairs for the restoration of
all or any portion of the Premises after the occurrence of a casualty;

                    (14) Legal fees, court costs and litigation related fees
(including costs or fees relative to the defense of Landlord's interest in the
Land, except for those incurred in connection with recovery under service
contracts, which shall be netted out from such recovery;

                                      -20-

<PAGE>

                    (15) Costs of repairs or replacements caused by the exercise
of any right of condemnation or eminent domain by any public or quasi-public
authority;

                    (16) Taxes other than Taxes described in Section 8.2 and
other than sales and use taxes on items the cost of which is properly included
in Operating Expenses;

                    (17) Salaries and other compensation paid to executive
employees above the grade of regional manager (including profit sharing, bonuses
and other employee benefit plans), provided, that the manager of the Building
may have responsibility for more than one building in Woodland Park, in which
case the reasonably and properly directly allocable cost of such salary and
other compensation shall be included in Operating Expenses in accordance with
clause (9) above;

                    (18) General overhead and administrative expenses (other
than accounting expenses, to the extent reasonably and properly directly
allocable to the operation of the Premises);

                    (19) Assessments to the extent paid in fewer than the
maximum permitted number of installments;

                    (20) Costs associated with any property other than the
Premises, except for those costs incurred by Landlord pursuant to the
Association Declaration, but only to the extent such costs relate, or are
attributable, to Landlord's ownership of the Premises and not to other property
owned by Landlord in Woodland Park;

                    (21) Costs to comply with Requirements to the extent such
Requirements are not being complied with as of the Commencement Date;

                    (22) Charitable and political contributions, advertising and
promotional expenditures, including costs of staging special events;

                    (23) The cost of the acquisition or installation of any
artwork, including, without limitation, any statues or paintings or electronic
artwork or advertising;

                    (24) Painting, redecorating or other work which Landlord
performs for specific tenants;

                    (25) The expenses of which are paid by such tenants; leasing
commissions, and advertising, legal, space planning and construction expenses
incurred in procuring tenants for the Building;

                                       -21-

<PAGE>

                    (26) Reserves for repairs, maintenance and replacements;

                    (27) Costs and expenses incurred by Landlord pursuant to any
provisions of this Lease which require Landlord to perform certain obligations
or services at Landlord's sole cost and expense and without recovery as an
Operating Expense;

                    (28) Any portion of any Operating Expense which is in excess
of Tenant's properly allocable or proportionate share;

                    (29) Any item of cost which Tenant is required to pay
separately pursuant to any other provision of the Lease;

                    (30) Costs of any amenity, business or activity that
generates or from which Landlord obtains income; costs of purchasing or leasing
sculpture, paintings or other art objects, except as specifically approved by
Tenant;

                    (31) More than an arms length, market rate rent, and any
other expense, for Landlord's Woodland Park management office (which shall be of
a reasonable size); and any rent or other expense for any leasing office, if
any;

                    (32) Costs of defending any lawsuits with any Mortgagees or
Lessors;

                    (33) Any amounts payable by Landlord to another tenant or
Landlord's lender by way of indemnity or damages (except direct reimbursement of
amounts incurred for costs which would be includable in Operating Expenses); and

                    (34) Any expenses associated with the Parking Garage paid
for by Tenant or any garage operator directly.

          In addition to the foregoing, all Operating Expenses shall be reduced
by all cash discounts, trade discounts or quantity discounts received by
Landlord or Landlord's Agent in the purchase of any goods, utilities or services
in connection with the prudent operation of the Premises. Landlord shall not
collect from the tenants of the Premises more than one hundred percent (100%) of
the actual costs of operating the Premises. In the calculation of any Operating
Expenses, it is understood that no expense shall be charged more than once
(whether directly or in Operating Expenses). Landlord shall equitably prorate
bills for services rendered to the Premises and to any other property owned by
Landlord or an Affiliate. Landlord shall diligently and in good faith pursue all
insurance, breach of warranty or other claims or actions that might result in a
reduction in Operating Expenses payable by Tenant. Landlord covenants to pay all
Operating Expenses and Taxes before the same become delinquent (subject to the
right to contest by law), but Landlord shall not be in default of the obligation
to pay Taxes to the extent such payment is not made due to Tenant's failure to
comply with its obligation to make the payments contemplated hereby in a timely
fashion. Any Operating Expenses relating to the Parking Garage shall be
reasonably allocated among all tenants using

                                      -22-

<PAGE>

the Parking Garage. In exercising any self help rights hereunder, if Tenant
incurs out-of-pocket costs and expenses in excess of amounts otherwise
includable in Operating Expenses, Operating Expenses shall be reduced by an
amount sufficient to give consideration to any extra costs incurred due to
Landlord not incurring such costs, with attendant economies of scale, in the
normal and ordinary course.

                  (d)  [Intentionally Deleted.]

                  (e)  "Taxes"  shall mean (i) all real estate  taxes,
                        -----
assessments, sewer and water rents, rates and charges and other governmental
levies, impositions or charges, whether general, special, ordinary,
extraordinary, foreseen or unforeseen, which may be assessed, levied or imposed
upon all or any part of the Premises, and (ii) all expenses (including
reasonable attorneys' fees and disbursements and experts' and other witnesses'
fees) reasonably incurred in contesting any of the foregoing or the Assessed
Valuation of all or any part of the Premises. Taxes shall not include (i) any
franchise, corporation, income, receipts, inheritance, estate, revenue or net
profits tax which may be assessed against Landlord or the Premises or both, (ii)
transfer taxes assessed against Landlord or the Premises or both, (iii)
penalties or interest on any late payments of Landlord, (iv) personal property
taxes of Tenant, or (v) any of the items set forth in the next succeeding
sentence, except upon the terms and conditions set forth therein, or (vi) any
items excluded from Operating Expenses in Section 8.1(c). If at any time the
methods of taxation prevailing on the date hereof shall be altered so that in
lieu of or, if of a nature customarily paid or reimbursed by tenants of
Comparable Buildings, as an addition to the whole or any part of Taxes, there
shall be assessed, levied or imposed (1) a tax, assessment, levy, imposition or
charge based on the income or rents received from the Premises whether or not
wholly or partially as a capital levy or otherwise, (2) a tax, assessment, levy,
imposition or charge measured by or based in whole or in part upon all or any
part of the Premises and imposed upon Landlord, (3) a license fee measured by
the rents, or (4) any other tax, assessment, levy, imposition, charge or license
fee however described or imposed, if imposed upon the Premises or Landlord by
reason of its ownership of the Premises, then all such taxes, assessments,
levies, impositions, charges or license fees or the part thereof so measured or
based shall be deemed to be Taxes, provided that any tax, assessment, levy,
imposition or charge imposed on income or rents from the Premises shall be
calculated as if the Premises were the only asset of Landlord.

     Section 8.2  Tenant's Tax Payment. Beginning on the Rent Commencement Date
                  --------------------
for each Floor, and continuing thereafter throughout the Term, Tenant shall pay
to Landlord Tenant's Proportionate Share of Taxes during the Term, except that,
during the Partial Term, Tenant's Proportionate Share shall be adjusted to
reflect the portion of the Building delivered to Tenant, and the number of days
during the real estate tax fiscal year after delivery of the Floors to Tenant.
For example, assuming the tax fiscal year is the calendar year and the tax is
One Thousand Dollars ($1,000), if the Rent Commencement Date has occurred for
sixty-six percent (66%) of the Agreed Area of the Building on February 1 and the
remaining thirty-four percent (34%) in one-half (1/2)

                                       -23-

<PAGE>

increments on March 1 and April 1, respectively, Tenant's share of Taxes would
be calculated as follows:

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------------------
    (Percentage)        x (Percentage of Year)            x (TOTAL TAX)            = (Tenant's Share of
                                                                                          Taxes)
-----------------------------------------------------------------------------------------------------------
<S>                     <C>                           <C>                          <C>
        (0%)                31/365 = 8.50%                   $1,000                          0
-----------------------------------------------------------------------------------------------------------
       (66%)                28/365 = 7.7%                    $1,000                       $ 50.82
-----------------------------------------------------------------------------------------------------------
       (83%)                30/365 = 8.20%                   $1,000                       $ 68.06
-----------------------------------------------------------------------------------------------------------
       (100%)              276/365 = 75.6%                   $1,000                       $756.00
-----------------------------------------------------------------------------------------------------------
                                                      Aggregate Tenant Share              $874.88
-----------------------------------------------------------------------------------------------------------
</TABLE>

Taxes assessed for a real estate tax fiscal year which extends beyond the Term
shall be apportioned between Landlord and Tenant at the expiration of the Term.
Landlord shall promptly forward to Tenant copies of all notices, bills or other
statements received by Landlord concerning Taxes. Tenant shall pay all such
Taxes to Landlord at least five (5) Business Days before the same become due and
payable or, if later, five (5) days after the bill for same is delivered by
Landlord to Tenant. Tenant's obligation to pay Taxes shall survive the
expiration of the Term or the earlier termination of this Lease. Tenant shall be
obligated to escrow amounts for Taxes on a monthly basis in an amount equal to
one-twelfth (1/12) of the Tenant's Tax Payment if required by any Mortgagee
holding a first-priority mortgage lien on the Premises, provided, that (i) such
escrowed amounts shall be deposited in an interest-bearing account and (ii) such
Mortgagee shall be obligated to apply such escrowed amounts to the payment of
Taxes when due notwithstanding any default of Landlord thereunder, and shall so
confirm, in writing, to Tenant. Any such estimate shall be based on a reasonable
estimate of Taxes for such year (which shall be based on the prior year's tax
bill, any phase-in information, and any subsequent re-assessment information)
and the parties shall reconcile tax payments within 120 days after the end of
the tax year (i.e., pursuant to Section 8.5 below).

     Section 8.3  Tax Proceedings. Except during the last two (2) Lease Years of
                  ---------------
the Term, but only so long as Tenant is either the sole tenant of the Building
or is leasing at least seventy-five percent (75%) of the Agreed Area thereof,
Tenant shall have the right to direct Landlord to institute and diligently
pursue proceedings to contest Taxes or to reduce the Assessed Valuation of the
Premises. Such proceedings shall not be settled without Tenant's consent, not to
be unreasonably withheld, conditioned or delayed, and Tenant shall otherwise
have the right to participate in such tax contest, at Tenant's sole expense.
Thereafter, only Landlord shall determine if and when to institute such
proceedings; provided, however, that notwithstanding the foregoing, in the event
that (i) the Assessed Valuation during any tax fiscal year exceeds one hundred

                                       -24-

<PAGE>

five percent (105%) of the Assessed Valuation during the immediately preceding
tax fiscal year, and (ii) Landlord has not contested Taxes or challenged the
Assessed Valuation during such tax fiscal year or the immediately preceding tax
fiscal year, Landlord agrees to institute proceedings to contest Taxes or reduce
the Assessed Valuation upon Tenant's request. To the extent that the costs
incurred by Landlord in connection with proceedings instituted pursuant to the
immediately preceding sentence are not recovered by Landlord as part of Tenant's
Tax Payment or Operating Expense Payment, Tenant shall reimburse Landlord for
such costs within thirty (30) days after demand. If Landlord receives a refund
of Taxes to the extent that such refund is based upon a payment made by Tenant,
Landlord shall, at its election, either pay to Tenant, or (unless the Lease has
terminated) credit against subsequent payments of Rent due hereunder, an amount
equal to Tenant's Proportionate Share of the refund, net of any actual,
out-of-pocket expenses incurred by Landlord in achieving such refund and not
recovered, which amount shall not exceed Tenant's Tax Payment paid for such tax
fiscal year. Except as expressly set forth above in this Section 8.3, Landlord
shall not be obligated to file any application or institute any proceeding
seeking a reduction in Taxes or the Assessed Valuation. Landlord will engage
annually in a good faith review of Taxes and any reassessments of the Premises
for purposes of determining whether to contest or appeal any such assessment or
impositions.

          Section 8.4  Tenant's Operating Expense Payment.
                       ----------------------------------

                       (a) Tenant shall pay as Additional Rent, Tenant's
Proportionate Share of Operating Expenses for each calendar year ("Tenant's
Operating Expense Payment"), commencing with the earliest Rent Commencement
Date; provided, that, irrespective of Tenant's Proportionate Share, Tenant shall
pay the entire cost of any additional service provided to Tenant pursuant to
this Lease at Tenant's request. During the Partial Term, Tenant's Operating
Expense Statement shall reflect Tenant's obligation to pay Tenant's
Proportionate Share of the Operating Expenses relating to the portion of the
Building for which Rent Commencement Dates have occurred, and the number of days
during the calendar year after such occurrence. Landlord shall make a reasonable
estimate of Tenant's Proportionate Share of the Operating Expenses for each
calendar year, and, so long as Tenant leases at least seventy-five percent (75%)
of the Agreed Area of the Building, shall submit to Tenant for Tenant's
approval, not later than thirty (30) days prior to the earliest Rent
Commencement Date, and no later than December 1 of each subsequent calendar
year, a reasonably itemized budget (the "Operating Budget") setting forth the
monthly projected staffing and Operating Expenses and Taxes for the following
calendar year (including a list of proposed on-site management personnel and
budgets for the Parking Garage and the Building's allocable share of expenses
relating to the Association), or, with respect to the Operating Budget to be
submitted thirty (30) days before the earliest Rent Commencement Date, for the
initial calendar year (or portion thereof) during the term (the "Initial
Calendar Year"). So long as Tenant leases at least seventy-five percent (75%) of
the Agreed Area of the Building, Tenant shall have the right to direct Landlord
to vote, as owner of the Premises, as Tenant deems appropriate, in Tenant's sole
and absolute discretion, as to all matters relating to discretionary costs
imposed under the Association Declaration or otherwise charged by the
Association. Each Operating

                                      -25-

<PAGE>

Budget shall include allocations for maintenance, safety, management and other
Building Services at the level found in Comparable Buildings. Tenant shall pay
along with each month's installment of Fixed Rent one-twelfth (1/12) of the
approved Operating Budget, except that with respect to the Operating Budget to
be submitted for the Initial Calendar Year, Tenant's Proportionate Share of
Operating Expenses shall be payable in equal monthly installments over such
period.

               If Landlord's estimate of Operating Expenses for any calendar
year is not received by December 1 of the preceding calendar year or is not
thereafter approved by Tenant within thirty (30) days, Tenant shall continue to
pay the monthly installments of Tenant's Proportionate Share of Operating
Expenses at the rate and Landlord shall provide service at the level established
for the preceding calendar year increased to reflect any actual increases
projected in Operating Expenses (other than Controllable Expenses), until Tenant
receives and approves a new Operating Budget for the calendar year.

               Tenant shall have no such approval rights if Tenant is leasing
less than 75% of the Agreed Area of the Building. In addition, Tenant shall only
have the right to approve line items on any Operating Budget that are
Discretionary Expenses. In all other cases involving approval of repair and
maintenance items, Tenant agrees to take into consideration Landlord's
obligation to maintain a first class building and to protect the value of its
asset. Upon approval of the new Operating Budget, Tenant's monthly share of
Operating Expenses shall be calculated to reflect payments made pursuant to the
preceding calendar year's Operating Budget. Within forty-five (45) days after
the end of each calendar quarter, Landlord agrees to provide Tenant with a
quarterly report setting forth disbursements to vendors and indicating what
percentage of the Operating Budget has been expended as of the date set forth in
the report. To the extent Landlord determines that costs incurred with respect
to Discretionary Expenses reflected within the Approved Budget will vary by more
than five percent (5%) from the budgeted amount on an annual basis, Landlord
will endeavor to notify Tenant promptly thereafter to alert Tenant of such
likely budgetary variance and to consult with Tenant regarding potential means
of achieving cost savings, or modifications to service in order to minimize
Operating Expenses for the applicable period. Landlord further agrees not to
enter into any contracts related to the operation and management of the Building
which are not terminable on thirty (30) days notice for cause or on ninety (90)
days notice without cause without Tenant's prior consent, except relating to
elevators, fire alarms and life safety equipment.

               (b)  Annual Operating Expense Statement. Within one hundred and
                    ----------------------------------
twenty (120) days after the Initial Calendar Year and thereafter, within one
hundred and twenty (120) days after the end of each calendar year, Landlord
shall submit to Tenant a statement prepared by Landlord (the "Expense
Statement") setting forth in reasonable detail the Operating Expenses (and
Taxes) for such calendar year and the amount of Tenant's Proportionate Share of
the Operating Expenses (and Taxes) for such calendar year. If Tenant's
Proportionate Share of the Operating Expenses so stated is more than the amount
(if any) theretofore paid by Tenant for Operating Expenses for the period
covered by the Expense Statement, Tenant shall pay to

                                      -26-

<PAGE>

Landlord the deficiency within thirty (30) days after the submission of the
Expense Statement. If Tenant's Proportionate Share of the Operating Expenses
(and Taxes) so stated is less than the amount (if any) theretofore paid by
Tenant for Operating Expenses for the period covered by the Expense Statement,
Landlord shall credit the excess against the next monthly installment of Rent
thereafter payable by Tenant under this Lease, except that Landlord shall refund
the excess (if any) for the calendar year ending with or within the last Lease
Year to Tenant within thirty (30) days after submission of the Expense Statement
for such calendar year. If the last day of the Term shall not coincide with the
end of a calendar year, Tenant shall pay Tenant's Proportionate Share of the
Operating Expenses for the calendar year in which the last day of the Term
occurs up to and including the last day of the Term as if the last day of the
Term were the end of a calendar year. Tenant's obligation under this subsection
to pay Tenant's Proportionate Share of the Operating Expenses and Landlord's
obligation to reimburse Tenant for an overpayment of Tenant's Proportionate
Share of the Operating Expenses shall survive the expiration of the Term or the
earlier termination of this Lease.

          Section 8.5  Disputes. Landlord's books and records with respect to
                       --------
Operating Expenses and Taxes shall be kept on an accrual basis in accordance
with GAAP consistently applied. Each Expense Statement, in a form sufficiently
detailed and complete for Tenant's adequate review, sent to Tenant shall be
conclusively binding upon Tenant unless Tenant shall, within one (1) year after
such Expense Statement is received, give notice to Landlord objecting to such
Expense Statement and specifying the reasons that such Expense Statement is
claimed to be incorrect (to the extent then known by Tenant). Notwithstanding
the foregoing, Tenant shall, within thirty (30) days after such Expense
Statement is received, pay to Landlord the amount set forth in such Expense
Statement, without prejudice to Tenant's right to dispute such Expense
Statement. No such objection shall prejudice Tenant's right to make further
objections with respect to the same Expense Statement within the permitted time
period. Tenant shall have the right at its sole cost and expense to review or
audit Landlord's books and records relating to Landlord's calculation of
Operating Expenses and Taxes (for such year) at any time within one (1) year
from Tenant's receipt of the Expense Statement, and may use the auditor or
reviewer of its choice, provided, however, that Tenant may not hire an auditor
or reviewer paid on a contingency fee basis unless such auditor's area of
expertise includes lease expense analysis and such auditor is recognized for
such expertise. Tenant shall be obligated to reimburse Landlord for its
reasonable costs of responding to any claim by Tenant that it is entitled to a
refund, in the proportion that (A) the amount which Tenant initially claimed
less the amount actually recovered bears to (B) the amount of the initial
claimed adjustment in Operating Expenses or Taxes. Landlord shall have the right
to reasonably revise its calculation of Operating Expenses at any time within
one (1) year from the date of the Expense Statement which shall be binding on
Landlord thereafter, and any such revision shall be deemed a new Expense
Statement for purposes hereof. Tenant shall not be required to notify Landlord
of the results of Tenant's audit. If the parties are unable to resolve a dispute
as to the correctness of an Expense Statement within thirty (30) days following
Tenant's notice of objection, either party may refer the issues raised to an
accountant

                                      -27-

<PAGE>

reasonably acceptable to the other party, and that has not and does not provide
accounting and consulting services to Landlord or Tenant or any of their
respective Affiliates and does not otherwise have any affiliation or business
relationship with Landlord or Tenant or any of their respective Affiliates, and
the decision of such accountants shall be conclusively binding upon Landlord and
Tenant. In the event that Landlord and Tenant are unable to agree, such
accountant shall be selected by the AAA in the manner provided in Section 34.2
hereof. In connection with any review or audit of Operating Expenses, Landlord,
Tenant and its reviewer or auditor shall execute and deliver to Landlord a
confidentiality agreement, in form and substance reasonably satisfactory to all,
whereby such parties agree not to disclose to any third party any of the
information obtained in connection with such review, except as reasonably
necessary to attorneys, arbitrators or other similar professionals in connection
with such audit or in the event of any dispute or litigation between the
parties. The fees and expenses relating to the accountant hired to conclusively
resolve the dispute as to the correctness of the Expense Statement and, if the
expenses were overstated by more than three and one half percent (3.5%), the
fees and expenses of Tenant's auditor or reviewer, shall be borne by the
unsuccessful party (and if both parties are partially unsuccessful, the
accountant shall apportion the fees and expenses between the parties based on
the degree of success of each party). In the event there is an adjustment of the
Expense Statement, the amount owed by either party shall be increased by
interest on the sum owed calculated at the Base Rate from the date of the
original payment until the date the adjustment is paid.

                                    ARTICLE 9
                               REQUIREMENTS OF LAW
                               -------------------

          Section 9.1  Tenant's Compliance. Tenant, at its expense, shall comply
                       -------------------
(or cause to be complied) with all Requirements applicable to (x) the Initial
Installations and (y) otherwise applicable to the Premises and first enacted or
imposed after the initial Rent Commencement Date, regardless of whether imposed
by their terms upon Landlord or Tenant, and which do not require any structural
changes to the Premises. Notwithstanding the foregoing, all repairs and
alterations to the Premises, whether structural or nonstructural, ordinary or
extraordinary, required to be made to cause the Premises to comply with any
Requirements and which arise as a result of (i) the specific manner and nature
of Tenant's use or occupancy of the Premises, as distinct from general office
use, (ii) Alterations made by Tenant in the Premises or (iii) a breach by Tenant
of any provisions of this Lease, shall be made by Tenant, at Tenant's expense
and in compliance with Article 5, if such repairs or alterations are
                       ---------
nonstructural and do not affect any Building System, or by Landlord, at Tenant's
reasonable expense, if such repairs or alterations are structural or affect any
Building System. If Tenant obtains knowledge of any failure to comply with any
Requirements applicable to the Premises, Tenant shall give Landlord prompt
written notice thereof.

          Section 9.2  Landlord's Compliance. Landlord shall comply with (or
                       ---------------------
cause to be complied with) all Requirements applicable to the Premises which are
related to the structural components thereof and do not arise out of the matters
described in clauses

                                      -28-

<PAGE>

(i), (ii) or (iii) of Section 9.1; and the cost thereof shall be included in
Operating Expenses pursuant to Section 8.1(b) of this Lease if the Requirement
shall not apply to the Premises as of the Commencement Date. Landlord shall, as
part of the Base Building Work (but not as an Operating Expense), cause the Base
Building to comply as of the Commencement Date with all applicable Requirements
(including the ADA), and with all requirements of all insurance bodies affecting
the Premises which are customarily applicable to Comparable Buildings. From and
after the Commencement Date, Landlord shall be responsible, for compliance with
Requirements as they relate to the Common Areas and the Building generally and
the costs thereof shall, in accordance with the terms of Section 8.1, be charged
as Operating Expenses.

          Section 9.3  Hazardous Materials.
                       -------------------

                       (a)  From and after the Commencement Date, Tenant shall
not (i) cause or permit the storage or use of Hazardous Materials in any manner
not permitted by any Requirements, or (ii) cause or permit the escape, disposal
or release of any Hazardous Materials within or from the Premises, except to the
extent that any of the foregoing actions are caused by Landlord or any party
claiming by, through or under Landlord. Nothing herein shall be deemed to
prevent the use of any Hazardous Materials customarily used in the construction
or normal operation of office buildings in Comparable Buildings, provided such
use is in accordance with all Requirements. Tenant shall be responsible, at its
expense, for all matters directly or indirectly based on, or arising or
resulting from, the actual or alleged presence of Hazardous Materials in the
Premises, which is caused or permitted by Tenant. Tenant shall provide to
Landlord copies of all communications received by Tenant with respect to any
Requirements relating to Hazardous Materials, and/or any claims made in
connection therewith and applicable to the Premises or Landlord. Upon reasonable
prior written notice to Tenant (except in the event of an emergency), so long as
Landlord does not unreasonably interfere with Tenant's business operations,
Landlord or its agents may perform environmental inspections (at its cost) of
the Premises subject to the limitations set forth herein.

                       (b)  Landlord hereby represents and warrants that, except
as set forth in that certain Phase I Environmental Site Assessment--CFC Tract
dated July 7, 1997, prepared by Environmental Consulting Services, Ltd. it has
received no notice, and has no actual knowledge, of any Hazardous Materials on,
in or under the Premises, including in connection with the initial construction
of the Building. For purposes of this Lease, the knowledge of Landlord shall be
limited to the actual knowledge of James A. Evans, Rustom Cowasjee, Simon
Wasserberger, Steven F. Grant and Andrew J. Nathan. There shall be no personal
liability to said individuals arising out of said representations or warranties
(all liability therefrom being attributable to Landlord hereunder).

                       (c)  From and after the Effective Date, Landlord  shall
not cause or permit the escape, disposal or release of any Hazardous Materials
within or from the Premises, except to the extent that any of the foregoing
actions are caused by Tenant or any party claiming by, through or under Tenant.
Landlord shall be responsible, at its

                                      -29-

<PAGE>

expense, for all matters directly or indirectly based on, or arising or
resulting from, the actual or alleged presence of Hazardous Materials in the
Premises, which is caused by Landlord or permitted by Landlord. Landlord shall
provide to Tenant copies of all communications received by Landlord with respect
to any Requirements relating to Hazardous Materials, and/or any claims made in
connection therewith, and applicable to the Premises or Tenant.

                    (d)  Nothing herein shall be deemed to prevent the use of
any Hazardous Materials customarily used (i) in the ordinary course of Tenant's
business operations in accordance with the Permitted Uses, or (ii) in the
ordinary course of Landlord's business operations provided that, in either (i)
or (ii), such use is in accordance with all Requirements.

                    (e)  The covenants contained in this Section 9.3 shall
survive the expiration or earlier termination of this Lease.

          Section 9.4  Landlord's Insurance. Tenant shall not cause or knowingly
                       --------------------
permit any action or condition that would (i) invalidate or conflict with
Landlord's insurance policies, provided such policies contain terms which are
customarily applicable to Comparable Buildings, (ii) violate applicable
Requirements, (iii) cause an increase in the premiums of fire insurance then
covering the Building over that payable with respect to Comparable Buildings or
(iv) result in insurance companies of good standing refusing to insure the
Building or the Land in amounts and against risks as reasonably determined by
Landlord and which are customarily applicable to Comparable Buildings. If the
fire insurance premiums increase as a result of Tenant's failure to comply with
the provisions of this Article 9, Tenant shall promptly cure such failure and
                       ---------
shall reimburse Landlord, as Additional Rent, for the increased fire insurance
premiums paid by Landlord as a result of such failure by Tenant. In any action
or proceeding to which Landlord and Tenant are parties, a schedule or "make up"
of rates for the Building issued by the appropriate Fire Insurance Rating
Organization, or other body fixing such fire insurance rates, shall be
presumptive evidence of the fire insurance rates then applicable to the
Building. Landlord represents that, to Landlord's knowledge as of the date
hereof, use of the Building for the Permitted Uses will not increase the rate of
fire or other insurance on the Building.

                                   ARTICLE 10
                                  SUBORDINATION
                                  -------------

          Section 10.1 Subordination and Attornment. Subject to Section 10.5
                       ----------------------------
hereof, this Lease is subject and subordinate to all Mortgages and Superior
Leases and, at the request of any Mortgagee or Lessor, Tenant shall attorn to
such Mortgagee or Lessor, its successors in interest or any purchaser in a
foreclosure sale pursuant to the foreclosure of such mortgage.

          Section 10.2 Mortgage Priority; Modification. Any Mortgagee or Lessor
                       -------------------------------
may elect that this Lease shall have priority over the Mortgage or Superior
Lease that it holds and, upon notification to Tenant by such Mortgagee or
Lessor, this Lease shall be

                                      -30-

<PAGE>

deemed to have priority over such Mortgage or Superior Lease, regardless of the
date of this Lease. In connection with any financing of the Building, Tenant
shall consent to any reasonable modifications of this Lease requested by any
lending institution, provided such modifications do not increase the
obligations, or adversely affect the rights, of Tenant under this Lease.

          Section 10.3  Tenant's Termination Right. As long as any Mortgage or
                        --------------------------
Superior Lease shall exist and Tenant has been provided notice of same, Tenant
shall not seek to exercise any termination or other right it may have under this
Lease, at law, in equity or otherwise, if any, by reason of any act or omission
of Landlord (a) until Tenant shall have given notice of such act or omission to
all such Mortgagees or Lessors, and (b) until thirty (30) days shall have
elapsed following the giving of notice of such default and the expiration of any
applicable notice or grace periods applicable to Landlord under this Lease
(unless such act or omission is not capable of being remedied within such
period, such Mortgagee or Lessor has, within such thirty (30) day period,
notified Tenant that it intends to remedy such circumstance and has thereafter
commenced and is diligently pursuing with continuity a remedy but in no event
more than one hundred fifty (150) days after the expiration of the aforesaid
thirty (30) day period), during which period such Mortgagees or Lessors shall
have the right, but not the obligation, to remedy such act or omission and
thereafter diligently proceed to so remedy such act or obligation. If any
Mortgagee or Lessor so elects to remedy such act or omission of Landlord, Tenant
shall not to exercise any termination or other right it may have under this
Lease, at law, in equity or otherwise, if any, by reason of any act or omission
of Landlord so long as such Mortgagee or Lessor is proceeding with reasonable
diligence to effect such remedy. The provisions of this Section 10.3 are not
intended in any way to affect any of Tenant's self-help rights under this Lease.

          Section 10.4  Provisions. The provisions of this Article 10 shall (a)
                        ----------                         ----------
inure to the benefit of Landlord, Tenant, Mortgagee, or Lessor and their
respective successors and assigns, and (b) apply notwithstanding that, as a
matter of law, this Lease may terminate upon the termination of any such
Mortgage or Superior Lease.

          Section 10.5  Non-Disturbance Agreements. Notwithstanding anything in
                        --------------------------
this Lease to the contrary, as a condition precedent to Tenant's agreement
hereunder to subordinate Tenant's interest in the Lease and attorn to any
Mortgage or Superior Lease made between Landlord and such Mortgagee or Lessor,
whether now or hereafter existing, Landlord shall obtain from each Mortgagee or
Lessor, whether now or hereafter existing, cause to be recorded, and deliver to
Tenant an agreement, substantially in the form attached hereto as Exhibit E or
                                                                  ---------
otherwise meeting the definition of a Non-Disturbance Agreement hereunder. If
Lender does not require the recording of the Non-Disturbance Agreement, and
Tenant elects to record such Non-Disturbance Agreement, Tenant shall bear the
cost of such recordation. "Non-Disturbance Agreement" shall mean a
subordination, non-disturbance and attornment agreement from each Mortgagee or
Lessor in a form to be negotiated between (and reasonably satisfactory to)
Landlord, Tenant and the applicable Mortgagee or Lessor (sometimes referred to
herein as "Lender"), which is executed by Landlord, Tenant and

                                      -31-

<PAGE>

the Lender, which is duly recorded in the land records of Fairfax, County,
Virginia, and which includes the following provisions:

                    (a)  that, provided no uncured Material Default shall then
exist under this Lease, the Mortgagee, any successful foreclosure bidder's
assignee or designee, and any other third party purchaser entity or any holder
of the reversionary interest under a Superior Lease succeeding to Landlord's
and/or Lender's or their respective successors' and assigns' interest
(collectively, "Senior Lienors") shall not: (i) disturb Tenant's rights,
privileges, interests and unexercised options under this Lease or any instrument
executed pursuant hereto, nor name Tenant as a party defendant in any
foreclosure or any action or proceeding instituted under or in connection with
the Mortgage or Superior Lease unless such joinder is necessary to foreclose the
Mortgage or terminate the Superior Lease, and then only for such purpose and not
for the purpose of terminating this Lease or reducing any rights under the Lease
because of any default under the Mortgage; (ii) terminate this Lease if there is
a foreclosure, deed-in-lieu, or other proceedings involving Landlord's interest
in the Building; and/or (iii) require any Lease modification in connection
therewith (except as provided in Section 10.2);

                    (b)  that notwithstanding anything contained herein to the
contrary, Senior Lienor shall not be bound by any obligation to perform any work
or to make improvements to the Building except for (x) repairs and maintenance
required to be made by Landlord under this Lease, subject to subsection (d)(i)
below, and (y) repairs to the Building as a result of damage by fire or other
casualty or a partial condemnation pursuant to the provisions of this Lease, but
only to the extent that such repairs can reasonably be made from the net
proceeds of any insurance or condemnation awards, respectively, actually made
available to such successor landlord; provided, that if such Senior Lienor
elects not to repair such damage by fire, casualty or condemnation, Tenant shall
have the right to terminate this Lease pursuant to Article 13 hereof;
                                                   ----------

                    (c)  Tenant shall be required to attorn to such Senior
Lienor as long as such Senior Lienor recognizes Tenant and assumes (either
expressly or by operation of law) the obligations of "Landlord" under this Lease
for the period after the date title to the Property is transferred to such
Senior Lienor by Landlord (the "Foreclosure Date");

                    (d)  no Senior Lienor shall be:

                         (i)   liable for any act or omission of Landlord with
respect to which Senior Lienor has not received prior written notice, except for
acts, omissions or defaults of a continuing nature requiring cure under this
Lease, which continue after the Foreclosure Date and which are not thereafter
cured by Senior Lienor after notice and an opportunity to cure as provided
herein (including, without limitation, any failure by Landlord to fund any
allowances or Tenant's inability to fully recognize any offsets or credits under
this Lease);

                                      -32-

<PAGE>

                          (ii)   subject to any offsets (other than the Special
Offset Amounts, as defined in Section 19.2(b)) or defenses which Tenant may have
had against any prior landlord, except (A) the foregoing shall not operate to
cut off defenses or offsets Tenant may have in relation to any breach, act or
omission of the landlord which continues after the Foreclosure Date (but such
defenses and/or offsets shall apply only to the extent such breach, act or
omission continues after such Senior Lienor assumes title); Senior Lienor shall
not be relieved of the obligation to comply with all of the landlord's
obligations under the Lease accruing from and after the Foreclosure Date,
irrespective of whether the original non-compliance with any such obligation
arose prior to and is continuing as of the Foreclosure Date, or arose on or
after the Foreclosure Date (provided however that if such obligation arose prior
to the Foreclosure Date, such Senior Lienor shall not be deemed in default until
after the provision of any notice of default required by this Lease to such
Senior Lienor, and its failure to cure same within the cure period provided for
herein), and (B) as set forth in clause (b), above and subclause (vi) below;

                          (iii)  bound by any payment of Rent or Additional Rent
by Tenant for a period greater than one (1) month in advance made without Senior
Lienor's prior written consent (unless actually received by, or otherwise in the
control of, such Senior Lienor);

                          (iv)   bound by any amendment or modification of the
Lease which reduces rent or charges payable under this Lease or shortens or
lengthens the term thereof or otherwise materially affects the rights of
Landlord (in more than a de minimis manner) and made after the Mortgage or
Superior Lease was recorded (or earlier, if Tenant was notified earlier) without
Senior Lienor's prior written consent, if and to the extent required by the
Senior Lienor's loan documents;

                          (v)    liable for the Security Deposit given by Tenant
to a prior landlord (including Landlord) unless such Security Deposit is
actually delivered to Senior Lienor by the prior landlord or otherwise in the
control of Senior Lienor; or

                          (vi)   bound by any obligation to make any payment to
Tenant which was required to be made prior to the time such successor landlord
succeeded to Landlord's interest, other than the Special Offset Amounts
(including any unpaid portion of Landlord's Contribution). In addition, Tenant
shall not be required to name Landlord or Senior Lienor as Tenant's
attorney-in-fact for any reason, nor pay any attorneys fees or servicing charges
or expenses related to the Non-Disturbance Agreement or any estoppel
certificate. Landlord and Tenant agree that, notwithstanding any of the
foregoing provisions to the contrary, Exhibit E shall constitute a commercially
                                      ---------
reasonable form of Non-Disturbance Agreement that is acceptable to each of them
and that may be used and/or delivered in connection with any Mortgage or
Superior Lease, so long as such Non-Disturbance Agreement is recorded in the
applicable land records.

                    (e)   that, if Senior Lienor shall become the owner of the
Property, or the Property shall be sold by reason of non-judicial or judicial
foreclosure or

                                      -33-

<PAGE>

other proceedings brought to enforce the Mortgage, or the Property shall be
conveyed by deed in lieu of foreclosure, Tenant agrees to pay all Rent directly
to Senior Lienor in accordance with this Lease promptly upon receipt of written
notice from Senior Lienor. Tenant further agrees to pay all Rent directly to
Senior Lienor immediately upon notice that Senior Lienor is exercising its
rights to such Rent under the Mortgage or any other loan documents (including
but not limited to any Assignment of Leases and Rents) following a default by
Landlord or other applicable party and Landlord acknowledges the same.
Notwithstanding the foregoing, Tenant shall be under no obligation to ascertain
whether a default by Landlord has occurred under the Mortgage or any other loan
documents or whether such demand by Senior Lienor is permitted under the loan
documents, and Landlord waives any right, claim or demand it may now or
hereafter have against Tenant by reason of such direct payment to Lender and
agrees that such direct payment to Lender shall discharge all obligations of
Tenant to make such payment to Landlord and if Tenant makes such payment,
Landlord shall indemnify, defend, protect and hold Tenant harmless from and
against any and all Losses which Tenant may incur by reason of same.

                                   ARTICLE 11
                             SERVICES AND UTILITIES
                             ----------------------

     Section 11.1 Building Services.
                  -----------------

                  (a)   Prior to the Commencement Date, Landlord at Landlord's
sole cost and expense shall maintain the interior temperature of the Building
above thirty-two degrees Fahrenheit (32(0)F), perform preventative maintenance
to the Building Systems, and service the Building with a part-time engineer
reasonably sufficient to protect the Building and the Building Systems.

                  (b)   Throughout the Term, Landlord shall maintain the
Premises in a first-class manner consistent with Comparable Buildings, shall
operate all Building Systems consistent with the Plans and Specifications, and,
subject to Unavoidable Delays, all Requirements, the provisions of this Article
                                                                        -------
11 and the approved Operating Budget, and shall furnish, or cause to be
--
furnished, the following services ("Building Services"):

                        (i)   Subject to the provisions of Section 11.2, normal
and usual electricity for interior and exterior lighting purposes for the
Building, the Parking Garage, surface parking areas and Common Areas, and the
operation of ordinary office equipment and HVAC service and lighting in
accordance with the design capabilities of the Building and such other services
to the Building (all in accordance with the Base Building Construction
Documents), the Parking Garage, surface parking areas and Common Areas as may be
required under this Lease;

                        (ii)  Public lavatory facilities and adequate supplies
for toilet rooms throughout the Premises;

                                      -34-

<PAGE>

                        (iii)  In accordance with the specifications contained
within the Base Building Construction Documents, hot and cold running water in
toilet rooms, kitchens and pantries throughout the Premises as well as
sufficient running water for HVAC and other applicable uses;

                        (iv)   Heating, ventilating and air-conditioning to the
Building (zoned Floor-by-Floor) during Business Hours, in accordance with the
specifications attached as Exhibit L;
                           ---------

                        (v)    Automatically operated elevator service (with at
least eight (8) passenger elevators and one freight elevator) twenty-four (24)
hours a day, seven days a week;

                        (vi)   Building Standard lighting fixtures, electric
bulbs and fluorescent tubes in light fixtures in the Premises (including the
Parking Garage and the Land);

                        (vii)  A controlled access security system for the
Premises (including the Parking Garage) permitting access thereto twenty-four
(24) hours a day, three hundred sixty-five (365) days a year, via a Kastle or
similar key-card system, including key-cards for such system and Building
concierge/security personnel during Business Hours;

                        (viii) Landscaping maintenance, road and driveway
repair, and snow removal;

                        (ix)   Janitorial and char services to the Premises
(including the cafeteria, kitchen and dining area, however, if the Building is
occupied by more than one (1) tenant, such services shall be considered a
"tenant extra" to be paid for directly by Tenant and Operating Expenses will be
appropriately reduced on account thereof), including trash removal and
recycling, Monday through Friday, excepting holidays, in accordance with the
cleaning specifications attached hereto as Exhibit F;
                                           ---------

                        (xi)   Operational fire alarm and life safety systems
(which, to the extent applicable, shall include telecommunications systems which
are a part of such systems) in accordance with applicable Requirements; and

                        (x)    Utility and other service to the Parking Garage
for purposes of lighting, ventilation (if any).

                  (c)   Landlord agrees to seek at least three competitive bids
from a list of qualified service providers reasonably acceptable to Tenant for
any service or work provided to the Premises, other than service or work related
to fire alarms and other life safety equipment, Building management or any other
services not included in Operating Expenses. Landlord shall select in its
reasonable discretion the lowest responsive bid from among the qualified
bidders. All costs of providing Building Services shall be included as an
Operating Expense, unless specifically excluded in Article 8 or separately
                                                   ---------
charged to Tenant. Provided Tenant gives Landlord notice at

                                      -35-

<PAGE>

least thirty (30) days in advance, Tenant shall have the right at its sole
option to temporarily or permanently increase, reduce the scope of janitorial
services, security services, or other Building Services relating to
Discretionary Expenses to be provided and/or performed by Landlord for Tenant's
benefit pursuant to this Lease, for such period as Tenant may desire, and with
Tenant to pay the additional cost, or receive any economic benefit, that results
therefrom (in the form of an increase or reduction in Operating Expenses, as the
case may be). Any such service which Tenant may elect to reduce, curtail or
eliminate during the Term hereof is hereinafter referred to as a "Reduced
Service". Notwithstanding the foregoing: (i)Tenant shall not have the right to
require Landlord to temporarily or permanently reduce, curtail or eliminate any
services deemed by Landlord in its good faith judgment to be necessary or
appropriate for the proper operation, maintenance and repair of the Premises in
a condition comparable to Comparable Properties, and (ii) the cleaning and
janitorial services provided by such third party provider comply with the
standards set forth in Exhibit F.
                       ---------

                  (d)  Landlord agrees, on an ongoing basis throughout the Term,
to consult with Tenant, and to afford Tenant the opportunity to provide
meaningful input regarding the scope of services and amenities supplied to the
Building and Waterview, including providing Tenant, as appropriate, with status
reports regarding such services and amenities, and considering in good faith,
and accommodating where reasonably possible, Tenant's reasonable suggestions,
subject to applicable provisions of the Association Declaration.

     Section 11.2 Utilities. For so long as Tenant leases one hundred percent
                  ---------
(100%) of the Agreed Area of the Building, all utilities serving the Premises
shall be separately metered to, and paid by, Tenant. Subject to Section 7.4,
Landlord shall not be liable in any way to Tenant for any failure or defect in
the supply or character of utilities furnished to the Building by reason of any
requirement, act or omission of any public utility providing the Premises with
utilities unless resulting from Landlord's failure to make payment for same.
Tenant's use of electrical energy in the Building shall not at any time exceed
the capacity of any of the electrical conductors and equipment in or otherwise
serving the Building, as set forth on Exhibit L. Tenant shall not install or
                                      ---------
operate in the Building any electrically operated equipment which uses electric
current in excess of such capacity without Landlord's prior consent, which
consent may be conditioned upon Tenant's agreement to pay an additional charge
to pay the actual, arms-length cost of any additional wiring or electrical
equipment or installations which may be required for the operation of such
equipment. Any feeders or risers to supply Tenant's electrical requirements in
addition to those originally installed in accordance with the Plans and
Specifications, and all other equipment proper and necessary in connection with
such feeders or risers, shall be installed by Landlord upon Tenant's request, at
the cost and expense of Tenant, but only if, in Landlord's reasonable judgment,
such additional feeders or risers are permissible under all Requirements and the
installation of such feeders or risers will not materially adversely affect the
Building or cause or create a dangerous condition.

     Section 11.3 Payment of Cost of Utilities. Commencing on the Last Rent
                  ----------------------------
Commencement Date and continuing thereafter throughout the Term, the cost of all

                                      -36-

<PAGE>

utilities for the Premises, including electricity used for lighting the exterior
of the Building and surface walkways and parking areas and landscaped areas on
the Land adjacent to the Building, shall be included in Operating Expenses.
During the Partial Term it is agreed that Landlord shall be responsible for
utility costs, except that Tenant shall be responsible for the utility costs
relating to the Floors then occupied by Tenant. Landlord shall obtain billings
and meter readings for utilities as of the Business Day closest to, but
preceding, each Rent Commencement Date to aid in the proration of the cost of
utilities. If billings or meter readings as of the Business Day preceding the
Last Rent Commencement Date are not obtained for a utility, the charges for such
utility shall be prorated as of the Last Rent Commencement Date on a per diem
basis in accordance with the first (1st) bills for such utility rendered after
the Last Rent Commencement Date. The cost of utilities shall be prorated at the
expiration of the Term in the same manner as set forth above and Tenant's
obligation to reimburse Landlord for the per diem charges for utilities for the
period up to and including the last day of the Term shall survive the expiration
of the Term or earlier termination of this Lease.

     Section 11.4 Payment of Association Costs. The fees and other costs with
                  ----------------------------
respect to services provided to or for the benefit of the Premises by the
Association shall be paid to the Association by Landlord and included in
Operating Expenses. If during the Partial Term Landlord is billed for such fees
and costs, Landlord shall equitably determine Tenant's share of such fees and
costs based upon the number of Floors for which a Rent Commencement Date has
occurred, and such pro-rated amount shall be included in Operating Expenses. The
fees and other costs with respect to services provided to or for the benefit of
the Premises by the Association shall be prorated at the expiration of the Term
and Tenant's obligation to reimburse Landlord for such fees and costs up to and
including the last day of the Term shall survive the expiration of the Term or
earlier termination of this Lease.

     Section 11.5 Building Management.
                  -------------------

                  (a)   Subject to Section 11.5(c) hereof, Landlord's Agent, or
such other Person as Landlord shall select subject to Tenant's reasonable
approval, which approval shall only be required if Tenant is leasing at least
seventy five percent (75%) of the Agreed Area of the Building, shall provide
building management services customary in Comparable Buildings. Landlord's
Agent's fee shall equal to three percent (3%) per annum of the Fixed Rent plus
Tenant's Proportionate Share of Operating Expenses and Taxes payable under the
Lease. Such fee to Landlord's Agent shall be included in Operating Expenses.

                  (b)   So long as Tenant is leasing at least one hundred
percent (100%) of the Agreed Area of the Building, Landlord's provision of
building management services shall be subject to the following: (1) Tenant shall
have the right to prescribe objective reasonable job-related requirements for
every individual who is an employee of the building management company and who
is providing on-site management services, up to and including the manager of the
Building; (2) Landlord shall enforce such requirements including, at the request
of Tenant, replacing the individual serving as manager of the Building, for
continued non-performance of such person's duties;

                                      -37-

<PAGE>

(3) Landlord shall advise Tenant of all status changes relating to the
management personnel for the Building; and (4) Landlord shall provide Tenant
with the names of two employees of Landlord not directly involved in the
Building's day-to-day management (one in Virginia and one in New York) who will
assist Tenant with any concerns relating to the Building management. Landlord
and/or the management company shall have the sole right to hire, fire, evaluate,
promote and discipline Building management personnel; provided, however, that
Tenant may reasonably request that any such personnel be reassigned to duties
unrelated to the Premises, so long as such action may be taken in a
non-discriminatory manner.

                  (c)   Notwithstanding any provision of this Lease to the
contrary, so long as Tenant leases seventy-five percent (75%) of the Agreed Area
of the Building, in the event that Landlord shall at any time cease to be an
Affiliate of Tishman Speyer Properties, L.P., or vice versa, then Tenant shall
have the right to select the manager of the Premises, subject to the reasonable
approval of Landlord, at reasonable and customary market rates.

                  (d)   Any Building employee to whom any property shall be
entrusted by or on behalf of Tenant shall be deemed to be acting as Tenant's
agent with respect to such property and neither Landlord nor its agents shall be
liable for any damage to such property, or for the loss of or damage to any
property of Tenant by theft or otherwise.

     Section 11.6 Vermin. Landlord shall cause the Premises to be exterminated
                  ------
upon request of Tenant by licensed exterminators. The cost thereof shall be
included in Operating Expenses to the extent permitted by Article 8.

     Section 11.7 Additional Utilities. If Tenant requires Building Services
                  --------------------
other than during Business Hours, Landlord shall provide such additional
Building Service(s) upon reasonable prior notice (which may be oral) therefor.
In the case of after-hours HVAC service, such request shall be effected by use
of an automatic dial-in feature which is part of the Base Building HVAC system.
Tenant shall reimburse Landlord for such additional Building Service(s), as
Additional Rent, at the actual direct cost of such additional Building
Service(s) to Landlord.

     Section 11.8 Shuttle Bus Service. Landlord covenants that not later than
                  -------------------
the first Rent Commencement Date, a shuttle bus service for the non-exclusive
benefit of Tenant shall be provided in accordance with Woodland Park's tenants'
reasonable ridership requirements. The shuttle bus shall at a minimum provide
bus service to the future Route 28/CIT or Herndon/Monroe Metrorail Station, but
the exact bus route and stops shall be established by Landlord taking into
consideration Tenant's reasonable requirements and the needs of other users
within Woodland Park. The actual cost of such service (without mark-up by
Landlord) shall be payable as an Operating Expense among the office tenants of
Woodland Park. The cost will be billed on a pro rata basis, based on the
relative square footage of the tenants' respective premises, or other reasonable
allocation criteria if square footage is not a reasonable and appropriate method
of cost allocation. The use of such shuttle service will be restricted to those

                                      -38-

<PAGE>

tenants and/or occupants of Woodland Park who contribute to the cost thereof,
through the use of identification badges, user cards or other appropriate means.
So long as Tenant leases at least seventy five percent (75%) of the Agreed Area
of the Building, any decision to expand or reduce the usage of the shuttle
service shall be made by Landlord in good faith and only after consultation with
Tenant and with due consideration of Tenant's reasonable ridership requirements.
Notwithstanding the foregoing, Tenant shall have the right to opt-out of the
shuttle bus service set forth in this section (and in such event, the shuttle
bus service shall not be includable as an Operating Expense), upon not less than
thirty (30) days written notice to Landlord.

                                   ARTICLE 12
                                    INSURANCE
                                    ---------

     Section 12.1 Tenant's Insurance.
                  ------------------

                  (a)   Tenant, at its expense, shall obtain (or cause to be
obtained) and keep in full force and effect during the Term on and after the
Commencement Date:

                        (i)   a policy of commercial general liability insurance
on an occurrence basis against claims for bodily injury (including death) and
for property damage occurring in or about the Premises for which Tenant is
legally liable, and including actions of the employees, contractors,
subcontractors, invitees, agents and others working on behalf of Tenant, under
which Tenant is named as the insured and Landlord, Landlord's Agent and any
Mortgagees and Lessors whose names shall have been furnished by Landlord to
Tenant from time to time are named as additional insureds, which insurance shall
provide primary coverage without contribution from any other insurance carried
by or for the benefit of Landlord, Landlord's Agent or any Mortgagees or Lessors
named as additional insureds, and Tenant agrees to obtain blanket broad-form
contractual liability coverage to insure its indemnity obligations set forth in
Article 29 hereof. The minimum limits of liability shall be a combined single
----------
limit with respect to each occurrence in an amount of not less than Twenty-Five
Million Dollars ($25,000,000). The deductible for such policy shall in no event
exceed Ten Thousand Dollars ($10,000) at any time. If the aggregate limit of
such coverage is reduced by the payment of a claim or establishment of a reserve
equal to or greater than fifty percent (50%) of the annual aggregate, Tenant
shall immediately arrange to have the aggregate limit restored by endorsement to
the existing policy or the purchase of an additional insurance policy unless, in
Landlord's reasonable judgment, Tenant maintains sufficient excess liability
insurance with a "drop-down" endorsement to satisfy the liability requirements
of this Lease without the reinstatement of the aggregate limit;

                        (ii)  insurance against loss or damage by fire, and such
other risks and hazards as are insurable under then available standard forms of
"all risk" property insurance policies, insuring Tenant's Property and all
Specialty

                                      -39-

<PAGE>

Alterations for the full replacement cost thereof, having a deductible amount,
if any, as reasonably determined by Tenant, but in no event greater than
$25,000;

                        (iii) during the performance of any Alteration,
including the Initial Installations, until completion thereof, builder's risk
insurance on an "all risk" basis and on a completed value form including a
Permission to Complete and Occupy endorsement, for full replacement value
covering the interest of Landlord and Tenant and any Mortgagee or Lessor of
which Tenant has been given notice in all work incorporated in the Building and
all materials and equipment in or about the Premises;

                        (iv) Workers' Compensation Insurance, as required by
law;

                        (v) Business Interruption Insurance; and

                        (vi) such other insurance in such amounts as Landlord
and/or any Mortgagee or Lessor may reasonably require from time to time and is
then being customarily required of tenants in Comparable Buildings.

                  (b)   All insurance required to be carried by Tenant pursuant
to the terms of this Lease (i) shall contain a provision that (x) only material
statements or acts that would ordinarily void or suspend coverage will adversely
affect the rights of the offending party, (y) the policy shall be noncancellable
and/or no material change in coverage shall be made thereto unless Landlord and
Mortgagees and Lessors which are additional insureds or loss payees thereunder
shall have received thirty (30) days (ten (10) days written notice for
non-payment) prior written notice of the same, and (z) Tenant shall be solely
responsible for the payment of all premiums under such policies and Landlord and
Mortgagees and Lessors shall have no obligation for the payment thereof, and
(ii) shall be effected under valid and enforceable policies issued by reputable
and independent insurers authorized to do business in the Commonwealth of
Virginia and rated in Best's Insurance Guide, or any successor thereto (or if
there be none, an organization having a national reputation) as having a "Best's
Rating" of "A-" and a "Financial Size Category" of at least "X" or, if such
ratings are not then in effect, the equivalent thereof.

                  (c)   On or prior to the initial Rent Commencement Date (or,
if earlier, the date that Tenant takes actual possession of the Premises),
Tenant shall deliver to Landlord appropriate policies of insurance, including
evidence of waivers of subrogation required to be carried by each party pursuant
to this Article 12. Evidence of each renewal or replacement of a policy shall be
delivered by Tenant to Landlord at least five (5) days prior to the expiration
of such policy. In lieu of the policy of insurance required to be delivered to
Landlord pursuant to this Article 12 (the "Policy"), Tenant may deliver to
Landlord a certification from Tenant's insurance company (on the form currently
designated "Accord 27," or the equivalent, rather than on the form currently
designated "Accord 25-S," or the equivalent) which shall be binding on Tenant's
insurance company, and which shall expressly provide that such certification (i)
conveys to Landlord and any other named insured and/or additional insureds
thereunder (the

                                      -40-

<PAGE>

"Insured Parties") all the rights and privileges afforded under the Policy as
primary insurance, and (ii) contains an unconditional obligation of the
insurance company to advise all Insured Parties in writing at least thirty (30)
days in advance of any termination or change to the Policy that would affect the
interest of any of the Insured Parties.

      Section 12.2  Landlord's Insurance.
                    --------------------

                    (a)  During the construction of the Base Building Work and
continuing until the completion thereof, Landlord shall maintain, at Landlord's
expense, builder's risk insurance on an "all risk" basis and on a completed
value form including a Permission to Complete and Occupy endorsement, for full
replacement value covering the interest of Landlord and Tenant, as their
interests may appear, in all work incorporated in the Building and all materials
and equipment in or about the Premises.

                    (b)  Throughout the Term, Landlord shall maintain,  as an
Operating Expense, standard All Risk Coverage insurance on the Premises,
including the Base Building, Initial Installations and subsequent Alterations
and any improvements and betterments which may be made on behalf of or paid by
the Tenant to the extent that same are customarily insurable as part of the
realty (but excluding Tenant Property and Specialty Alterations) insuring
against such perils as are insured against under such policies for the full
replacement cost thereof; provided, however, Landlord shall only be required to
maintain insurance for Initial Installations and Alterations to the extent
Tenant has provided Landlord the Initial Installations Construction Documents,
the construction documents for any Alteration, and reasonably detailed schedules
reasonably satisfactory to Landlord's insurer, describing the property to be
insured. Without limitation, such insurance shall include: (i) insurance on the
Building and other improvements and Landlord's property therein against fire and
casualty and other risks as may be included in all-risk coverage casualty
insurance in an amount equal to full replacement cost of the Building and the
Parking Garage (exclusive of footings and foundations), and rent loss insurance
protecting Landlord against abatement or loss of rent in an amount equal to the
Rent paid by Tenant under this Lease for a period of eighteen (18) months; (ii)
commercial general liability insurance on an occurrence basis against claims for
bodily injury (including death) and for property damage occurring in or about
the Premises for which the Landlord is legally liable and including actions of
the employees, contractors, subcontractors, invitees, agents and others working
on behalf of the Landlord, under which Landlord is named as the insured and
Tenant is named as additional insured; (iii) broad form boiler and machinery
insurance covering property damage; (iv) blanket, broad-form contractual
liability coverage to insure Landlord's indemnity obligations set forth in
Article 29 hereof; and (v) such other insurance as it is or may become customary
----------
for owners of Comparable Buildings to carry for loss of or damage to the
property, or liability arising therefrom. If the aggregate limit of such
coverage is reduced by the payment of a claim or establishment of a reserve
equal to or greater than fifty percent (50%) of the annual aggregate, Landlord
shall immediately arrange to have the aggregate limit restored by endorsement to
the existing policy or the purchase of an additional insurance policy unless,
Landlord maintains sufficient excess liability

                                       -41-

<PAGE>

insurance with a "drop-down" endorsement to satisfy the liability requirements
of this Lease without the reinstatement of the aggregate limit;

                    (c)  All insurance required to be carried by Landlord
pursuant to the terms of this Lease (i) shall contain a provision that (x) only
material statements or acts that would ordinarily void or suspend coverage will
adversely affect the rights of the offending party, (y) the policy shall be
noncancellable and/or no material change in coverage shall be made thereto
unless Tenant and Mortgagees and Lessors which are additional insureds or loss
payees thereunder shall have received thirty (30) days prior notice of the same,
and (z) Landlord shall be solely responsible for the payment of all premiums
under such policies and Tenant and Mortgagees and Lessors shall have no
obligation for the payment thereof, and (ii) shall be effected under valid and
enforceable policies issued by reputable and independent insurers authorized to
do business in the Commonwealth of Virginia and rated in Best's Insurance Guide,
or any successor thereto (or if there be none, an organization having a national
reputation), as having a "Best's Rating" of "A-" or better and "Financial Size
Category" of at least X or, if such ratings are not then in effect, the
reasonable equivalent thereof. The deductible on Landlord's All Risk Coverage
Insurance shall not exceed Twenty-Five Thousand Dollars ($25,000) or such
greater amount as may customarily be accepted from time to time by prudent
owners of Comparable Buildings.

                    (d)  The actual cost of premiums for all insurance
maintained by Landlord (other than builders risk insurance) pursuant to the
foregoing subsection (b) shall be included in Operating Expenses.

                    (e)  On or prior to the initial Rent Commencement Date,
Landlord shall deliver to Tenant appropriate policies or certificates of
insurance, including evidence of waivers of subrogation required to be carried
by each party pursuant to this Article 12. Evidence of each renewal or
                               ----------
replacement of a policy shall be delivered by Landlord to Tenant at least five
(5) days prior to the expiration of such policy.

      Section 12.3  Other. In the event either party does not procure the
                    -----
insurance required to be procured by such party (the "Deficient Party") under by
this Lease, or keep the same in full force and effect, and the same is not
corrected within five (5) Business Days following actual receipt of written
notice thereof from the other party (the "Notifying Party"), then the Notifying
Party may, but shall not be obligated to, purchase the necessary insurance and
pay the premium. The Deficient Party shall repay to the Notifying Party any and
all reasonable expenses (including attorneys' fees) and damages which the
Notifying Party may sustain by reason of the failure of the Deficient Party to
obtain and maintain such insurance.

      Section 12.4  Umbrella Coverage. Notwithstanding anything to the
                    -----------------
contrary contained in Section 12.1 or Section 12.2, Landlord's or Tenant's
obligations to maintain the insurance therein required may be brought within the
coverage of a so-called blanket policy or policies of insurance together with
other properties owned by Landlord or Landlord's Affiliates or Tenant or
Tenant's Affiliates, as the case may be, provided that, except as otherwise
approved by the other party hereto in writing, (a) the coverage

                                      -42-

<PAGE>

thereby afforded will not be reduced or diminished from that which would exist
under a separate policy meeting all other requirements of this Lease, and (b)
with respect to Landlord, only that portion of the costs of such insurance
appropriately allocable to the Premises shall be included in Operating Expenses.

      Section 12.5  Waiver of Subrogation. Landlord and Tenant shall each
                    ---------------------
procure an appropriate clause in or endorsement to any property insurance
covering the Premises and personal property, fixtures and equipment located
therein, wherein the insurance companies shall waive subrogation or consent to a
waiver of right of recovery, and Landlord and Tenant agree not to make any claim
against, or seek to recover from, the other for any loss or damage to its
property or the property of others resulting from fire or other hazards to the
extent covered by such property insurance; provided, however, that the release,
discharge, exoneration and covenant not to sue contained herein shall be limited
by and coextensive with the terms and provisions of the waiver of subrogation or
waiver of right of recovery. If either party shall be unable to obtain the
inclusion of such clause even with the payment of a reasonable additional
premium, including from an alternative insurer (except in the case of blanket
coverage), then such party shall attempt to name the other party as a loss payee
under the policy. If it shall not be possible to have the other party named as a
loss payee, even with the payment of a reasonable additional premium, then the
first (1st) party shall not be required to obtain such waiver of subrogation or
consent to waiver provision and such party shall so notify the first (1st) party
and the first (1st) party's agreement to name the other party as an additional
insured shall, except as otherwise expressly provided herein, be satisfied.
Tenant acknowledges that Landlord shall not carry insurance on, and shall not be
responsible for, (i) Tenant's Property and Specialty Alterations, and (ii) any
loss suffered by Tenant due to interruption of Tenant's business. Landlord
acknowledges that Tenant shall not carry insurance on, and shall not be
responsible for, any loss suffered by Landlord due to interruption of Landlord's
business.

                                   ARTICLE 13
                        DESTRUCTION - FIRE OR OTHER CAUSE
                        ---------------------------------

      Section 13.1  Restoration. If the Premises are damaged by fire or other
                    -----------
casualty, or if the Building or Parking Garage is damaged such that Tenant is
deprived of reasonable access thereto, the damage shall be repaired by Landlord,
at its expense, to substantially the condition of the Premises prior to the
damage, subject to customary requirements of any Mortgage or Superior Lease
regarding placement of proceeds into trust, submitting requisitions, etc., but
Landlord shall have no obligation to repair or restore (i) Tenant's Property or
(ii) except as provided in this Article 13, any Alterations to the Premises, to
                                ----------
the extent such Alterations exceed the Minimum Build-Out Standards set forth on
Schedule C-4 of the Design and Construction Agreement ("Above Building Standard
------------
Installations"). Provided no uncured Material Default shall then exist, and
provided Tenant timely delivers to Landlord either Tenant's Restoration Payment
(as hereinafter defined) or the Restoration Security (as hereinafter defined) or
Tenant expressly waives any obligation of Landlord to repair or restore any of
Tenant's Above Building Standard Installations, then until the restoration of
the Premises is Substantially Completed or would have been Substantially
Completed but for Tenant

                                      -43-

<PAGE>

Delay, Fixed Rent, Tenant's Tax Payment and Tenant's Operating Expense Payment
shall be reduced in the proportion by which the Agreed Area of the part of the
Building which is not usable (or accessible) and is not used by Tenant in the
ordinary course bears to the total area of the Building.

      As a condition precedent to Landlord's obligation to repair or restore any
of Tenant's Above Building Standard Installations, Tenant shall (i) pay to
Landlord upon demand a sum ("Tenant's Restoration Payment") equal to the amount,
if any, by which (A) the cost, as estimated by a reputable independent
contractor designated by Landlord, of repairing and restoring all Alterations in
the Premises to their condition prior to the damage, exceeds (B) the cost of
restoring the Premises with Minimum Build-Out Installations, or (ii) furnish to
Landlord security (the "Restoration Security") in form and amount reasonably
acceptable to Landlord to secure Tenant's obligation to pay all costs in excess
of restoring the Premises with Minimum Build-Out Installations. If Tenant shall
fail to deliver to Landlord either (1) Tenant's Restoration Payment or the
Restoration Security, as applicable, or (2) a written waiver by Tenant of all of
Landlord's obligations to repair or restore any of the Above Building Standard
Installations, in either case within fifteen (15) days after Landlord's demand
therefor, Tenant's abatement of Fixed Rent, Tenant's Tax Payment and Tenant's
Operating Expense Payment shall cease commencing as of the sixteenth (16th) day
after Landlord's demand, and shall resume upon delivery to Landlord of Tenant's
Restoration Payment or the Restoration Security, or such written waiver, as the
case may be. Nothing set forth in this Section 13.1 shall be interpreted to
limit Landlord's right to repair or restore all or any portion of the Premises
at such time and in such manner as Landlord deems appropriate, and no such
repair or restoration shall constitute a waiver by Landlord of any of Landlord's
rights set forth in this Section 13.1 or elsewhere in this Lease.

      Section 13.2  Landlord's Termination Right. Notwithstanding anything to
                    ----------------------------
the contrary contained in Section 13.1, if the Premises are totally damaged or
are rendered wholly untenantable, then in either of such events, Landlord may,
not later than sixty (60) days following the date of the damage, terminate this
Lease by notice to Tenant, provided that if the Premises are not damaged,
Landlord may not terminate this Lease unless Landlord similarly terminates the
leases of other tenants in the Building (if any) aggregating at least 50% of the
portion of the Building occupied for office purposes immediately prior to such
damage. If this Lease is so terminated, (a) the Term shall expire upon the
thirtieth (30th) day after such notice is given, (b) Tenant shall vacate the
Premises and surrender the same to Landlord, (c) Tenant's liability for Rent
shall cease as of the date of the damage, and (d) any prepaid Rent for any
period after the date of the damage shall be refunded by Landlord to Tenant.

      Section 13.3  Tenant's Termination Right. If the Premises (or any portion
                    --------------------------
thereof) are damaged and are thereby rendered wholly untenantable, or if the
Building or Parking Garage shall be so damaged that Tenant is deprived of
reasonable access thereto, and if Landlord does not terminate pursuant to
Section 13.2, Landlord shall, within sixty (60) days following the date of the
damage, cause a contractor or architect selected by Landlord to give notice (the
"Restoration Notice") to Tenant of the date by which such contractor or
architect estimates the restoration of the Premises (excluding

                                      -44-

<PAGE>

any Above Building Standard Installations) shall be Substantially Completed. If
such date, as set forth in the Restoration Notice, is more than eighteen (18)
months from the date of such damage (with no extension for force majeure), or if
Landlord fails to timely provide the Restoration Notice, then Tenant shall have
the right to terminate this Lease by giving notice (the "Termination Notice") to
Landlord not later than thirty (30) days following delivery of the Restoration
Notice to Tenant. If Tenant delivers a Termination Notice, this Lease shall be
deemed to have terminated as of the date of the giving of the Termination
Notice.

      Section 13.4  Final Eighteen (18) Months. Notwithstanding anything set
                    --------------------------
forth to the contrary in this Article 13, in the event that any damage rendering
                              ----------
the Building or Premises wholly untenantable occurs during the final eighteen
(18) months of the Term (as the same may then have been extended pursuant to
Article 31), either Landlord or Tenant may terminate this Lease by notice to the
----------
other party within thirty (30) days after the occurrence of such damage and this
Lease shall expire on the thirtieth (30th) day after the date of such notice.
For purposes of this Article 13, the Premises shall be deemed "wholly
                     ----------
untenantable" if due to such damage, Tenant shall be precluded from using more
than fifty percent (50%) of the Premises for the conduct of its business and
Tenant's inability to so use the Premises is reasonably expected to continue
until at least the earlier of the (a) Expiration Date and (b) the one hundred
eightieth (180th) day after the date when such damage occurs.

      Section 13.5  Landlord's Liability. None of Landlord, its agents or any
                    --------------------
Mortgagee or Lessor shall be liable for any injury or damage to persons or
property or interruption of Tenant's business resulting from fire or other
casualty, any damage caused by other tenants or persons in the Building or by
construction of any private, public or quasi-public work, or any latent defect
in the Premises (except to the extent expressly provided in this Article 13 or
                                                                 ----------
elsewhere in this Lease). No penalty shall accrue for delays which may arise by
reason of adjustment of fire insurance on the part of Landlord or Tenant, or for
Unavoidable Delay arising from any repair or restoration of any portion of the
Premises, provided that Landlord shall use reasonable efforts to minimize
interference with Tenant's use and occupancy of the Premises during the
performance of any such repair or restoration, provided that Landlord shall have
no obligation to employ contractors or labor at overtime or other premium pay
rates or to incur any other overtime costs or additional expenses whatsoever,
unless requested by Tenant and then at Tenant's sole expense.

                                   ARTICLE 14
                                 EMINENT DOMAIN
                                 --------------

      Section 14.1  (a)  Total Taking.  If all or substantially all of the
                         ------------
Premises shall be acquired or condemned for any public or quasi-public purpose,
other than on a temporary basis, this Lease shall terminate and the Term shall
end as of the date of the vesting of title, with the same effect as if such date
were the Expiration Date, and Rent shall be prorated and adjusted as of such
date.

                                      -45-

<PAGE>

                    (b)  Partial Taking.  If only a part of the Premises shall
                         --------------
be acquired or condemned then, except ashereinafter provided in this Article 14,
                                                                     ----------
this Lease and the Term shall continue in full force and effect, provided that
from and after the date of the vesting of title, the Rent shall be equitably
reduced to reflect the reduction of the Premises as a result of such acquisition
or condemnation.

                    (c)  Tenant's Termination Right.  If (i) the part of the
                         --------------------------
Premises so acquired or condemned contains more than twenty-five percent (25%)
of the total area of the Building or more than twenty-five percent (25%) of the
total parking spaces (unless other parking reasonably satisfactory to Tenant is
arranged by Landlord) immediately prior to such acquisition or condemnation and
such condemnation lasts for a period of 120 days, or (ii) if, by reason of such
acquisition or condemnation, Tenant no longer has reasonable means of access to
the Premises (including the Building and the Parking Garage) for more than 120
consecutive days, then Tenant may terminate this Lease by notice to Landlord
given within thirty (30) days following the date upon which Tenant received
notice of such acquisition or condemnation. If Tenant so notifies Landlord, this
Lease shall end and expire upon the thirtieth (30/th/) day following the giving
of such notice. If a part of the Premises shall be so acquired or condemned and
this Lease and the Term shall not be terminated in accordance with this Section
14.1 Landlord, at Landlord's expense, but without requiring Landlord to spend
more than it collects as an award, shall, subject to the provisions of any
Mortgage or Superior Lease, restore that part of the Premises not so acquired or
condemned to a self-contained rental unit as substantially equivalent as
reasonably possible (with respect to character, quality, appearance and
services) to that which existed immediately prior to such acquisition or
condemnation, excluding Tenant's Property and/or Specialty Alterations and Fixed
Rent shall be equitably reduced for the balance of the Term. Notwithstanding the
foregoing, in the event that the portion of the Premises to be restored or
reconstructed exceeds twenty-five percent (25%) of the total rentable square
feet of the Building, Landlord shall not be obligated to restore or reconstruct
the Premises following condemnation unless Tenant so requests and (i) Landlord
is able to finance the cost of such restoration or reconstruction upon
commercially reasonable terms and within one hundred eight (180) days after
Landlord initiates (and thereafter diligently pursues) its attempt to secure
such financing, including obtaining a commitment therefor, and (ii) if the
balance of the Term then remaining is less than ten (10) years, Tenant,
simultaneously with such request, agrees to extend the Term of the Lease for the
next unexercised Extension Period or, if the Term is then in the last Extension
Period, for an additional period as will provide a term of ten (10) years from
the date of such request.

                    (d)  Apportionment of Rent.  Upon any termination of this
                         ---------------------
Lease pursuant to the provisions of this Article 14, Rent shall be apportioned
                                         ----------
as of, and shall be paid or refunded up to and including, the date of such
termination. This provision shall survive expiration or earlier termination of
the Lease.

      Section 14.2  Awards. Upon any acquisition or condemnation of all or any
                    ------
part of the Premises, Landlord shall receive the entire award for any such
acquisition or condemnation, and Tenant shall have no claim against Landlord or
the condemning

                                      -46-

<PAGE>

authority for the value of any unexpired portion of the Term; and Tenant hereby
assigns to Landlord all of its right in and to such award. Nothing contained in
this Article 14 shall be deemed to prevent Tenant from making a separate claim
     ----------
in any condemnation proceedings for the then value of any Tenant's Property or
Alterations paid for by Tenant included in such taking and for any moving
expenses or business interruption, provided any such award is in addition to,
and does not result in a reduction of, the award made to Landlord.

      Section 14.3  Temporary Taking. If all or any part of the Premises is
                    ----------------
acquired or condemned for less than 120 days during the Term for any public or
quasi-public use or purpose, Tenant shall give prompt notice to Landlord and the
Term shall not be reduced or affected in any way and Tenant shall perform all of
its other obligations under this Lease, except to the extent prevented from
doing so by the condemning authority, provided that Rent shall be proportionally
abated for the amount of time any such part of the Premises is unusable by
Tenant and Tenant shall be entitled to receive any award or payment from the
condemning authority for such use.

                                   ARTICLE 15
                            ASSIGNMENT AND SUBLETTING
                            -------------------------

      Section 15.1  (a)  Permitted Transfer.
                         ------------------

                         (i)  Notwithstanding any other provision hereof to the
contrary, provided Tenant is leasing one hundred percent (100%) of the Agreed
Area of the Building and no uncured Material Default shall exist at the time
Tenant enters into an agreement to sublease, Landlord's consent shall not be
required (and no profits shall be shared) in the event that the area of any
proposed sublease, when combined with the area of all portions of the Premises
then under sublease (exclusive of all areas of the Premises subleased to
Affiliates of Tenant), does not exceed 100,000 rentable square feet of the
Building (the "Threshold"). Upon request, Tenant shall provide Landlord with
prompt notice of any subleases beneath the Threshold.

                         (ii) Tenant may also, at any time and from time to
time, without the consent of Landlord (and without profit sharing), permit any
Tenant Affiliate to sublet all or part of the Premises, or take an assignment of
this Lease, for any Permitted Use. Such sublease or assignment shall not
relieve, release, impair or discharge any of Tenant's obligations hereunder.
Upon request by Landlord from time to time, Tenant shall provide a list of all
Tenant Affiliates then occupying any portion of the Premises, such list to be
certified by Tenant as being true and correct.

                    (b)  Restricted Assignment or Subletting.  Except as
                         -----------------------------------
expressly set forth in Section 15.1(a) above, Tenant shall not assign, mortgage,
pledge, encumber, or otherwise transfer this Lease, whether by operation of law
or otherwise, and shall not sublet (or underlet), or permit the Premises or any
part thereof to be used or occupied by others (whether for desk space, mailing
privileges or otherwise), without Landlord's prior consent in each instance,
which consent shall be granted or withheld in

                                      -47-

<PAGE>

accordance with Section 15.3 hereof. Any assignment, sublease, mortgage, pledge,
encumbrance or transfer in contravention of the provisions of this Article 15
                                                                   ----------
shall be void.

                    (c)  Collection of Rent. If, without Landlord's consent
                         ------------------
where Landlord's consent is required, thisLease is assigned, or any part of the
Premises is sublet or occupied by anyone other than Tenant, or this Lease or the
Premises is encumbered (by operation of law or otherwise), Landlord may collect
rent from the assignee, subtenant or occupant, and shall apply the net amount
collected to the Rent herein reserved. No such collection shall be deemed a
waiver of the provisions of this Article 15, an acceptance of the assignee,
                                 ----------
subtenant or occupant as tenant, or a release of Tenant from the performance of
Tenant's covenants hereunder. Tenant shall remain fully liable for the
obligations under this Lease.

                    (d)  Further Assignment/Subletting.  Landlord's consent to
                         -----------------------------
any assignment or subletting shall not relieve Tenant from the obligation to
obtain Landlord's express consent to any further assignment or subletting when
required pursuant to this Lease, or to any modifications or amendments to
previously approved assignments or subleases if such consent would have been
required had such sublease been a new sublease, as to which Landlord shall not
unreasonably withhold, delay or condition its consent.

      Section 15.2  Tenant's Notice. If Tenant desires to assign this Lease or
                    ---------------
sublet all or any portion of the Premises to a Person, other than pursuant to
Section 15.1(a), Tenant shall give prior written notice thereof to Landlord
("Tenant's Notice"), which shall be accompanied by (a) with respect to an
assignment of this Lease, the date Tenant desires the assignment to be
effective, (b) with respect to a sublet of all or a part of the Premises, (i)
the material business terms on which Tenant would sublet such premises and (ii)
a description of the portion of the Premises to be sublet, and (c) a true and
complete statement reasonably detailing the identity of the proposed assignee or
subtenant, the nature of its business and its proposed use of the Premises, and
reasonably current financial information with respect to the proposed assignee
or subtenant, including its most recent financial statements, if such exist.
Tenant's notice shall state in a conspicuous fashion that the failure to respond
within eleven (11) Business Days after receipt or deemed receipt will constitute
consent to the proposal sublease or assignment.

      Section 15.3  Conditions to Assignment/Subletting.
                    -----------------------------------

                         (a)  Provided no uncured Material Default shall then
      exist, in any case in which Landlord's consent to an assignment or
      subletting is required, such consent shall not be unreasonably withheld,
      conditioned or delayed beyond eleven (11) Business Days after Landlord's
      receipt of Tenant's Notice, provided that:

                              (i)  Tenant shall, within thirty (30) days after
      demand, reimburse Landlord for all reasonable expenses incurred by
      Landlord in

                                      -48-

<PAGE>

      connection with such assignment or sublease, including any investigations
      as to the acceptability of the proposed assignee or subtenant, reviewing
      any plans and specifications for Alterations proposed to be made in
      connection therewith, and all reasonable legal costs incurred in
      connection with the granting of any requested consent (such reimbursement
      shall not exceed $2,500 per transaction); and

                        (ii)   the proposed subtenant or assignee shall not be
      entitled to diplomatic or sovereign immunity, which such subtenant or
      assignee has not waived.

               If Landlord fails to respond within such eleven (11) Business
Days after Tenant's request, then Tenant's request shall be deemed approved. Any
assignee of this Lease that meets the Secondary Financial Condition, and any
Tenant Affiliate, shall maintain all of the rights and options (including
renewal, expansion, signage, etc.) contained in this Lease in favor of Tenant.
Landlord acknowledges that Tenant's rights and options shall continue
notwithstanding any permitted sublease and whether Tenant may exercise same for
its own use or as an accommodation to its subtenant.

               (b)  With respect to each and every subletting and/or assignment
consented to, or deemed consented to, by Landlord under the provisions of this
Lease, it is further agreed that:

                    (i)   the form of the proposed instrument of assignment or
sublease shall be reasonably satisfactory to Landlord and Tenant and shall
comply with the provisions of this Article 15;
                                   ----------

                    (ii)  no sublease shall be for a term ending later than one
(1) day prior to the Expiration Date of this Lease;

                    (iii) no subtenant requiring Landlord's consent shall take
possession of any part of the Premises until an executed counterpart of such
sublease has been delivered to Landlord;

                    (iv)  each sublease shall be subject and subordinate to this
Lease and to the matters to which this Lease is or shall be subordinate, it
being the intention of Landlord and Tenant that Tenant shall assume and be
liable to Landlord for any and all acts and omissions of all subtenants and
anyone claiming under or through any subtenants which, if performed or omitted
by Tenant, would be a default under this Lease; and

     (v)   Upon request, Tenant shall provide Landlord with a copy of any
marketing materials produced by or for Tenant which publicize the availability
of all or any portion of the Premises.

     Section 15.4 Binding on Tenant; Indemnification of Landlord. Each sublease
                  ----------------------------------------------
pursuant to this Article 15 shall be subject to all of the covenants, terms and
                 ----------
conditions

                                      -49-

<PAGE>

of this Lease. Notwithstanding any assignment or subletting or any acceptance of
Rent by Landlord from any assignee or subtenant, and irrespective of whether or
not such assignments or sublettings required Landlord's consent, Tenant shall
remain fully liable for the payment of all Rent due and for the performance of
all the covenants, terms and conditions contained in this Lease on Tenant's part
to be observed and performed. Tenant shall indemnify, defend, protect and hold
harmless Landlord from and against any and all losses, liabilities, damages and
expenses (including reasonable attorneys' fees and disbursements) resulting from
any claims that may be made against Landlord by any brokers or other Persons
claiming a commission or similar compensation in connection with the proposed
assignment or sublease, irrespective of whether Landlord shall give or decline
to give its consent to any proposed assignment or sublease in accordance with
this Lease, or if Landlord shall exercise any of its options under this Article
                                                                        -------
15.
--

     Section 15.5 Tenant's Failure to Complete. If Landlord consents to a
                  ----------------------------
proposed assignment or sublease and Tenant fails to execute and deliver to
Landlord such assignment or sublease within one (1) year after the giving of
such consent, then Tenant shall again comply with all of the provisions and
conditions of Section 15.2 hereof before assigning this Lease or subletting all
or part of the Premises.

     Section 15.6 Profits. If Tenant shall enter into any assignment or sublease
                  -------
permitted hereunder or consented to by Landlord (other than those to an
Affiliate of Tenant or those with square footage to the extent below the
Threshold), Tenant shall promptly, but in any event within thirty (30) days
following the execution and delivery of such assignment or sublease, deliver to
Landlord a complete list of Tenant's reasonable third-party brokerage fees,
legal fees and architectural fees paid or to be paid in connection with such
transaction, together with a list of all of Tenant's Property to be transferred
to such assignee or sublessee. Tenant shall deliver to Landlord evidence of the
payment of such fees promptly after the same are paid. In consideration of an
assignment or subletting of one or more Floors to other than Tenant Affiliate
(or portion of same) to the extent Tenant exceeds the Threshold, Tenant shall
pay to Landlord:

                  (a)   In the case of an assignment (other than to Tenant
Affiliate), on the effective date of the assignment, an amount equal to fifty
percent (50%) of all sums and other consideration (limited to rent or other sums
that are not intended to be a disguised rental or sale amount, such as a
reasonable furniture allowance, a reasonable technology fee, reasonable amenity
usage fees, etc.) paid to Tenant by the assignee for or by reason of such
assignment (including sums paid for the sale or rental of Tenant's Property
which are intended to be a disguised sale or rental amount, less, in the case of
a sale thereof, the then undepreciated value thereof as shown on Tenant's most
recent tax returns and goodwill), after first deducting (i) Tenant's reasonable
third-party brokerage fees, legal fees and architectural fees, (ii) the cost of
rental concessions and tenant improvement allowances, (iii) the unamortized
portion of Tenant's out-of-pocket costs for tenant improvements in such space in
excess of Landlord's Contribution applicable to such space, (iv) the amount of
prorated Rent applicable to such space paid during any period that such space is
vacant, as certified

                                      -50-

<PAGE>

in writing by Tenant, and is being actively marketed by Tenant (provided Tenant
has previously notified Landlord of its intent to assign), and (v) other costs,
fees and expenses reasonably incurred in connection with such transaction.

                  (b)   In the case of a sublease (other than to Tenant
Affiliate), fifty percent (50%) of any consideration (limited to rent or other
sums that are not intended to be a disguised rental or sale amount, such as a
reasonable furniture allowance, a reasonable technology fee, reasonable amenity
usage fees, etc.) payable under the sublease to Tenant by the subtenant which
exceeds on a per square foot basis the Fixed Rent and Additional Rent accruing
during the term of the sublease in respect of the subleased space (together with
any sums paid for the sale or rental of Tenant's Property which are intended to
be a disguised sale or rental amount, less, in the case of the sale thereof, the
then undepreciated value thereof as shown on Tenant's most recent tax returns
and goodwill) after first deducting (i) Tenant's reasonable third-party
brokerage fees, legal fees and architectural fees, (ii) the cost of rental
concessions and tenant improvement allowances, (iii) the unamortized portion of
Tenant's out-of-pocket costs for tenant improvements in such space in excess of
Landlord's Contribution applicable to such space, (iv) the amount of prorated
Rent applicable to such space paid during any period that such space is vacant,
as certified in writing by Tenant, and is being actively marketed by Tenant
(provided Tenant has previously notified Landlord of its intent to sublease),
and (v) other costs, fees and expenses reasonably incurred in connection with
such transaction, and if such sublease is less than the entire Premises, the
actual cost incurred by Tenant in separately demising the subleased space. The
sums payable under this clause shall be paid by Tenant to Landlord as and when
paid by the subtenant to Tenant. Such costs shall be amortized over the term of
the sublease.

     Section 15.7 (a) Transfers. If Tenant is a corporation, the transfer (by
                      ---------
one or more related transfers within a 6-month period) of a majority of the
stock of Tenant shall be deemed a voluntary assignment of this Lease; provided,
however, that, notwithstanding anything to the contrary set forth in this
Section 15.7, the provisions of this Article 15 shall not apply to the transfer
                                     ----------
of shares of stock or partnership, membership or other beneficial ownership
interests of Tenant if and so long as Tenant is publicly traded on a nationally
recognized stock exchange, or is listed on the NASDAQ Stock Market, immediately
prior to such transfer. For purposes of this Section 15.7 the term "transfers"
shall be deemed to include the issuance of new stock which results in a majority
of the stock of Tenant being held by a Person which does not hold a majority of
the stock of Tenant on the date of such assignment or deemed assignment. If
Tenant is a partnership (which, as of the date hereof, Tenant is not), the
transfer (by one or more transfers) of a majority interest in the partnership
shall be deemed a voluntary assignment of this Lease. If Tenant is a limited
liability company, trust, or any other legal entity (which, as of the date
hereof, Tenant is not), the transfer (by one or more transfers) of a majority of
the beneficial ownership interests in such entity, however characterized, shall
be deemed a voluntary assignment of this Lease. The provisions of Section 15.1
shall not apply to transactions with Affiliates so long as such transfer was
made for a legitimate independent business purpose and not

                                      -51-

<PAGE>

for the purpose of transferring this Lease in order to avoid consent or profit
rights of Landlord.

          (b)   [Intentionally Deleted.]

          (c)   Modifications. Any modification, amendment or extension of a
                -------------
sublease, as to which Landlord shall not unreasonably withhold, delay or
condition its consent, shall be deemed a sublease for the purposes of Section
15.1 hereof.

     Section 15.8 Partnership Tenant. Landlord acknowledges that (a) so long as
                  ------------------
Tenant or a permitted assignee of Tenant is not a partnership, this Section
shall be deemed to be inapplicable; and (b) as of the date hereof, Tenant is a
corporation and not a partnership. If Tenant, or a permitted assignee of this
Lease pursuant to this Article 15 hereof, is a partnership, or is comprised of
                       ----------
two or more Persons, individually or as co-partners of a partnership (any such
partnership and such Persons are referred to in this Article 15 as "Partnership
                                                     ----------
Tenant"), the following shall apply: (a) the liability of each of the general
partners comprising Partnership Tenant shall be joint and several; (b) each of
the parties comprising Partnership Tenant hereby consents in advance to, and
agrees to be bound by, any written instrument which may hereafter be executed by
Partnership Tenant or any of the parties comprising Partnership Tenant, which
shall modify, extend or discharge this Lease, in whole or in part, or surrender
all or any part of the Premises to Landlord; (c) any bills, statements, notices,
demands, requests or other communications given or rendered to Partnership
Tenant or to any of such parties shall be binding upon Partnership Tenant and
all such partners; (d) if Partnership Tenant shall admit new general partners,
all of such new general partners shall, by their admission to Partnership
Tenant, be deemed to have assumed joint and several liability for the
performance of all of the terms, covenants and conditions of this Lease on
Tenant's part to be observed and performed; (e) Partnership Tenant shall give
prompt notice to Landlord of the admission of any such new general partners, and
upon demand of Landlord, shall cause each such new partner to execute and
deliver to Landlord an agreement in form and substance reasonably satisfactory
to Landlord, wherein each such new partner shall assume joint and several
liability for the performance of all the terms, covenants and conditions of this
Lease on Tenant's part to be observed and performed (but neither Landlord's
failure to request any such agreement nor the failure of any such new partner to
execute or deliver any such agreement to Landlord shall vitiate the provisions
of this Section 15.8(e); and (f) no change in the partners of Partnership Tenant
resulting from the admission of a new partner, or the death, retirement or
withdrawal of a partner shall release Partnership Tenant or any partner or
former partner from their obligations under this Lease.

     Section 15.9 Change of Partners. Landlord acknowledges that (a) so long as
                  ------------------
Tenant or a permitted assignee of Tenant is not a partnership, this Section
shall be deemed to be inapplicable; and (b) as of the date hereof, Tenant is a
corporation and not a partnership. If Tenant is a partnership, (a) the admission
of new partners, the withdrawal, retirement, death, incompetency or bankruptcy
of any partner, or the reallocation of partnership interests among the partners
of Tenant (the "Partners") shall not constitute an assignment of this Lease
provided that Partners holding in the

                                      -52-

<PAGE>

aggregate not less than eighty percent (80%) of the partnership interests in
Tenant remain as Partners during any consecutive twelve (12) month period (i.e.,
the transfer, by any of the foregoing means, of more than twenty percent (20%)
of the partnership interests in Tenant in any consecutive twelve (12) month
period shall constitute an assignment of this Lease subject to the provisions of
Section 15.1), and (b) the reorganization of Tenant into a professional
corporation or a limited liability partnership, or the reorganization of Tenant
from a professional corporation or a limited liability partnership into a
partnership, shall not constitute an assignment of this Lease, provided that
immediately following such reorganization the partners, members or shareholders,
as the case may be, of Tenant shall be the same as those existing immediately
prior to such reorganization, and shall remain fully, jointly and severally
liable under this Lease as provided in this Section 15.9. If Tenant shall become
a professional corporation, each individual shareholder, shareholder-employee,
new individual shareholder and new shareholder-employee of any professional
corporation which is a shareholder in Tenant shall have the same personal
liability (if any) as such individual or shareholder-employee would have under
this Lease if Tenant were a partnership and such individual or
shareholder-employee were a Partner or admitted as a new Partner. If any
individual Partner in Tenant is or becomes a shareholder-employee of a
professional corporation, such individual shall have the same personal liability
under this Lease as such individual would have if he and not the professional
corporation were a Partner of Tenant. If Tenant shall become a limited liability
partnership, (i) each partner therein shall continue to have the same personal
liability as such partner had under this Lease prior to Tenant becoming a
limited liability partnership, and (ii) each new partner admitted to such
limited liability partnership shall be bound by the provisions of Section 15.8,
and shall execute and deliver to Landlord the assumption agreement required
pursuant to Section 15.8(e) hereof.

     Section 15.10 Assumption of Obligations. Any assignment or transfer,
                   -------------------------
whether made with Landlord's consent or without Landlord's consent, if and to
the extent permitted hereunder, shall not be effective unless and until the
assignee executes and delivers to Landlord an agreement in form and substance
reasonably satisfactory to Landlord whereby the assignee (a) assumes Tenant's
obligations under this Lease and (b) agrees that, notwithstanding such
assignment or transfer, the provisions of Section 15.1 hereof shall be binding
upon it in respect of all future assignments and transfers.

     Section 15.11 Tenant's Liability. The joint and several liability of Tenant
                   ------------------
and any successors-in-interest of Tenant and the due performance of Tenant's
obligations under this Lease shall not be discharged, released or impaired by
(a) any assignment or subletting of this Lease or the Premises, whether or not
permitted by this Article 15, or (b) any agreement or stipulation made by
                  ----------
Landlord, or any grantee or assignee of Landlord, extending the time, or
modifying any of the terms and provisions of this Lease, or by any waiver or
failure of Landlord, or any grantee or assignee of Landlord, to enforce any of
the terms and provisions of this Lease.

     Section 15.12 Listings in Building Directory. The listing of any name other
                   ------------------------------
than that of Tenant on the doors of the Premises, the Building directory or
elsewhere shall

                                      -53-

<PAGE>

be permitted without Landlord's consent for all parties rightfully in possession
of any portion of the Premises but shall not vest any right or interest in this
Lease or in the Premises, nor be deemed to constitute Landlord's consent to any
assignment or transfer of this Lease or to any sublease of the Premises or to
the use or occupancy thereof by others.

     Section 15.13 Lease Disaffirmance or Rejection. If at any time after an
                   --------------------------------
assignment by Tenant named herein, this Lease is not affirmed or is rejected in
any proceeding of the types described in Sections 17.1(e) and (f) hereof or any
similar proceeding, or upon a termination of this Lease due to any such
proceeding, Tenant named herein, upon request of Landlord given after such
disaffirmance, rejection or termination (and actual notice thereof to Landlord
in the event of a disaffirmance or rejection or in the event of termination
other than by act of Landlord), shall (a) pay to Landlord all Rent and other
charges due and owing by the assignee to Landlord under this Lease to and
including the date of such disaffirmance, rejection or termination, and (b) as
"tenant," enter into a new lease of the Premises with Landlord for a term
commencing on the effective date of such disaffirmance, rejection or termination
and ending on the Expiration Date, unless sooner terminated in accordance
therewith, at the same Rent and upon the then executory terms, covenants and
conditions contained in this Lease, except that (i) the rights of Tenant named
herein under the new lease shall be subject to the possessory rights of the
assignee under this Lease and the possessory rights of any Persons claiming
through or under such assignee or by virtue of any statute or of any order of
any court, (ii) such new lease shall require all defaults existing under this
Lease to be cured by Tenant named herein with due diligence (other than any
bankruptcy default of a prior tenant), and (iii) such new lease shall require
Tenant named herein to pay all Rent which, had this Lease not been so
disaffirmed, rejected or terminated, would have become due under the provisions
of this Lease after the date of such disaffirmance, rejection or termination
with respect to any period prior thereto. If Tenant named herein defaults in its
obligation to enter into such new lease for a period of thirty (30) days after
Landlord's request, then, in addition to all other rights and remedies by reason
of default, either at law or in equity, Landlord shall have the same rights and
remedies against Tenant named herein as if it had entered into such new lease
and such new lease had thereafter been terminated as of the commencement date
thereof by reason of Tenant's default thereunder.

     Section 15.14 Pledge or Encumbrance. Notwithstanding any other provision of
                   ---------------------
this Lease to the contrary, Tenant shall not pledge or encumber its interest
under this Lease, nor shall Tenant permit any pledge or encumbrance by any
assignee or subtenant, without Landlord's express prior written consent, which
may be withheld in Landlord's sole and absolute discretion.

     Section 15.15 Business Partners. Notwithstanding any of the foregoing to
                   -----------------
the contrary, Tenant shall have the right, without being subject to any consent
or profit rights of Landlord, to permit the use of non-material portions of the
Premises for the Permitted Use by Persons who are clients, joint venturers,
business partners, research partners, contractors and similar business invitees
or associates. Tenant shall not

                                      -54-

<PAGE>

intentionally utilize the rights granted to Tenant pursuant to this Section
15.15 for the purpose of avoiding Landlord's right to share in profits pursuant
to Section 15.6.

                                   ARTICLE 16
                                     ACCESS
                                     ------

     Tenant shall permit Landlord, Landlord's agents and public utility service
providers servicing the Building to erect, use and maintain concealed ducts,
pipes and conduits in and through the Premises provided such use does not cause
the usable area of the Building to be reduced beyond a de minimis amount and
does not unreasonably interfere with Tenant's use and enjoyment of the Premises.
Landlord shall promptly repair any damage to the Building or Tenant's Property
caused by any work performed pursuant to this Article 16. Landlord, any
                                              ----------
Mortgagee, any Lessor, Landlord's Agent and any contractor or subcontractor of
any of the foregoing, and their respective agents shall have the right to enter
the Building at all reasonable times, upon reasonable notice (which notice may
be oral but must be actually given to the party designated by Tenant and located
in Woodland Park to receive such notice) except in the case of emergency (in
which case no such notice shall be required), to examine the Building, to show
the Building to prospective purchasers, Mortgagees or Lessors of the Building
and their respective agents and representatives, to make such repairs,
alterations or additions to the Building or perform its required services under
Article 11 (i) as Landlord may deem necessary or appropriate to fulfill its
----------
obligations under this Lease, (ii) which Landlord may elect to perform following
Tenant's failure to perform, or (iii) to comply with any Requirements, and
Landlord shall be allowed to take all material into the Building that may be
required for the performance of such work without the same constituting an
actual or constructive eviction of Tenant in whole or in part and without any
abatement of Rent. Notwithstanding the foregoing, (i) Tenant shall have the
right under this Lease to install security systems and equipment in, around and
on top of any structure within the Premises, subject to Landlord's and the
Association's reasonable approval, and to have locked rooms and secured areas,
and no access shall be permitted to areas of the Premises designated as secure
by Tenant unless Landlord or such other parties shall be accompanied by
designated personnel of Tenant and (ii) such access, if for the purpose of
repairs, alterations or additions to the Building, shall, at Tenant's request
and at Tenant's expense, be solely after normal business hours.

                                   ARTICLE 17
                                     DEFAULT
                                     -------

     Section 17.1 Tenant's Defaults. Each of the following events shall be an
                  -----------------
"Event of Default" hereunder:

                  (a)   Tenant fails to pay when due any installment of Rent and
such default shall continue for five (5) Business Days after notice of such
default is given to Tenant; provided, however, that for those items of Rent
which are not paid

                                      -55-

<PAGE>

routinely on a monthly basis, it shall not be an Event of Default until the
default in payment thereof shall continue for ten (10) Business Days after
notice of default is given to Tenant, except that if Landlord shall have given
two (2) such notices of default in the payment of any Rent in any twelve (12)
month period, in addition to all other rights and remedies hereunder, Landlord
shall be entitled to a late charge (which Landlord shall waive such late charge
the first two times in any twelve (12) month period that Tenant fails to make
any installment or other payment of Rent when due) equal to five percent (5%) of
any Rent payment which is not paid within five (5) Business Days after its due
date until such time as twelve (12) consecutive months shall have lapsed without
Tenant having failed to make any such payment when due; or

                  (b)   Tenant fails to observe or perform any other term,
covenant or condition of this Lease to be observed or performed by Tenant and if
such failure continues for more than thirty (30) days after notice by Landlord
to Tenant of such default, or if such default is of such a nature that it cannot
be completely remedied within thirty (30) days, failure by Tenant to commence to
remedy such failure within said thirty (30) days, and thereafter diligently
prosecute to completion all steps necessary to remedy such default; or

                  (c)   Tenant's interest in this Lease shall devolve upon or
pass to any Person, whether by operation of law or otherwise, except as
expressly permitted under Article 15 hereof; or
                          ----------

                  (d)   Tenant is unable to, or admits in writing its inability
to, pay its debts as they become due; or

                  (e)   Tenant files a voluntary petition in bankruptcy or
insolvency, or is adjudicated a bankrupt or insolvent, or files any petition or
answer seeking any reorganization, liquidation, dissolution or similar relief
under any present or future federal bankruptcy act or any other present or
future applicable federal, state or other statute or law, or makes an assignment
for the benefit of creditors or seeks or consents to or acquiesces in the
appointment of any trustee, receiver, liquidator or other similar official for
Tenant or for all or any substantial part of Tenant's property; or

                  (f)   if, within one hundred twenty (120) days after the
commencement of any proceeding against Tenant, whether by the filing of a
petition or otherwise, seeking bankruptcy, insolvency, reorganization,
arrangement, composition, readjustment, liquidation, dissolution or similar
relief under the present or any future federal bankruptcy act or any other
present or future applicable federal, state or other statute or law, such
proceeding shall not have been dismissed, or if, within one hundred twenty (120)
days after the appointment of any trustee, receiver, liquidator or other similar
official for Tenant or for all or any substantial part of Tenant's property,
without the consent or acquiescence of Tenant, as the case may be, such
appointment shall not have been vacated or otherwise discharged, or if any lien,
execution or attachment or other similar filing shall be made or issued against
Tenant or any of property pursuant to which the Premises shall be taken or
occupied by someone other than Tenant.

                                      -56-

<PAGE>

         Upon the occurrence of any one or more of such Events of Default,
Landlord may, at its sole option, give to Tenant five (5) days notice of
cancellation of this Lease, in which event this Lease and the Term shall come to
an end and expire (whether or not the Term shall have commenced) upon the
expiration of such five (5) day period with the same force and effect as if the
date set forth in the notice was the Expiration Date stated herein; and Tenant
shall then quit and surrender the Premises to Landlord, but Tenant shall remain
liable for damages as provided in Article 18 hereof.
                                  ----------

         Landlord shall use reasonable efforts to relet the Premises and to
mitigate damages; provided, however, that Tenant understands and agrees that
Landlord's main priority will be the leasing of other space in Woodland Park
controlled by Landlord or any Landlord Affiliate (and not then leased by
Landlord or such Landlord Affiliate), and the reletting of the Premises will be
of lower priority and that Landlord shall have the right to reject tenants based
on any factor at all or for any reason at all, the right to market or package
the space in any configuration, and no liability for failure to relet or
mitigate (so long as Landlord undertakes reasonable efforts as aforesaid).

         Section 17.2 Tenant's Liability. If, at any time, (a) Tenant shall be
                      ------------------
comprised of two or more Persons, (b) Tenant's obligations under this Lease
shall have been guaranteed by any Person other than Tenant, or (c) Tenant's
interest in this Lease shall have been assigned, then, except as otherwise
provided in this Lease, the word "Tenant," as used in Section 17.1 (d), (e) and
(f), shall be deemed to mean any one or more of the Persons primarily or
secondarily liable for Tenant's obligations under this Lease. Any monies
received by Landlord from or on behalf of Tenant during the pendency of any
proceeding of the types referred to in this Article 17 shall be deemed paid as
                                            ----------
compensation for the use and occupancy of the Premises and the acceptance of any
such compensation by Landlord shall not be deemed an acceptance of Rent or a
waiver on the part of Landlord of any rights under this Lease.

                                   ARTICLE 18
                              REMEDIES AND DAMAGES
                              --------------------

         Section 18.1 (a) Remedies. If any Event of Default shall continue, and
                          --------
this Lease and the Term terminates as provided in Article 17:
                                                  ----------

                          (i)   Surrender of Possession. Upon such termination,
                                -----------------------
Tenant shall quit and surrender the Premises to Landlord, and Landlord and its
agents may immediately, or at any time after such Event of Default, re-enter the
Premises or any part thereof, without notice, either by summary proceedings, or
by any other applicable action or proceeding, or otherwise in accordance with
applicable legal proceedings (without being liable to indictment, prosecution or
damages therefor), and may repossess the Premises and dispossess Tenant and any
other Persons from the Premises and remove any and all of their property and
effects from the Premises.

                          (ii)  Landlord's Reletting. Landlord, at Landlord's
                                --------------------
option, may relet all or any part of the Premises from time to time, either in
the name of

                                      -57-

<PAGE>

Landlord or otherwise, to such tenant or tenants, for any term ending before, on
or after the Expiration Date, at such rental and upon such other conditions
(which may include concessions and free rent periods as Landlord may determine
to be necessary or appropriate in light of market conditions) as Landlord, in
its discretion, may determine. Subject to Landlord's obligations described in
Section 17.1(f) hereof, Landlord shall not be liable for failure to relet or, in
the event of any such reletting, for failure to collect any rent due upon any
such reletting; and no such refusal or failure shall relieve Tenant of, or
otherwise affect, any liability under this Lease. Landlord, at Landlord's
option, may make such alterations, decorations and other physical changes in and
to the Premises as Landlord, in its sole discretion, considers advisable or
necessary in connection with such reletting or proposed reletting, without
relieving Tenant of any liability under this Lease or otherwise affecting any
such liability.

                      (b) Tenant's Waiver.  Tenant, on its own behalf and on
                          ---------------
behalf of all Persons claiming through or under Tenant, including all creditors,
hereby waives all rights which Tenant and all such Persons might otherwise have
under any Requirement (i) to the service of any notice of intention to re-enter
or to institute legal proceedings, (ii) to redeem, or to re-enter or repossess,
the Premises, or (iii) to restore the operation of this Lease, after (A) Tenant
shall have been dispossessed by final judgment or by final warrant of any court
or judge (i.e., after exhaustion of all appeals, Tenant's failure to appeal or
the expiration of any applicable appeal periods), (B) any re-entry by Landlord
in accordance with clause (i) above, or (C) any expiration or early termination
of the Term in accordance with the terms hereof, whether such dispossession,
re-entry, expiration or termination shall be by operation of law or pursuant to
the provisions of this Lease. The words "re-enter," "re-entry" and "re-entered"
as used in this Lease shall not be deemed to be restricted to their technical
legal meanings.

                      (c) Tenant's Breach. Upon the breach by Tenant of any
                          ---------------
term, covenant or condition of this Lease, Landlord shall have the right to
enjoin such breach and to invoke any other remedy allowed by law or in equity as
if re-entry, summary proceedings and other special remedies were not provided in
this Lease for such breach.

                      (d) Landlord's Breach. Upon the breach by Landlord of any
                          -----------------
term, covenant or condition of this Lease, Tenant shall have the right to enjoin
such breach and to invoke any other remedy allowed by law or in equity, except
as expressly set forth to the contrary herein.

                      (e) Cumulative Remedies. Except as expressly set forth
                          -------------------
herein to the contrary, the rights to invoke the remedies set forth in this
Lease for either Landlord or Tenant are cumulative and shall not preclude either
party from invoking any other remedy allowed at law or in equity.

         Section 18.2 (a) Damages. If this Lease and the Term expire and come to
                          -------
an end as provided in Article 17, or by or under any summary proceeding or any
                      ----------
other action or proceeding, or if Landlord shall re-enter the Premises as
provided in Section 18.1, then, in any of such events:

                                      -58-

<PAGE>

                          (i)    Tenant shall pay to Landlord all Fixed Rent,
all sums payable pursuant to Article 8 of this Lease (including Tenant's Tax
                             ---------
Payment and Tenant's Operating Expense Payment) and all other items of Rent
payable under this Lease by Tenant to Landlord up to the Expiration Date or to
the date of re-entry upon the Premises by Landlord, as the case may be;

                          (ii)   Landlord shall be entitled to retain all
monies, if any, paid by Tenant to Landlord, whether as prepaid Rent or
otherwise, which monies, to the extent not otherwise applied to amounts due and
owing to Landlord, shall be credited by Landlord against any damages payable by
Tenant to Landlord, with the balance, if any, to be paid to Tenant;

                          (iii)  Tenant shall pay to Landlord, in monthly
installments, on the days specified in this Lease for payment of installments of
Fixed Rent, any Deficiency; it being understood that Landlord shall be entitled
to recover the Deficiency from Tenant each month as the same shall arise, and no
suit to collect the amount of the Deficiency for any month shall prejudice
Landlord's right to collect the Deficiency for any subsequent month by a similar
proceeding; and

                          (iv)   whether or not Landlord shall have collected
any monthly Deficiency, Tenant shall pay to Landlord, on demand, in lieu of any
further Deficiency and as liquidated and agreed final damages, a sum equal to
the amount by which the Rent for the period which otherwise would have
constituted the unexpired portion of the Term (assuming the Additional Rent
during such period to be the same as was payable for the year immediately
preceding such termination or re-entry), less the aggregate amount of
Deficiencies theretofore collected by Landlord pursuant to the provisions of
Section 18.2(a)(iii) for the same period, less the fair market value of the
unexpired portion of such term taking into account all relevant factors, all
discounted to present value at a discount rate equal to the then-effective
interest rate per annum for Treasury securities maturing closest to the stated
Expiration Date. If the Premises, or any part thereof, shall have been relet by
Landlord for the period which otherwise would have constituted the unexpired
portion of the Term, or any part thereof, the amount of rent reserved upon such
reletting, less any amounts paid or incurred by Landlord (including but not
limited to commissions, and any tenant concessions) to secure such reletting,
shall be deducted from the amount payable to Landlord pursuant to the preceding
sentence in lieu of fair market value rent specified above.

                     (b)  Reletting. Tenant shall not be entitled to any rents
                          ---------
collected or payable under any reletting, whether or not such rents exceed the
Fixed Rent reserved in this Lease. Nothing contained in Articles 17 or 18 shall
                                                        -----------    --
be deemed to limit or preclude the recovery by Landlord from Tenant of the
maximum amount allowed to be obtained as damages by any Requirement, or of any
sums or damages to which Landlord may be entitled in addition to the damages set
forth in this Section 18.2.

                     (c)  No Consequentials. In no event shall either party be
                          -----------------
liable for any consequential, indirect, or punitive damages in connection with
this Lease.

                                      -59-

<PAGE>

         Section 18.3  Default Interest; Other Rights of Landlord. Any Rent, sum
                       ------------------------------------------
of money or damages payable under this Lease by either Landlord or Tenant and
not paid when due shall bear interest at the Interest Rate from the due date
until paid, and, in the case of Tenant's default, the interest shall be deemed
Additional Rent. If Tenant fails to pay any Additional Rent when due, Landlord,
in addition to any other right or remedy, shall have the same rights and
remedies as in the case of a default by Tenant in the payment of Fixed Rent. If
Tenant is in arrears in the payment of Rent, Tenant waives Tenant's right, if
any, to designate the items against which any payments made by Tenant are to be
credited, and Landlord may apply any payments made by Tenant to any items
Landlord sees fit, regardless of any request by Tenant.

                                   ARTICLE 19
                        RIGHT TO CURE; FEES AND EXPENSES
                        --------------------------------

         Section 19.1  Tenant's Default. If Tenant defaults in the performance
                       ----------------
of any obligation under this Lease, Landlord, without thereby waiving such
default, and subject to all other applicable provisions of this Lease, including
Section 7.3 hereof, may perform such obligation for the account and at the
expense of Tenant: (a) immediately or at any time thereafter, and without notice
(as long as Tenant is not diligently engaged in curing such default), in the
case of emergency or in the case the default (i) will result in a violation of
any material Requirement, or (ii) will result in a cancellation of any insurance
policy maintained by Landlord, and (b) in any other case if such default
continues after thirty (30) days (or the applicable cure period, if shorter)
from the date Landlord gives notice of Landlord's intention so to perform the
defaulted obligation. All costs and expenses reasonably incurred by Landlord in
connection with any such performance by it for the account of Tenant and all
reasonable costs and expenses, including reasonable counsel fees and
disbursements, incurred by Landlord in any action or proceeding (including any
summary dispossession proceeding) brought by Landlord to enforce any obligation
of Tenant under this Lease and/or right of Landlord in or to the Premises, shall
be paid by Tenant to Landlord within thirty (30) days of demand, with interest
thereon at the Interest Rate from the date incurred by Landlord. Except as
expressly provided to the contrary in this Lease, all costs and expenses which,
pursuant to this Lease (including the Rules and Regulations) are incurred by
Landlord and payable to Landlord by Tenant, and all charges, amounts and sums
payable to Landlord by Tenant for any property, material, labor, utility or
other services which, pursuant to this Lease or at the request and for the
account of Tenant, are provided, furnished or rendered by Landlord, shall become
due and payable by Tenant to Landlord thirty (30) days after demand therefor.

         Section 19.2  Landlord's Default.
                       ------------------

                       (a)  If Landlord defaults in the performance of any
obligation under this Lease (other than any de minimis obligation) Tenant,
without thereby waiving such default, and subject to all other applicable
provisions of this Lease, including Section 7.3 hereof, may perform such
obligation for the account and, to the extent not otherwise properly includible
as an Operating Expense, at the expense of Landlord if

                                      -60-

<PAGE>

such default continues after thirty (30) days (or the applicable cure period, if
shorter) from the date Tenant gives notice of Tenant's intention so to perform
the defaulted obligation. All costs and expenses reasonably incurred by Tenant
in connection with any such performance by it for the account of Landlord and
all reasonable costs and expenses, including reasonable counsel fees and
disbursements, incurred by Tenant in any action or proceeding brought by Tenant
to enforce any obligation of Landlord under this Lease and/or right of Tenant in
or to the Premises, shall be paid by Landlord to Tenant within thirty (30) days
of final, non-appealable judicial or arbitration determination that Landlord was
in default, with interest thereon at the Interest Rate from the date incurred by
Tenant.

                     (b)  If Landlord fails to timely pay to Tenant any sum to
which Tenant is entitled under this Lease on account of any Landlord default
(after notice and cure), then Tenant may offset the amount owed by Landlord to
Tenant from the next payments of Rent as follows: (i) if Landlord fails to make
any payment of Real Estate Taxes required to be made by Landlord under this
Lease prior to delinquency (other than as a result of Tenant's failure to make
the reimbursement Tenant is required to make), and such failure continues for a
period of thirty (30) days after written notice thereof from Tenant to Landlord,
Tenant shall have the right, but not the obligation, to pay such Real Estate
Taxes on behalf of Landlord, and to deduct the amount so paid (plus interest
from the date paid to the date recovered at the Default Rate) from the next
payments of Rent required to be paid by Tenant hereunder, until such amount has
been recovered in full; (ii) if the amounts owed to Tenant are on account of any
unpaid portion of Landlord's Contribution or Supplemental Allowance, and/or any
reimbursement to Broker for Tenant made by Tenant on account of Landlord's
failure to pay Broker for Tenant its commission when due under the terms of a
separate agreement between Landlord and Broker for Tenant, then no limits on
offset shall apply; and (iii) if Tenant obtains a final, non-appealable judgment
against Landlord pursuant to Section 19.2(a) above, Tenant shall have the right,
in addition to the execution upon Landlord as and to the extent permitted under
Section 19, to offset the amount of such judgment in full against the next
payments of Rent payable by Tenant hereunder (with a final arbitration award
made pursuant to Section 34 of this Lease being deemed to constitute a final,
non-appealable judgment). The amounts set forth in clauses (i)-(iii) above are
sometimes known as the "Special Offset Amounts".

                     (c)  The parties agree that any dispute regarding the
propriety of Tenant's exercise of self-help rights granted to it hereunder,
and/or regarding the propriety of Tenant's exercise of offset rights granted to
it hereunder, shall be subject to arbitration pursuant to Section 34 of this
Lease, provided Landlord's election to arbitrate a dispute regarding the
propriety of Tenant's exercise of a aright of self-help or offset under Section
19.2 of this Lease shall be limited to the determination of whether Tenant's
action(s) were or were not exercised in violation of the terms of this Lease,
and shall not vitiate such right before the fact.

                                       -61-

<PAGE>

                                   ARTICLE 20
                LANDLORD REPRESENTATIONS AND COVENANTS; APPROVALS
                -------------------------------------------------

         Section 20.1   Representations. Except as expressly set forth in this
                        ---------------
Lease, Landlord and Landlord's agents have made no warranties, representations,
statements or promises with respect to the Premises and no rights, easements or
licenses are acquired by Tenant by implication or otherwise. This Lease contains
the entire agreement between the parties and all understandings and agreements
previously made between Landlord and Tenant are merged in this Lease, which
alone fully and completely expresses their agreement with respect to the lease
of the Premises by Tenant. Tenant is entering into this Lease after full
investigation and is not relying upon any statement or representation made by
Landlord not embodied in this Lease.

         Section 20.2   Proffers and Development Conditions. Landlord shall
                        -----------------------------------
comply with all of the requirements, obligations and responsibilities (including
the timing associated with such requirements, obligations and responsibilities)
of the proffers/development conditions associated with RZ 1999-HM-037, I and III
and dated September 8, 2000, as may be amended from time to time ("Proffers")
and the Development Conditions associated with Special Exception Amendment
97-H-070-2, approved by the Fairfax County Board of Supervisors on September 11,
2000 ("Development Conditions"), but solely to the extent such Proffers and
Development Conditions relate to the Premises or the development or occupancy of
the Premises by Tenant, including without limitation, those certain Proffers and
Development Conditions that do not have definite timing associated with the
requirement to satisfy such Proffers and Development Conditions which are set
forth on Exhibit X attached hereto. Landlord agrees that Landlord shall satisfy
         ---------
the Proffers and Development Conditions set forth on Exhibit X in accordance
                                                     ---------
with the timing set forth on such Exhibit. Landlord shall not agree to any new
Proffers or Development Conditions or amendments to existing Proffers or
Development Conditions which would have the effect of decreasing Tenant's rights
or increasing Tenant's obligations hereunder (other in a de minimis manner)
without the prior written approval of Tenant, not to be withheld in bad faith or
unreasonably withheld, conditioned or delayed.

         Section 20.3   Actions Pending. As of the date hereof, there is no
                        ---------------
litigation or condemnation actions pending, or to Landlord's knowledge,
threatened against Landlord or the Project, other than those that are of the
routine "slip and fall" type covered by Landlord's insurance.

         Section 20.4   Future Development. With regard to the development of
                        ------------------
Waterview, so long as Tenant is leasing 100% of the Agreed Area of the Building,
Landlord shall provide Tenant with reasonable approval rights regarding the
initial and ongoing development and operation of amenities in the Building. With
respect to the remainder of Waterview, Landlord shall provide (and shall cause
Landlord's Affiliates to provide) Tenant with periodic status reports and
meaningful opportunities for input and consultation regarding the initial and
ongoing development and operation of amenities,

                                      -62-

<PAGE>

and Landlord covenants to consider in good faith and accommodate where
reasonably possible, Tenant's reasonable suggestions.

         Section 20.5  Encumbrances. Notwithstanding anything in this Lease to
                       ------------
the contrary, Landlord shall not execute any easements, covenants, conditions,
encumbrances, restrictions or other title matters which would encumber the
Premises, nor seek any change to the Approved Zoning or other governmental
approval with respect to the Premises, which would prevent or impair the ability
of Landlord to complete the Base Building Work or Tenant to complete the Initial
Installations, or would prevent or impair the ability of Tenant from using or
operating the Premises in the ordinary course of its business or would otherwise
adversely affect Tenant in more than a de minimis manner, without first
obtaining Tenant's prior written consent in each instance, which consent shall
not be unreasonably withheld, conditioned or delayed. If Tenant fails to respond
within eleven (11) Business Days after written notice from Landlord requesting
Tenant's consent (which request includes a proposed form of the easement in
question and states in a conspicuous fashion that the failure to respond within
eleven (11) Business Days after receipt or deemed receipt will constitute
consent to the item in question), Tenant shall be deemed to have consented. Any
dispute regarding consent under this Section 20.5 shall be subject to
arbitration hereunder. Landlord hereby represents that as of the date hereof, to
Landlord's knowledge there are no unrecorded agreements with third parties
encumbering any portion of the Property.

         Section 20.6  Government Incentives. In the event Landlord receives any
                       ---------------------
Incentives from any federal, state or local government on behalf of Tenant or on
account of Tenant's occupancy in Waterview, Landlord agrees to convey the full
amount of the Incentive received by Landlord to Tenant either (i) as a credit
against Rent, or (ii) in the form of a reimbursement check to be delivered by
Landlord to Tenant within five (5) Business Days after Landlord receives such
Incentive. "Incentives" shall mean any Tenant-initiated tangible incentives that
are paid to Landlord in the form of (a) cash, or (b) cash equivalents. To the
extent an Incentive is received in a non-cash or non-cash equivalent form,
Landlord and Tenant will work together cooperatively to equitably allocate such
Incentive.

         Section 20.7  Restaurants and Retailers. Landlord shall use good faith
                       -------------------------
and diligent efforts to offer as part of the development of Waterview II and
Waterview III upscale restaurants and ancillary amenity retail businesses
consistent with a first class office/retail development such as a bank, deli,
concierge, dry cleaner (pick up only), and exercise facility all located within
the initial and subsequent buildings that will be constructed at Waterview. With
respect to First Class Retailers (as defined below), Landlord shall consult with
and provide Tenant with meaningful input concerning the leasing of such space to
such tenants. With respect to retailers not meeting the criteria of First Class
Retailers, Tenant shall have reasonable approval rights over such tenants.
"First Class Retailers" shall mean retailers of a quality and nature similar to
those at Reston Town Center at the time.

                                       -63-

<PAGE>

         Section 20.8   Written Approval. All references in this Lease to the
                        ----------------
consent or approval of Landlord or Tenant mean the written consent or approval
of Landlord or Tenant, as the case may be, unless otherwise specifically
provided.

         Section 20.9   No Money Damages. Wherever in this Lease Landlord's
                        ----------------
consent or approval is required, if Landlord refuses to grant such consent or
approval, whether or not Landlord expressly agreed that such consent or approval
would not be unreasonably withheld, Tenant shall not make, and Tenant hereby
waives, any claim for money damages (including any claim by way of set-off,
counterclaim or defense) based upon Tenant's claim or assertion that Landlord
unreasonably withheld or delayed its consent or approval. Tenant's sole remedy
shall be an action or proceeding to enforce such provision, by specific
performance, injunction or declaratory judgment. Notwithstanding the foregoing,
Tenant may seek and, if Tenant prevails, recover, actual damages (and not
                                                                      ---
consequential or punitive damages of any sort) only if in withholding, delaying
                                               ----
or conditioning such consent, or in being silent, Landlord is found to have
acted in bad faith or in an arbitrary and capricious manner. Wherever Landlord
agrees in this Lease not to unreasonably withhold its approval or consent,
Landlord agrees that such approval or consent shall also not be unreasonably
delayed or conditioned. In addition, if Landlord's consent or approval is
requested by Tenant, then: (a) if (i) a time period is specified in this Lease
for Landlord to respond, such time period shall govern, and (ii) no time period
is so specified, the time period shall be deemed to be eleven (11) Business Days
(so long as the request includes a statement in a conspicuous fashion that the
failure to respond within eleven (11) Business Days after receipt or deemed
receipt will constitute consent to the item in question); and (b) if Landlord
fails to respond within the specified (or deemed) time period, then Landlord
shall be deemed to have consented to the item in question.

                                   ARTICLE 21
                                   END OF TERM
                                   -----------

         Section 21.1   Expiration. Upon the expiration or other termination of
                        ----------
this Lease, Tenant shall quit and surrender the Premises to Landlord vacant,
broom clean and in good order and condition, ordinary wear and tear and damage
for which Tenant is not responsible under the terms of this Lease excepted, and
Tenant shall remove all of Tenant's Property, and the Initial Installations and
Tenant's Alterations to the extent required pursuant to Article 5 of this Lease.
                                                        ---------
The foregoing obligation shall survive the expiration or sooner termination of
the Term.

         Section 21.2   Holdover Rent. Landlord and Tenant recognize that the
                        -------------
damage to Landlord resulting from any failure by Tenant to timely surrender
possession of the Premises may be substantial, may exceed the amount of the Rent
theretofore payable hereunder, and will be impossible to accurately measure.
Tenant therefore agrees that if possession of the Premises is not surrendered to
Landlord within twenty-four (24) hours after the Expiration Date or sooner
termination of the Term, in addition to any other rights or remedies Landlord
may have hereunder or at law, Tenant shall pay to Landlord for each month
(pro-rated, if applicable, on a daily basis) during which Tenant

                                      -64-

<PAGE>

holds over in the Premises after the Expiration Date or sooner termination of
the Term, a sum equal to: the greater of Landlord's reasonable estimate of the
current fair market value rent or one hundred twenty-five percent (125%) of the
monthly Rent payable under this Lease for the last full calendar month of the
Term for each of the first two (2) months of such holdover; one hundred fifty
percent (150%) of the greater of Landlord's reasonable estimate of the current
fair market value rent or the monthly Rent payable under this Lease for the last
full calendar month of the Term for each of the next two (2) months; and two
hundred percent (200%) of the greater of Landlord's reasonable estimate of the
current fair market value or the monthly Rent payable under this Lease for the
last full calendar month of the Term for each holdover month thereafter
(determined on a phase by phase basis). No holding-over by Tenant, nor the
payment to Landlord of the amounts specified above, shall operate to extend the
Term hereof. Nothing herein contained shall be deemed to permit Tenant to retain
possession of the Premises after the Expiration Date or sooner termination of
this Lease, and no acceptance by Landlord of payments from Tenant after the
Expiration Date or sooner termination of the Term shall be deemed to be other
than on account of the amount to be paid by Tenant in accordance with the
provisions of this Article 21. All of Tenant's obligations under this Article 21
                   ----------                                         ----------
shall survive the expiration or earlier termination of the Term of this Lease.

     Section 21.3 Short Term Surrender Option. In order to accommodate Tenant's
                  ---------------------------
ability to time its surrender of the Premises consistent with then-existing
circumstances (as of the expiration of the Term of this Lease), Landlord agrees
that Tenant shall have a one-time right and option (the "Surrender Option") to
extend the Term as to not less than 50% of the Agreed Area of the Building for a
fixed term of six (6) months, which additional period (the "Surrender Term")
shall constitute a part of the Term of this Lease. Tenant shall exercise its
Surrender Option by written notice to Landlord delivered not less than eighteen
(18) months prior to the expiration of the Term then ending (which the parties
agree may include any Extension Period). In the event that Tenant fails or
declines to provide the applicable written notice exercising the Surrender
Option (subject, however, to Tenant's right to provide a Renewal Notice pursuant
to Section 51, if a Renewal Option is then still available for exercise by
Tenant) prior to the expiration of the time period described in the preceding
sentence, then the Surrender Option, and all unexercised Renewal Options, shall,
upon the expiration of such time period, become null and void and be of no
further force or effect. If Tenant exercises the Surrender Option, the same
shall be irrevocable and shall constitute Tenant's irrevocable waiver of all
unexercised Extension Options under this Lease, if any. The Surrender Term shall
be upon the same terms and conditions applicable to the Floor(s) as of the last
day of the Lease Year then ending, except that the monthly Rent payable for such
period shall equal one hundred three and one-half percent (103.5%) of the
monthly Rent payable under this Lease for the last full calendar month of the
Term prior to the Surrender Term, in accordance with the terms of Section
2.3(d). In the event that Tenant leases any space in Waterview II or Waterview
III, Tenant shall have the option to extend the then current Term of this Lease
in accordance with the terms of Section 2.3(d) above.

                                      -65-

<PAGE>

                                   ARTICLE 22
                                 QUIET ENJOYMENT
                                 ---------------

     Provided this Lease is in full force and effect and no Event of Default
then exists, Tenant may peaceably and quietly enjoy the Premises without
hindrance by Landlord or any Person lawfully claiming through or under Landlord,
subject to the terms and conditions of this Lease.

                                   ARTICLE 23
                             NO SURRENDER; NO WAIVER
                             -----------------------

     Section 23.1 No Surrender or Release. No act or thing done by Landlord or
                  -----------------------
Landlord's agents or employees during the Term shall be deemed an acceptance of
a surrender of the Premises, and no provision of this Lease shall be deemed to
have been waived by either Landlord or Tenant, unless such waiver is in writing
and is signed by Landlord or Tenant, as the case may be, and any such waiver
shall be effective only for the specific purpose and in the specific instance in
which given. If Tenant at any time desires to have Landlord sublet the Premises
for Tenant's account, Landlord or Landlord's agents are authorized to receive
Tenant's keys to the Premises for such purpose without releasing Tenant from any
of the obligations under this Lease, and Tenant hereby relieves Landlord of any
liability for loss of or damage to any of Tenant's effects in connection with
such subletting.

     Section 23.2 No Waiver. The failure of either party to seek redress for
                  ---------
violation of, or to insist upon the strict performance of, any covenant or
condition of this Lease, or any of the Rules and Regulations, shall not be
construed as a waiver or relinquishment for the future performance of such
obligations of this Lease or the Rules and Regulations, or of the right to
exercise such election but the same shall continue and remain in full force and
effect with respect to any subsequent breach, act or omission. The receipt by
Landlord of any Rent payable pursuant to this Lease or the receipt by either
party of any other sums due from the other party with knowledge of the breach of
any covenant of this Lease shall not be deemed a waiver of such breach. No
payment by Tenant or receipt by Landlord of a lesser amount than the monthly
Fixed Rent or Additional Rent herein stipulated shall be deemed to be other than
a payment on account of the earliest stipulated Fixed Rent or Additional Rent,
or as Landlord may elect to apply such payment, nor shall any endorsement or
statement on any check or any letter accompanying any check or payment as Fixed
Rent or Additional Rent be deemed an accord and satisfaction, and Landlord may
accept such check or payment without prejudice to Landlord's right to recover
the balance of such Fixed Rent or Additional Rent or pursue any other remedy
provided in this Lease. The existence of a right of renewal or extension of this
Lease, or the exercise of such right, shall not limit Landlord's right to
terminate this Lease in accordance with the terms hereof, or create any option
for further extension or renewal of this Lease.

                                      -66-

<PAGE>

                                   ARTICLE 24
                             WAIVER OF TRIAL BY JURY
                             -----------------------

     LANDLORD AND TENANT HEREBY WAIVE TRIAL BY JURY IN ANY ACTION, PROCEEDING OR
COUNTERCLAIM BROUGHT BY EITHER PARTY AGAINST THE OTHER ON ANY MATTERS IN ANY WAY
ARISING OUT OF OR CONNECTED WITH THIS LEASE, THE RELATIONSHIP OF LANDLORD AND
TENANT, TENANT'S USE OR OCCUPANCY OF THE PREMISES, OR THE ENFORCEMENT OF ANY
REMEDY UNDER ANY STATUTE, EMERGENCY OR OTHERWISE. If Landlord commences any
summary proceeding against Tenant, Tenant will not interpose any non-mandatory
counterclaim of any nature or description in any such proceeding (unless failure
to impose such counterclaim would preclude Tenant from asserting in a separate
action the claim which is the subject of such counterclaim), and will not seek
to consolidate such proceeding with any other action which may have been or will
be brought in any other court by Tenant.

                                   ARTICLE 25
                              INABILITY TO PERFORM
                              --------------------

     Subject to the provisions of this Lease, and the obligation of Tenant to
pay Rent and to perform all of the other covenants and agreements of Tenant
hereunder shall not be affected, impaired or excused by any Unavoidable Delays.
Landlord shall use reasonable efforts to (i) promptly notify Tenant of any
Unavoidable Delay which prevents Landlord from fulfilling any of its obligations
under this Lease and (ii) overcome any obstacles causing such Unavoidable Delay.
The foregoing provision shall not apply to Unavoidable Delays which affect
Landlord's or Tenant's obligations to complete the Base Building Work and/or the
Initial Installations, which shall be governed by the specific terms of this
Lease and the Design and Construction Agreement relating thereto.

                                   ARTICLE 26
                                     NOTICES
                                     -------

     Except as otherwise expressly provided in this Lease, all consents,
notices, demands, requests, designations, approvals and other communications
under this Lease shall be in writing and shall be deemed sufficiently given or
rendered if delivered by hand (provided a signed receipt is obtained) or if sent
by registered or certified mail (return receipt requested) or by a nationally
recognized overnight delivery service making receipted deliveries or by
facsimile transmission, provided that any notice given by facsimile transmission
shall also be delivered using one of the other permitted methods of delivering
notices under this Section 26, addressed as follows:

        (a) if to Tenant, (i) at Tenant's address set forth on the first page of
this Lease, Attn.: Henry White if mailed prior to Tenant's taking possession of
the Premises,

                                       -67-

<PAGE>

or (ii) at the Building, Attn: Henry White if mailed subsequent to Tenant's
taking possession of the Premises, with copies to: VeriSign, Inc., 487 E.
Middleton Road, Mountain View, California 94043, Attention: Rick Walsh,
Facsimile: (650) 961-7300; and to VeriSign, Inc., 21355 Ridgetop Circle, Dulles,
Virginia 20166, Attention: Bobby Turnage, Facsimile: (703) 742-7461; and to
Jones Lang LaSalle Americas, Inc., 1400 Business Center Drive, Mount Prospect,
IL 60056, Attention: Mirela Gabrovska, Facsimile: (847) 299-8324; and to Jones
Lang LaSalle Americas, Inc., 8484 Westpark Drive, Suite 710, McLean, Virginia
22102, Attention: A. Jefferson Groh, Facsimile: (703) 269-0246; and, with
respect to default notices only, to Jeffrey R. Keitelman, Esq., Piper Marbury
Rudnick & Wolfe LLP, 1200 Nineteenth Street, N.W., Washington, D.C. 20036-2412,
Facsimile: (202) 223-2085.

          (b) if to Landlord: at Landlord's address set forth on the first
(1/ST/) page of this Lease, Attn.: Regional Director, and with copies to (i)
Tishman Speyer Properties L.P., 520 Madison Avenue, New York, New York 10022,
Attn.: General Counsel, Facsimile: (212) 588-1895, (ii) Hogan & Hartson, L.L.P.,
8300 Greensboro Drive, McLean, Virginia 22102, Attn: Dennis K. Moyer, Esq.,
Facsimile: (703) 610-6200, (iii) Tishman Speyer Properties L.P., 520 Madison
Avenue, New York, New York 10022, Attn: Chief Financial Officer, Facsimile:
(212) 588-1895 and (iv) any Mortgagee or Lessor which shall have requested
copies of notices, by notice given to Tenant in accordance with the provisions
of this Article 26, at the address designated by such Mortgagee or Lessor; or to
        ----------
such other address(es) as either Landlord or Tenant or any Mortgagee or Lessor
may designate as its new address(es) for such purpose by notice given to the
other in accordance with the provisions of this Article 26. Any such approval,
                                                ----------
consent, notice, demand, request or other communication shall be deemed to have
been given on the earlier to occur of the date of receipted delivery or refusal
to accept delivery or three (3) Business Days after it shall have been mailed as
provided in this Article 26.
                 ----------

                                   ARTICLE 27
                              RULES AND REGULATIONS
                              ---------------------

     Tenant shall, and Tenant shall use reasonable efforts to cause Tenant's
contractors, employees, agents, visitors and licensees to observe and comply
with the Rules and Regulations and the Construction Procedures, provided, that
in case of any conflict or inconsistency between the provisions of this Lease
and any of the Rules and Regulations or the Construction Procedures as
originally promulgated or as supplemented or amended from time to time, the
provisions of this Lease shall control. Landlord reserves the right, from time
to time, to adopt additional Rules and Regulations or Construction Procedures
and to amend the Rules and Regulations or Construction Procedures then in
effect; provided, however, that, as to Tenant, any such supplement or amendment
to the Rules and Regulations or Construction Procedures shall (i) be reasonable,
(ii) impose no greater than a de minimis additional cost on Tenant, and (iii)
                              ----------
take effect only after thirty (30) days prior notice to Tenant. Tenant shall
have the right to dispute the reasonableness or effect of any such supplement or
amendment to the Rules and Regulations or the Construction Procedures (or any

                                      -68-

<PAGE>

supplement or amendment thereto) by notice to Landlord given within thirty (30)
days of Tenant's receipt of such supplement or amendment or Construction
Procedures, and, in the event of their failure to agree within ten (10) days
thereafter, either party may submit the same to arbitration in accordance with
Article 34 hereof. Nothing contained in this Lease shall impose upon Landlord
----------
any obligation to enforce the Rules and Regulations or terms, covenants or
conditions in any other lease against any other Building tenant (in the event
that Tenant no longer occupies the entire Building), and Landlord shall not be
liable to Tenant for violation of the same by any other tenant of the Building,
except that Landlord shall not enforce any Rule or Regulation against Tenant in
a discriminatory fashion.

                                   ARTICLE 28
                                     BROKER
                                     ------

          Section 28.1 Broker Representations. Landlord has retained Landlord's
                       ----------------------
Agent as leasing agent in connection with this Lease and Landlord will be solely
responsible for any fee that may be payable to Landlord's Agent. Landlord agrees
to pay a commission to Broker for Tenant pursuant to a separate agreement
between Landlord and Broker for Tenant. Each of Landlord and Tenant represents
and warrants to the other that it has not dealt with any broker in connection
with this Lease other than Landlord's Agent and Broker for Tenant and that to
the best of its knowledge and belief, no other broker, finder or like entity
procured or negotiated this Lease or is entitled to any fee or commission in
connection herewith. The execution and delivery of this Lease by each party
shall be conclusive evidence that each party has relied upon the foregoing
representations and warranties.

          Section 28.2 Indemnity. Each of Landlord and Tenant shall indemnify,
                       ---------
defend, protect and hold the other party harmless from and against any and all
Losses which the indemnified party may incur by reason of any claim of or
liability to any broker, finder or like agent (other than Landlord's Agent and
Broker for Tenant) arising out of the above representation being false. In
addition, Landlord shall indemnify and hold Tenant harmless from and against any
claims by Landlord's Agent or Broker for Tenant for any unpaid commissions. The
provisions of this Article 28 shall survive the expiration or earlier
                   ----------
termination of the Term of this Lease.

                                   ARTICLE 29
                                    INDEMNITY
                                    ---------

          Section 29.1 (a) Tenant's Indemnity. Except for the acts of Landlord
                           ------------------
and those parties claiming by, through or under Landlord, other than Tenant,
Tenant shall not do or permit to be done any act or thing upon the Premises
which would subject Landlord to any liability for injury or damage to persons or
property. Tenant shall indemnify, defend, protect and hold harmless each of the
Indemnitees from and against any and all Losses (as defined in subsection (b)
hereof), resulting from any claims against the Indemnitee related to or arising
from any injury to or death of persons and

                                      -69-

<PAGE>

damage to or theft, misappropriation or loss of property in or about the
Premises, arising from any misconduct, failure to act (when under a duty to do
so) or negligence of (A) Tenant, its contractors, licensees, agents, servants,
employees, invitees or visitors or (B) both Landlord and Tenant, provided,
however, that Tenant's liability hereunder with respect to matters judicially
determined to have arisen in whole or in part out of the misconduct, failure to
act (when under a duty to do so) or negligence of Landlord, as to which
determination all appeals have been exhausted, shall be only to the extent, if
any, that such matters have been so determined to have arisen out of the
misconduct, failure to act (when under a duty to do so) or negligence of Tenant.

               (b) Indemnity Inclusions. The term "Losses" means any and all
                   --------------------
losses, liabilities, damages, claims, judgments, fines, suits, demands, costs,
interest and expenses of any kind or nature (including reasonable attorneys'
fees and disbursements) incurred in connection with any claim, proceeding or
judgment and the defense thereof, and including all costs of repairing any
damage to the Premises.

  Section 29.2 Defense and Settlement. If any claim, action or proceeding is
               ----------------------
made or brought against any Indemnitee, then such Indemnitee shall promptly
notify Tenant and Tenant, at its sole cost and expense, shall resist or defend
such claim, action or proceeding in the Indemnitee's name (if necessary), by
attorneys approved by the Indemnitee, which approval shall not be unreasonably
withheld or delayed. Attorneys for Tenant's insurer shall hereby be deemed
approved for purposes of this Section 29.2. Notwithstanding the foregoing, if
Landlord or any Indemnitee reasonably believes that (i) a conflict of interest
exists which would make it inadvisable to be represented by Tenant's counsel,
(ii) Tenant is not diligently defending the claim, action or proceeding or (iii)
there are legal defenses available to Landlord or any Indemnitee which are
different from or inconsistent with those available to Tenant, Landlord and/or
such Indemnitees shall each be entitled to retain separate counsel and Tenant
shall pay the reasonable fees and expenses of such separate counsel.
Notwithstanding anything herein contained to the contrary, Tenant may direct the
Indemnitee to settle any claim, suit or other proceeding provided that (a) such
settlement shall involve no obligation on the part of the Indemnitee other than
the payment of money, (b) any payments to be made pursuant to such settlement
shall be paid in full exclusively by Tenant at the time such settlement is
reached, (c) such settlement shall not require the Indemnitee to admit any
liability, and (d) the Indemnitee shall have received an unconditional release
from the other parties to such claim, suit or other proceeding (which may be
conditioned upon receiving a reciprocal release from the Indemnitee). The
provisions of this Article 29 shall survive the expiration or earlier
                   ----------
termination of this Lease.

  Section 29.3 Landlord's Indemnity. Except for the acts of Tenant and those
               --------------------
parties claiming by, through or under Tenant, other than Landlord, Landlord
shall not do or permit to be done any act or thing upon the Premises which would
subject Tenant to any liability for injury or damage to persons or property.
Landlord shall indemnify, defend, protect and hold harmless each of the
Indemnitees from and against any and all Losses resulting from any claims
against the Indemnitee related to or arising from any injury to or death of
persons and damage to or theft, misappropriation or loss of

                                      -70-

<PAGE>

property in or about the Premises, arising from any misconduct, failure to act
(when under a duty to do so) or negligence of (A) Landlord, its contractors,
licensees, agents, servants, employees, invitees or visitors or (B) both Tenant
and Landlord, provided, however, that Landlord's liability hereunder with
respect to matters judicially determined to have arisen in whole or in part out
of the misconduct, failure to act (when under a duty to do so) or negligence of
Tenant, as to which determination all appeals have been exhausted, shall be only
to the extent, if any, that such matters have been so determined to have arisen
out of the misconduct, failure to act (when under a duty to do so) or negligence
of Landlord. The indemnity set forth in this Section 29.3 shall be subject to
the same procedures applicable to Tenant's indemnity set forth in Section 29.2,
mutatis mutandis.
------- --------

                                   ARTICLE 30
                         TAX STATUS OF BENEFICIAL OWNERS
                         -------------------------------

     Tenant recognizes and acknowledges that Landlord and/or certain beneficial
owners of Landlord may from time to time qualify as real estate investment
trusts pursuant to Section 856 et seq. of the Code or as entities described in
Section 511(a)(2) of the Code, and that avoiding (a) the loss of such status,
(b) the receipt of any income derived under any provision of this Lease that
does not constitute "rents from real property" (in the case of real estate
investment trusts) or that constitutes "unrelated business taxable income" (in
the case of entities described in Section 511 (a)(2) of the Code), and (c) the
imposition of penalty or similar taxes (each an "Adverse Event") is of material
concern to Landlord and such beneficial owners. In the event that this Lease or
any document contemplated hereby could, in the opinion of counsel to Landlord,
result in or cause an Adverse Event, Tenant agrees to cooperate with Landlord in
negotiating an amendment or modification thereof and shall at the request of
Landlord execute and deliver such documents reasonably required to effect such
amendment or modification, provided that (i) Landlord shall bear the reasonable
cost to Tenant in connection therewith, and (ii) there shall be no increase in
Tenant's obligations or decrease in Tenant's rights (except to a de minimis
extent) as a result thereof. Any amendment or modification pursuant to this
Article 30 shall be structured so that the economic results to Landlord and
----------
Tenant shall be not less favorable (except to a de minimis extent) than those
set forth in this Lease without regard to such amendment or modification.
Without limiting any of Landlord's other rights under this Article 30, Landlord
                                                           ----------
may waive the receipt of any amount payable to Landlord hereunder and such
waiver shall constitute an amendment or modification of this Lease with respect
to such payment.

                                   ARTICLE 31
                                EXTENSION PERIOD
                                ----------------

     Section 31.1 Option to Extend.
                  ----------------

                  (a) Provided Tenant leases and occupies at least fifty percent
(50%) of the Agreed Area of the Building, Tenant shall have the option (the
"Extension

                                      -71-

<PAGE>

Option") to extend the Term of this Lease for three (3) consecutive periods of
five (5) years each (each one, an "Extension Period"). Tenant's right to extend
the Term shall be exercised by giving written notice (the "Option Notice") to
Landlord not later than eighteen (18) months prior to either (i) the original
Expiration Date or (ii) if Tenant exercises its option to extend this Lease for
any Extension Period, the Expiration Date as extended pursuant to this Article
                                                                       -------
31, time being of the essence. If Tenant fails to timely elect to extend the
--
Term, this Lease shall terminate on the applicable Expiration Date, Tenant shall
be deemed to have waived all of its rights under any succeeding Extension
Option, and thereafter the Extension Option shall be null and void and of no
further force or effect.

                      (b) The Extension Option shall be exercised on the
following terms and conditions:

                          (i)  If on the date of the Option Notice or on the
Extension Period commencement date an uncured Material Default shall then exist
by Tenant, Landlord shall have the option to declare Tenant's election to extend
the Term to be null, void and of no force or effect.

                          (ii) This Lease shall not have been terminated.

                      (c) No further rights to extend the Term beyond any
Extension Period described herein shall be created by any extension, except as
mutually agreed to in any documents extending the Term.

                      (d) If Tenant exercises an Extension Option, then within
thirty (30) days after the determination of the Extension Period Fixed Rent,
Landlord and Tenant shall execute a written supplement to this Lease confirming
the terms, provisions and conditions of this Lease applicable during each
Extension Period; provided, however, that failure to do so shall not affect
either party's rights hereunder.

          31.2.   Terms.
                  -----

                  (a) Each Extension Period shall be upon the same terms and
conditions of this Lease except that: (i) the Fixed Rent during each such
Extension Period shall be set at an annual rate (with annual escalations) equal
to one hundred percent (100%) the annual fair market rental and annual
escalation rate (collectively "FMR") for the applicable Extension Period, as
determined by the agreement of Landlord and Tenant in accordance with the
Renewal Parameters and pursuant to the process described below; (ii) except as
specifically set forth in Section 2.3 of this Lease with respect to the
Surrender Term, Tenant shall have no option to renew the Term beyond the
expiration of the third Extension Period; and (iii) except as otherwise agreed
to by Landlord and Tenant pursuant to the process described below, the Premises
shall be delivered in their existing condition (on an "as is" basis) at the time
the applicable Extension Period commences (provided that the determination of
FMR pursuant to the Renewal Parameters will take this fact and any improvement
and refurbishment allowance then otherwise being provided). Except as
specifically provided in Section

                                       -72-

<PAGE>

31.5, below, any Extension Option of this Lease shall be for all, but not less
than all, of the Premises then leased by Tenant.

          (b) "Renewal Parameters" shall mean all appropriate factors for
determining fair market economics of a new lease or renewal transaction for
similar class office space in buildings of similar quality (taking into account
class and age) in the Reston/Herndon submarket, such appropriate factors to
include the quality, location and visibility of the Building and the
desirability of the Waterview project, the size and type of space being renewed,
the tenant's creditworthiness, any concessions being granted (including rental
abatements, move allowances, tenant improvement allowances, and the like) or
costs being saved, downtime for vacancy, leasing commissions (or the lack
thereof), the method of calculating Additional Rent (i.e., operating costs and
tax pass-throughs), base rental escalations, costs associated with relocation
(or the lack thereof), fees then being charged (or not) in the Reston/Herndon
submarket for parking (it being understood that no separate charge for parking
shall ever be assessed to Tenant under this Lease), the criteria concerning a
security deposit required to be considered under Section 31.6 of this Lease (if
any), and any other criteria or factor that would fairly be taken into
consideration in determining the economics of a market lease transaction in the
Reston/Herndon submarket.

     31.3 Negotiation Process. Within thirty (30) business days after Landlord's
          -------------------
receipt of an Option Notice from Tenant, Landlord will provide to Tenant in
writing its good faith determination of the applicable FMR for the Extension
Period taking into account the Renewal Parameters ("Landlord's FMR Proposal").
The parties thereafter shall negotiate in good faith. If Landlord and Tenant are
unable to reach agreement on the FMR for the applicable Extension Period and
execute a document therefor within sixty (60) days after Tenant's receipt of
Landlord's FMR Proposal, then Tenant may elect, at its option, by written notice
to Landlord: (a) to withdraw its Option Notice (in which event the Option
Notice, all thereupon be null and void); (b) to accept the last written offer
presented by Landlord to Tenant; or (c) to submit the question of what the
appropriate FMR should be for the applicable Extension Period for determination
using the Three Broker Method set forth below. If Tenant fails to notify
Landlord of its election pursuant to the preceding sentence within five (5)
Business Days after the expiration of the 60-day period, Tenant shall be deemed
to have irrevocably withdrawn its Option Notice pursuant to clause (a) above and
the Lease shall terminate in accordance with its terms. If Tenant elects to
proceed under clause (b) or (c) above, the Option Notice shall thereafter be
deemed irrevocable.

     31.4 Three Broker Method. If necessary, the FMR for the applicable
          -------------------
Extension Period shall be determined by brokers in the following manner:

          (a) Landlord and Tenant shall each appoint one broker who is licensed
as a real estate broker in the Commonwealth of Virginia and who shall have been
active over the seven (7) year period ending on the date of the Option Notice in
the leasing of comparable office properties within the Reston/Herndon office
submarket. Each such

                                      -73-

<PAGE>

broker shall be appointed within eleven (11) Business Days after Landlord's
receipt of Tenant's election to proceed under clause (c) of Section 31.3.

          (b) The two brokers so appointed shall, within ten (10) days of the
date of the appointment of the last appointed broker, agree upon and appoint a
third broker who shall be qualified based upon the same criteria set forth
hereinabove for the qualification of the initial two brokers.

          (c) Each of the two (2) brokers initially selected by Landlord and
Tenant shall, within eleven (11) Business Days after the appointment of the
third broker, prepare his or her written determination of the terms which each
such broker believes in good faith constitutes the prevailing FMR taking into
account the Renewal Parameters, and deliver a written copy of such determination
to each of Landlord, Tenant and the third broker. Within eleven (11) Business
Days after the third broker receives the written submissions from each of
Landlord's broker and Tenant's broker, the third broker shall determine which
submission the third broker believes in good faith most closely approximates the
prevailing FMR, and the FMR set forth in such submission shall thereupon
constitute the FMR and be binding on the parties.

          (d) If either Landlord or Tenant fails to appoint a broker within the
time period specified in subparagraph (a) hereinabove or one of the two (2)
brokers initially selected by Landlord and Tenant fails to submit a written
determination within the time period specified in subparagraph (c) above, the
broker appointed by one of them shall reach a decision (within the limitations
set forth in clause (c), and notify Landlord and Tenant thereof. The cost
associated with obtaining the three broker determinations under this Section
shall be divided equally by Landlord and Tenant.

     31.5. Partial Renewal. Tenant may renew this Lease for less than the
           ---------------
entirety of the Premises, but no less than fifty percent (50%) of the Building,
so long as the renewal for less than all of the Premises (hereinafter, a
"Partial Renewal") shall meet all of the following standards: (a) with respect
to each Floor included within any such Partial Renewal, the space renewed shall
be the entirety of such Floor, except (1) with respect to the first Floor, which
shall be for a minimum of 25% of that Floor, and (2) if Tenant is then leasing a
different fractional portion of the Floor in question at the time and is
renewing as to the entirety of such space; and (b) no Partial Renewal will be
permitted which will result in the surrender to Landlord of any non-contiguous
Floors (except for the first floor of the Premises, which may be non-contiguous
to the space surrendered). If Tenant wishes to exercise its Renewal Option for a
Partial Renewal, Tenant's Option Notice shall specify which portion of the
Premises is subject to such Option Notice (and upon the end of the Term then
ending, this Lease shall terminate as to all portions of the Premises which are
not within the scope of such Option Notice).

     31.6 Security Deposit During Extension Period. If Tenant satisfies the
          ----------------------------------------
Financial Condition as of the date of the Option Notice, then Tenant shall not
be required to post any security deposit for such Extension Period. If not, then
the Renewal Parameters shall include consideration of what would constitute an

                                      -74-

<PAGE>

appropriate security deposit securing the performance of Tenant's obligations
with respect to the applicable Extension Period, given Tenant's creditworthiness
at the time, any out-of-pocket expenditures by Landlord in connection with such
renewal, and prevailing market conditions at the time, and Tenant shall be
required to post any such security as a condition to such Extension Term.

                                   ARTICLE 32
                        PURCHASE OPTIONS ON THE BUILDING
                        --------------------------------

     32.1 Primary Purchase Option.
          -----------------------

     (a)  Provided no uncured Material Default shall then exist, Tenant shall
(for itself and for the benefit of any successor, assign or permitted designee
pursuant to section (e) below) have the right and option (the "Primary Purchase
Option") to purchase the Premises in accordance with the terms and conditions
set forth in this Section 32.1 and a Purchase and Sale Agreement (a "PSA") to be
executed by Landlord and Tenant (or Tenant's permitted designee) substantially
in the form of the Purchase and Sale Agreement attached as Exhibit P hereto. In
                                                           ---------
the event of any inconsistencies between the PSA and this Section 32.1, the
terms, covenants and conditions of the PSA shall control.

     (b)  Not later than May 1, 2003, Tenant shall notify Landlord whether
Tenant elects to exercise its Primary Purchase Option (a "Purchase Notice").
Tenant's failure to deliver a Purchase Notice prior to such date shall be deemed
to constitute Tenant's irrevocable election not to so purchase the Property.

     (c)  If Tenant timely delivers the Purchase Notice to Landlord, the entire
Premises (i.e., Building, Land and Parking Garage) shall be sold by Landlord to
Tenant for a purchase price equal the sum of (i) the product of (1) Two Hundred
Ten Dollars ($210.00) and (2) the Agreed Area of the Building, plus (ii) the
total amount of the Supplemental Allowance that was advanced by Landlord and
which remains outstanding at such time. The settlement date shall occur on a
date designated by Tenant (subject to reasonable extension as more particularly
set forth in the PSA) upon at least five (5) Business Days notice to Landlord,
which settlement date shall be at any time at least 30 days after receipt by
Landlord of the Purchase Notice and prior to the 90th day after the Last Rent
Commencement Date; provided, however, that subject to the terms and conditions
of Paragraph C.2 of the Design and Construction Agreement, Tenant shall not
close on a purchase of the Premises prior to October 1, 2002 (the "Lock-Out
Date"). If settlement occurs after such Last Rent Commencement Date, Tenant
shall pay all Rent until such settlement. If settlement occurs prior to such
Last Rent Commencement Date, Landlord shall still be obligated to fund the
Landlord's Contribution and the Supplemental Allowance, and shall reimburse
Tenant for its costs of funds as follows: purchase price (per rentable square
foot for which a Rent Commencement Date has not occurred) x seven percent (7.0%)
per annum (compounded monthly)/365 x number of days between settlement and such
Last Rent Commencement Date. In addition, Landlord shall pay Tenant a liquidated
sum in the

                                      -75-

<PAGE>

amount of $2.50 per rentable square foot per annum (which shall be prorated on a
per diem basis) for all costs incurred in connection with utilities and services
provided during the construction period of the Initial Installations. There
shall be no good faith deposit.

          (d) There will be no brokerage commissions payable by Landlord in
connection with such sale (provided that, as set forth in a separate commission
agreement between Landlord and Broker for Tenant, the second portion of the
commission thereunder allocable to the Premises will be accelerated and will be
payable at closing of the purchase and sale of the Property pursuant to the
PSA).

          (e) Landlord will cooperate in good faith (at no material cost to
Landlord unless Landlord is reimbursed therefor, and provided that no other
obligation or liability of Landlord under this Lease is materially increased (it
being understood, however, that any cost, obligation or liability substantially
identical to that assumed by Landlord elsewhere under this Lease shall be deemed
acceptable to Landlord hereunder) unless Landlord is reimbursed therefor) to
enable Tenant to structure any acquisition as a synthetic lease or other form of
off-balance sheet type transaction. Tenant shall be entitled to certain damages
in connection with a failure to effectuate any such transaction pursuant to
Section 13 of the PSA. Without limiting the generality of the foregoing, Tenant
shall have the absolute right, at its sole option to assign the Primary Purchase
Option or designate any person or entity to whom title to the Property shall be
conveyed (at closing or when otherwise required by a synthetic lease
transaction) in order to facilitate a synthetic lease or other off-balance sheet
financing, provided such assignment shall not in any way (i) constitute an
assignment of this Lease by Tenant, nor (ii) relieve Tenant of any of its
obligations hereunder. Tenant also may assign the Primary Purchase Option in
connection with a permitted assignment under this Lease.

          (f) In the event Tenant exercises its Primary Purchase Option in
accordance herewith, pending the date of closing thereon, Tenant will remain in
possession of the Premises as a "tenant" under this Lease and possession of fee
simple ownership shall be given only upon the consummation of closing under the
PSA.

     32.2 Right of First Offer to Purchase in Future
          ------------------------------------------

          (a) Provided that Tenant is leasing more than 50% of the Agreed Area
of the Building and no uncured Material Default shall then exist, Tenant shall,
throughout the Term, have a continuing right of first offer (a "ROFOP") to
purchase the entirety (but not less than the entirety) of the Premises. If
Landlord shall desire to sell the Premises, or if Landlord shall receive any
unsolicited arm's length offer from an unaffiliated third party to purchase the
Premises that Landlord is willing to entertain, Landlord shall notify Tenant in
writing of same (the "Offer Notice"). The Offer Notice shall disclose to Tenant
the price ("Offer Price") and other material terms pursuant to which Landlord
will be marketing the Premises for sale in good faith or which are contained in
such unsolicited offer. Tenant shall have eleven (11) Business Days following
receipt of the Offer Notice

                                       -76-

<PAGE>

to accept such terms and conditions. The purchase price must be payable in cash
or cash equivalent and such other terms and conditions must not contain any
unique terms which are incapable of being performed by purchasers generally. If
Tenant accepts such terms and conditions during such period, then Landlord and
Tenant shall promptly enter into a purchase and sale agreement in substantially
the form of Exhibit T, with such modifications as may be necessary or
            ---------
appropriate to reflect the terms of the Offer Notice and this Section and to
include any provisions reasonably necessary to qualify the sale transaction for
synthetic lease or other off-balance sheet treatment (which provisions shall not
increase or adversely modify, other than in a de minimis fashion Landlord's, or
any guarantor's, rights, obligations and liabilities set forth in the agreement
attached as Exhibit T) (the "ROFO PSA"). Any dispute regarding the terms of such
            ---------
ROFO PSA shall be subject to arbitration in accordance with Section 34.

          (b) If Tenant withdraws its exercise of its ROFOP, or if Tenant never
elects to exercise its ROFOP, then Landlord shall be free for a period of twelve
(12) months from the expiration of such eleven (11) business day period to sell
the Premises to any third party provided that (i) the sale price is not less
than ninety-five percent (95%) of the purchase price last offered by Landlord to
Tenant, and (ii) the other material business terms are not materially less
favorable to Landlord than those contained in Landlord's last offer to Tenant.
In the event the Premises is not sold within such twelve (12) month period but
is subject to a Pending Contract (as defined below), Landlord shall continue to
be free to sell the Premises upon the terms set forth in the Pending Contract.
If a sale is not consummated within such twelve (12) month period, or if the
purchase price is less than ninety-five percent (95%) of Landlord's last offer
to Tenant or otherwise is materially different, then the ROFOP shall be
reinstated (with Landlord being obligated to take into account in good faith any
such materially less favorable terms, if any) (provided that if Landlord
provided Tenant with a fully-executed letter of intent, memorandum of
understanding or similar agreement for such proposed third party sale, Tenant
shall have eleven (11) business days after receipt of such letter, memorandum or
agreement to agree to the terms of the specific offer stated therein). In the
event the Premises is not sold within such twelve (12) month period but is
subject to a Pending Contract (as defined below), Landlord shall continue to be
free to sell the Premises upon the terms set forth in the Pending Contract. For
purposes of this Section: (x) the term "Pending Contract" shall mean a bona fide
written contract which provides for the sale of the Premises to an unrelated
third party at a sale price not less than ninety-five percent (95%) of the
purchase price last offered by Landlord to Tenant and sets an outside date for
the closing of such sale not later than sixteen (16) months after Tenant's
receipt of the Offer Notice; and (y) a sale of the Premises shall be deemed to
include the sale or transfer of an equity interest in the entity directly or
indirectly owning the Land and/or the balance of the Premises, except to the
extent permitted by subsection (c) below. If a sale is consummated within such
12-month period or pursuant to a Pending Contract, then Tenant shall have no
further ROFOP and this Section 32.2 shall be deemed null and void. Upon request,
Landlord shall deliver to Tenant an unconditional certification signed by an
authorized officer of Landlord stating that the preceding percentage and time
limitations were not violated in connection with such sale.

                                       -77-

<PAGE>

          (c) Notwithstanding anything in this Lease to the contrary, Tenant
shall have no rights pursuant to this Section 32.2 (but shall have all other
rights) in connection with the transfer of title to the Premises, as the case
may be: (i) upon both (A) the foreclosure, or bona fide deed in lieu of
foreclosure, in respect of any Mortgage which was obtained for legitimate
business purposes in order to obtain financing and not for the purpose of
avoiding Tenant's rights or Landlord's obligations under this Lease and (B) the
initial (but only the initial) transfer of such lender taking by foreclosure or
deed in lieu of foreclosure (but only to the extent (1) such lender is
prohibited by applicable regulatory laws regulating such lender's activities in
such circumstances (and Tenant is provided with prior written notice of such
prohibition) from providing any such rights to Tenant and (2) Tenant is
unwilling or unable to modify the affected rights hereunder to enable such
lender to comply with any such laws); provided that in all events the ROFOP
rights shall survive any such foreclosure or deed in lieu of foreclosure, and
such initial transfer, and shall apply to any and all subsequent transfers; (ii)
upon both (A) the bona fide termination for default by Landlord of a Superior
Lease which was obtained for legitimate business purposes in order to obtain
financing and not for the purpose of avoiding Tenant's rights or Landlord's
obligations under this Lease and (B) the initial (but only the initial) transfer
by such terminating landlord (but only to the extent (1) such landlord is
prohibited by applicable regulatory laws regulating such landlord's activities
in such circumstances (and Tenant is provided with prior written notice of such
prohibition) from providing any such rights to Tenant and (2) Tenant is
unwilling or unable to modify the affected rights hereunder to enable such
landlord to comply with any such laws); provided that in all events the ROFOP
rights shall survive any such termination, and any such initial transfer, and
shall apply to any and all subsequent transfers; (iii) to any member of Landlord
or to any Affiliate of Landlord or of any member of Landlord, so long as, after
such transfer, Tishman Speyer Properties, L.P., Tishman Speyer Crown Equities, a
Delaware general partnership, or Tishman Speyer/Traveler's Real Estate Venture,
L.P., either directly or indirectly, through one or more intermediate entities,
(A) exercises Control over the entity which owns title to the Premises and (B)
owns ten percent (10%) or more of the total beneficial interests in the entity
which owns title to the Premises; and (iv) upon the sale or transfer of an
equity interest in the entity directly or indirectly owning the Premises, so
long as, after such transfer, Tishman Speyer Properties, L.P., Tishman Speyer
Crown Equities, a Delaware general partnership or Tishman Speyer/Traveler's Real
Estate Venture, L.P., either directly or indirectly, through one or more
intermediate entities, (A) exercises Control over the entity which owns title to
the Premises and (B) owns ten percent (10%) or more of the total beneficial
interests in the entity which owns title to the Premises. The owner of the
Premises following a transfer in accordance with subsection (c)(iii) and (iv)
shall not be entitled or permitted to sell the Premises during the Term without
first complying again with the ROFOP to Tenant in accordance with the terms of
this Section 32.2.

     32.3 [Reserved]

                                      -78-

<PAGE>

     32.4 Certain Synthetic Lease Covenants. The following provisions shall
          ---------------------------------
apply in connection with the exercise by Tenant of any of its rights under
Section 32.1 in the form of a synthetic lease or other off-balance sheet
transaction notwithstanding any other provision of this Lease to the contrary:

          (a) In the event Tenant's synthetic lease counsel or accountant
informs Landlord that, in such person's good faith, reasonable professional
judgment, one or more provisions of this Lease would prohibit or otherwise
materially adversely affect Tenant's ability to enter into a synthetic lease or
other off-balance sheet transaction, Landlord agrees to amend such Lease
provision provided that (i) Tenant pays all reasonable costs, including
attorneys' fees, associated with so amending the Lease, and (ii) such amendment
shall not materially increase Landlord's obligations or liabilities under this
Lease (it being understood, however, that any cost, obligation or liability
substantially identical to that assumed by Landlord under this Lease shall be
deemed acceptable to Landlord hereunder) and (iii) such amendments shall be
deemed void ab initio if the applicable transaction is not consummated and this
Lease continues.

          (b) Notwithstanding any other provision of this Lease to the contrary,
Landlord acknowledges that Tenant shall have no obligation (other than posting
the Security Deposit and any additional collateral that may be required pursuant
to Section 31.6 of this Lease (concerning the Extension Term), Paragraph C.2(b)
of the Design and Construction Agreement (concerning Lienable Initial
Installations Costs), and Paragraph C.2(h) of the Design and Construction
Agreement (concerning the Lock-Out Allowance, if any)), and Tenant shall not pay
any costs for or relating to the Initial Installations, including Excess TI
Costs, unless and until Landlord has expended the entire Landlord's Contribution
and Supplemental Allowance and Lock-Out Allowance.

          (c) Notwithstanding any other provision of this Lease to the contrary,
with respect to any period prior to the later of (i) the Commencement Date, or
(ii) the date the Primary Purchase Option is consummated, any indemnity being
provided by Tenant under this Lease shall not be applicable, and Tenant shall
not be liable, to (A) any third-parties (including, without limitation,
Landlord's Affiliates and Agents) for any matters, nor (B) Landlord for the
actions of any third-parties, including, without limitation, actions of Tenant's
Agents and Affiliates during such period; provided, however, that Tenant's
indemnity to Landlord for third party claims caused by or resulting from
Tenant's own actions or failures to act (but not Tenant's Agents and Affiliates)
during such period shall apply.

          (d) In no event shall Tenant incur or be responsible for any
Environmental Liabilities existing as of, or any Hazardous Materials introduced
to the Premises prior to, or any Hazardous Materials Release occurring prior to,
the Commencement Date, except to the extent of an indemnity to Landlord arising
solely out of the acts and/or omissions of Tenant and/or Tenant's Agents.

                                      -79-

<PAGE>

          (e) Subsections (c) and (d) shall each be deemed void ab initio with
respect to the Premises and this Lease if the applicable transaction is not
consummated as and when provided herein and this Lease continues.

                                   ARTICLE 33
                                     SIGNAGE
                                     -------

     Section 33.1 (a) So long as Tenant is leasing at least 75% of the Agreed
Area of the Building, Tenant shall have the exclusive right to install and
construct Building mounted signage on Waterview I (to the maximum extent
permissible by law) (not including, however, retail signage approved by Tenant
(which shall not reduce Tenant's signage), such approval not to be unreasonably
withheld, conditioned or delayed) anywhere on the Premises, provided the
location, size and appearance of all signage is consistent with the design
specifications package governing Woodland Park attached hereto as Exhibit Y, and
                                                                  ---------
Landlord has reasonably approved the means of attaching such signage to the
exterior of the Building. All such installations shall be subject to Article 5
                                                                     ---------
hereof, other than Section 5.1(a)(iii) and Section 5.1(a)(vi).

     Section 33.2 Tenant shall be entitled to non-exclusive use of the lobby
directory in the Building and Tenant may display its name and logo on the lobby
of each Floor; provided, however, if Tenant leases 100% of the Agreed Area,
Tenant's rights under this Section 33.2 shall be exclusive. All signage provided
by this Section shall be at Tenant's sole expense, with the exception of the
lobby directory which shall be provided by Landlord at Landlord's expense.

     Section 33.3 In accordance with the Design and Construction Agreement,
Landlord will name the road leading to Waterview I (as shown on Exhibit M) as
                                                                ---------
"VeriSign Way" for so long as Tenant leases all of the office area of Waterview
I. After Waterview II is completed, if one or more full Floors of Waterview II
is not leased by Tenant, Landlord shall have the right to rename such road if
appropriate in Landlord's reasonable judgment to accommodate other Waterview II
or III tenant requirements; provided that Landlord shall use good faith and
diligent efforts to either maintain such named road or to rename a different
road (or portion of the same road) leading to Waterview I.

     Section 33.4 Any assignee of this Lease who meets the Secondary Financial
Condition, and any Tenant Affiliate, shall be entitled to all signage rights
afforded to Tenant. In addition, all such rights shall continue in favor of
Tenant notwithstanding any permitted sublease (and Tenant may exercise same for
its own use or as an accommodation to its subtenant).

     Section 33.5 In connection with the Standard Base Building Work, Landlord
shall provide monument signage for Tenant on the Land at the entrance to
Waterview closest to Centreville Road in the location shown on Exhibit W. In
                                                               ---------
addition, Landlord will also provide monument signage for Tenant and other
tenants of Waterview on the Land at one or more locations deemed appropriate by
Landlord. Such signage installed

                                      -80-

<PAGE>

pursuant to this Section 33.5 shall have Tenant's name/logo being exclusive or
at least the most prominent so long as Tenant is leasing the most space in
Waterview.

     Section 33.6. So long as Tenant occupies 50% or more of the Building, none
of the following entities shall have any exterior building or monument signage
at Waterview: Baltimore Technologies, Entrust, Verizon, Nortel Networks, and
Register.com (collectively, "Competitors"). No corporate or entity name or
identification, except that of a Permitted Entity, shall ever be used in naming
either Waterview or Woodland Park. A "Permitted Entity" means any entity that
(a) is not a tenant user or occupant in Woodland Park or a Competitor, and (b)
is an entity the primary business of which is real estate development or
investment.

                                   ARTICLE 34
                                   ARBITRATION
                                   -----------

     Section 34.1 Arbitration. No dispute arising out of this Lease shall be
                  -----------
determined by arbitration unless specifically provided herein.

     Section 34.2 Expedited Arbitration of Other Disputes. In any dispute
                  ---------------------------------------
between Landlord and Tenant for which arbitration is specifically provided for
hereunder, Landlord and Tenant agree that: (a) upon the request of either
Landlord or Tenant, the dispute shall be submitted to the American Arbitration
Association or its successor (the "AAA") for disposition pursuant to the
"Expedited Procedures" of the AAA by the Washington, D.C. office of the AAA; (b)
the decision of the AAA shall be final and all actions necessary to implement
the decision of the AAA shall be undertaken as soon as possible, but in no event
later than ten (10) Business Days after the rendering of such decision; (c)
judgment upon the dispute or any award rendered may be entered in any court
having jurisdiction thereof; and (d) all fees payable to the AAA for services
rendered in connection with the resolution of the dispute shall be paid by the
unsuccessful party (in the event of any dispute regarding which party was
unsuccessful, the determination of the arbitrator with respect thereto shall be
final). For purposes of this Section 34.2, the phrase "Expedited Procedures of
the Association" shall mean those procedures set forth in paragraphs 53 through
57 of that certain booklet published by the Association and titled "Commercial
                                                                    ----------
Arbitration Rules", as effective on November 1, 1993 and any amendments thereto.
-----------------

                                   ARTICLE 35
                                SECURITY DEPOSIT
                                ----------------

     Section 35.1 Security Deposit. Within thirty (30) days after full and final
                  ----------------
execution of this Lease by Landlord and Tenant, Tenant shall deposit the
Security Deposit in the form of a letter of credit with Landlord as security for
the faithful performance and observance by Tenant of the terms, covenants and
conditions of this Lease, including the surrender of possession of the Premises
to Landlord as herein provided. Landlord acknowledges that, due to the
possibility of a synthetic lease or similar transaction, Landlord shall not use
the Security Deposit (or any other deposit) for

                                      -81-

<PAGE>

construction funds unless Tenant is ineligible to purchase the Premises pursuant
to Section 32.1 of this Lease.

         Section 35.2 Letter of Credit. Tenant shall deliver the Security
                      ----------------
Deposit to Landlord in the form of an irrevocable and unconditional letter of
credit (the "Letter of Credit") issued by and drawable upon Bank of America in
Los Angeles, California, or other commercial bank, trust company, national
banking association or savings and loan association reasonably satisfactory to
Landlord with offices for banking purposes in Northern Virginia or New York, New
York (the "Issuing Bank"), which has outstanding unsecured, uninsured and
unguaranteed indebtedness, or shall have issued a letter of credit or other
credit facility that constitutes the primary security for any outstanding
indebtedness (which is otherwise uninsured and unguaranteed), that is then
rated, without regard to qualification of such rating by symbols such as "+" or
"-" or numerical notation, "Aa" or better by Moody's Investors Service and "AA"
or better by Standard & Poors Rating Service, and has combined capital, surplus
and undivided profits of not less than $2,000,000,000. Such Letter of Credit
shall (a) name Landlord as beneficiary, (b) be in the amount of the Security
Deposit, (c) have a term of not less than one year, (d) permit multiple
drawings, and (e) otherwise be substantially in the form set forth on Exhibit G
                                                                      ---------
hereto. If upon any transfer of the Letter of Credit, any fees or charges shall
be so imposed, then such fees or charges shall be payable solely by Tenant and
the Letter of Credit shall so specify. The Letter of Credit shall provide that
it shall be deemed automatically renewed, without amendment, for consecutive
periods of one year each thereafter during the Term unless the Issuing Bank
sends a notice (the "Non-Renewal Notice") to Landlord, with a copy to Landlord's
Chief Financial Officer, by certified mail, return receipt requested, not less
than forty-five (45) days next preceding the then expiration date of the Letter
of Credit stating that the Issuing Bank has elected not to renew the Letter of
Credit. Unless Tenant substitutes a new Letter of Credit not less than twenty
(20) days prior to the expiration date of the Letter of Credit, Landlord shall
have the right, upon receipt of the Non-Renewal Notice, to draw the full amount
of the Letter of Credit, by sight draft on the Issuing Bank, and shall
thereafter hold or apply the cash proceeds of the Letter of Credit pursuant to
the terms of this Article 35. The Issuing Bank shall agree that drafts drawn
                  ----------
under and in compliance with the terms of the Letter of Credit will be duly
honored upon presentation to the Issuing Bank at an office location in Northern
Virginia, Washington, D.C. or New York, New York. The Letter of Credit shall be
subject in all respects to the Uniform Customs and Practice for Documentary
Credits (1993 revision), International Chamber of Commerce Publication No. 500.

         Section 35.3 Application of Security. If, following the expiration of
                      -----------------------
any applicable notice and grace periods (except in the event of a Tenant
bankruptcy, for which no grace or cure period shall apply), Tenant defaults in
the payment or performance of any of the terms, covenants or conditions of this
Lease, including the payment of Rent, Landlord may notify the Issuing Bank and
thereupon receive all or a portion of the Security Deposit represented by the
Letter of Credit and use, apply, or retain the whole or any part of such
proceeds, as the case may be, to the extent required for the payment of any
Fixed Rent or any other sum as to which Tenant is in default including

                                      -82-

<PAGE>

(a) any sum which Landlord may expend or may be required to expend by reason of
Tenant's default under the terms of this Lease, and/or (b) any damages or
Deficiency to which Landlord is entitled pursuant to this Lease or applicable
Requirements, whether such damages or Deficiency accrues before or after summary
proceedings or other reentry by Landlord. If Landlord so applies or retains any
part of the Security Deposit, Tenant, upon demand, shall deposit with Landlord
the amount so applied or retained so that Landlord shall have the full Security
Deposit on hand at all times during the Term. To the extent not so applied, the
Security Deposit shall be returned to Tenant after the Expiration Date and after
delivery of possession of the Premises to Landlord in the manner required by
this Lease, and Landlord shall authorize the issuing bank to terminate the
Letter of Credit. Tenant expressly agrees that Tenant shall have no right to
apply any portion of the Security Deposit against any of Tenant's obligations to
pay Rent hereunder.

         Section 35.4 Transfer. Upon a sale of the Land and/or the Building or a
                      --------
leasing of the Building, or any financing of Landlord's interest therein,
Landlord shall have the right to transfer any cash Security Deposit or the
Letter of Credit, as applicable, to the vendee, lessee or lender, provided such
vendee, lessee or lender assumes Landlord's obligations hereunder with respect
to the cash Security Deposit or the Letter of Credit, as applicable. With
respect to the Letter of Credit, within ten (10) Business Days after notice of
such sale, leasing or financing, Landlord (with Tenant's cooperation), at its
sole cost, shall arrange for the transfer (by amendment) of the Letter of Credit
to the new landlord or the lender, or have the Letter of Credit reissued in the
name of the new landlord or the lender. To the extent so transferred, Tenant
shall look solely to the new landlord or lender for the return of such cash
Security Deposit or Letter of Credit and the provisions hereof shall apply to
every transfer or assignment made of the Security Deposit to a new landlord.
Tenant shall not assign or encumber or attempt to assign or encumber the cash
Security Deposit or Letter of Credit and neither Landlord nor its successors or
assigns shall be bound by any such action or attempted assignment, or
encumbrance.

         Section 35.5 Reduction.
                      ---------

                  (a) Provided (i) no uncured Material Default shall then exist
and (ii) Tenant satisfies the Financial Condition, then on the first day of each
Lease Year, commencing with the first day of the 2/nd/ Lease Year, and
continuing annually thereafter on the first day of each subsequent Lease Year in
which Tenant qualifies for reduction (each such anniversary date, a "Reduction
Date"), Tenant shall have the right to reduce the Security Deposit (a
"Reduction") to the amount set forth in the following schedule (the "Reduction
Schedule"):

                         Reduction Date                  Amount
                         --------------                  ------

                First Day of Lease Year #2         $12,727,272.73
                First Day of Lease Year #3         $11,454,545.46
                First Day of Lease Year #4         $10,181,818.19
                First Day of Lease Year #5         $ 8,909,090.92

                                      -83-

<PAGE>

                First Day of Lease Year #6         $  7,636,363.65
                First Day of Lease Year #7         $  6,363,636.38
                First Day of Lease Year #8         $  5,090,909.11
                First Day of Lease Year #9         $  3,818,181.84
                First Day of Lease Year #10        $  2,545,454.57
                First Day of Lease Year #11        $  1,272,727.30
                End of Initial Term                $   0.00 (subject to
                                                       Section 31.1 (renewals))

                  (b) Provided Tenant qualifies as of any such Reduction Date,
such Reduction shall be effectuated by Tenant's delivery of either (i) a
replacement letter of credit for the applicable lesser amount, which replacement
letter of credit may (a) include an endorsement that provides that such
replacement Letter of Credit shall be effective only upon Landlord's return of
the Letter of Credit being replaced or Landlord's written consent to
cancellation of the letter of credit being replaced, or (b) be delivered
pursuant to an escrow arrangement otherwise reasonably approved by Landlord and
Tenant, or (ii) at least eleven (11) Business Days prior to the effective date
of such Reduction, a written amendment to the Letter of Credit which has the
effect of reducing the amount of the Letter of Credit to the lesser amount
determined pursuant to this Section as of the applicable Reduction Date.

                  (c) (1) If Tenant does not qualify for a Reduction as of any
applicable Reduction Date (whether due to the pendency of Material Default or
because of Tenant's failure to satisfy the Financial Condition as of such
Reduction Date, or both), but Tenant subsequently does qualify for such
Reduction as of a later Reduction Date, then Tenant shall be permitted to "catch
up" all prior foregone Reductions as of the applicable Reduction Date. (For
example, if Tenant had never previously qualified for a Reduction, but did so
effective as of the Reduction Date coinciding with the first day of Lease Year
#5, then the Security Deposit would be reduced from $14,000,000.00 to
$8,909,090.92 as of such Reduction Date.)

                      (2) Conversely, if a Reduction has occurred at any time
(or times) during the first five (5) Lease Years, but on a subsequent Reduction
Date during such five-Lease Year period Tenant fails to satisfy the Financial
Condition as of such Reduction Date, Tenant shall, upon written demand, restore
the Security Deposit to its original amount. The failure to do so within thirty
(30) days after demand shall be a Material Default. After such five-Lease Year
period, subsection (1) above shall control. (For example, if Tenant was entitled
to a reduction in Lease Year #2, lost it in Lease Year #3, and did not satisfy
the Financial Condition again until Lease Year #7, then the Security Deposit
would be $11,454,545.46, $14,000,000, and $6,363,636.38 for those respective
Lease Years.)

                                      -84-

<PAGE>

                                   ARTICLE 36
                                  MISCELLANEOUS
                                  -------------

         Section 36.1 Delivery. This Lease shall not be binding upon Landlord or
                      --------
Tenant unless and until each party shall have executed and delivered a fully
executed copy of this Lease to the other party and the Condition Precedent shall
have been satisfied or waived by Tenant.

         Section 36.2 Transfer of Premises. Landlord's obligations under this
                      --------------------
Lease shall not be binding upon the Landlord named herein after the sale,
conveyance, assignment or transfer (collectively a "Transfer") by such Landlord
(or upon any subsequent landlord after the Transfer by such subsequent landlord)
of its interest in the Premises, as the case may be, and in the event of any
such Transfer, Landlord (and any such subsequent Landlord) shall be entirely
freed and relieved of all covenants and obligations of Landlord hereunder
thereafter to be performed, provided that the transferee of Landlord's interest
(or that of such subsequent Landlord) in the Premises shall have assumed in
writing all obligations of Landlord under this Lease thereafter to be performed
and provided such writing to Tenant.

         Section 36.3 Limitation on Liability. The liability of Landlord for
                      -----------------------
Landlord's obligations under this Lease shall be limited to Landlord's interest
in all of Waterview and the net proceeds of (i) any sale, conveyance, assignment
or transfer of the Premises, and (ii) casualty, title or other insurance
policies relating thereto, and Tenant shall not look to any other property or
assets of Landlord or the property or assets of any partner, member,
shareholder, director, officer, principal, employee or agent, directly and
indirectly, of Landlord (collectively, the "Parties") in seeking either to
enforce Landlord's obligations under this Lease or to satisfy a judgment for
Landlord's failure to perform such obligations; and none of the Parties shall be
personally liable for the performance of Landlord's obligations under this
Lease.

         Section 36.4 Rent. Notwithstanding anything to the contrary contained
                      ----
in this Lease, all amounts payable by Tenant to or on behalf of Landlord under
this Lease, whether or not expressly denominated Fixed Rent, Tenant's Tax
Payment, Tenant's Operating Expense Payment, Additional Rent or Rent, shall
constitute rent for the purposes of Section 502(b)(6) of the United States
Bankruptcy Code.

         Section 36.5 Entire Document. This Lease (including any Schedules and
                      ---------------
Exhibits referred to herein and all supplementary agreements provided for herein
as set forth on Exhibit H) contains the entire agreement between the parties and
                ---------
all prior negotiations and agreements are merged into this Lease. All of the
Schedules and Exhibits attached hereto are incorporated in and made a part of
this Lease, provided that in the event of any inconsistency between the terms
and provisions of this Lease and the terms and provisions of the Schedules and
Exhibits hereto, the terms and provisions of this Lease shall control. All
Article and Section references set forth herein shall, unless the context
otherwise requires, be deemed references to the Articles and Sections of this
Lease.

                                      -85-

<PAGE>

         Section 36.6 Governing Law. This Lease shall be governed in all
                      -------------
respects by the laws of the Commonwealth of Virginia (but not including the
choice of law rules thereof).

         Section 36.7 Unenforceability. If any provision of this Lease, or its
                      ----------------
application to any Person or circumstance, shall ever be held to be invalid or
unenforceable, then in each such event the remainder of this Lease or the
application of such provision to any other Person or any other circumstance
(other than those as to which it shall be invalid or unenforceable) shall not be
thereby affected, and each provision hereof shall remain valid and enforceable
to the fullest extent permitted by law.

         Section 36.8 Lease Disputes.
                      --------------

                      (a) Each of Landlord and Tenant agrees that all disputes
arising, directly or indirectly, out of or relating to this Lease, and all
actions to enforce this Lease, shall be dealt with and adjudicated in the state
courts of the Commonwealth of Virginia or the United States District Court for
the Eastern District of Virginia and each of Landlord and Tenant for that
purpose hereby expressly and irrevocably submits itself to the jurisdiction of
such courts. Each of Landlord and Tenant agrees that so far as is permitted
under applicable law, this consent to personal jurisdiction shall be
self-operative and no further instrument or action, other than service of
process in one of the manners specified in this Lease, or as otherwise permitted
by law, shall be necessary in order to confer jurisdiction upon it in any such
court.

                      (b) To the extent that either Landlord or Tenant has or
hereafter may acquire any immunity from jurisdiction of any court or from any
legal process (whether through service or notice, attachment prior to judgment,
attachment in aid of execution, execution or otherwise) with respect to itself
or its property, each of Landlord and Tenant irrevocably waives such immunity in
respect of its obligations under this Lease.

         Section 36.9 Landlord's Agent. Unless Landlord shall render written
                      ----------------
notice to Tenant to the contrary, Tishman Speyer Properties, L.P. is authorized
to act as Landlord's Agent in connection with the performance of this Lease, and
Tenant shall direct all correspondence and requests to, and shall be entitled to
rely upon correspondence received from, Tishman Speyer Properties, L.P., as
agent for the Landlord in accordance with Article 26. Tenant acknowledges that
                                          ----------
Tishman Speyer Properties, L.P. is acting solely as agent for Landlord in
connection with the foregoing; and neither Tishman Speyer Properties, L.P. nor
any of its direct or indirect partners, officers, shareholders, directors,
employees, principals, agents or representatives shall have any liability to
Tenant for the performance of Landlord's obligations under this Lease, and
Tenant waives any and all claims against any and all of such parties for the
performance of Landlord's obligations under this Lease, regardless of whether
performed by Landlord or Landlord's Agent.

         Section 36.10 Estoppels.
                       ---------

                                      -86-

<PAGE>

                 (a)   Within eleven (11) Business Days following a written
request from Landlord or any Mortgagee or Lessor, Tenant shall deliver to
Landlord a written statement executed and acknowledged by Tenant, in form
reasonably satisfactory to Landlord and Tenant, (a) stating the Effective Date,
the Commencement Date, all Rent Commencement Dates and the Expiration Date, and
that this Lease is then in full force and effect and has not been modified (or
if modified, setting forth all modifications), (b) setting forth the date to
which the Fixed Rent and any Additional Rent have been paid, together with the
amount of monthly Fixed Rent then payable, (c) stating whether or not, to the
best of Tenant's knowledge, Landlord is in default under this Lease, and, if
Landlord is in default, setting forth the specific nature of all such defaults,
(d) stating the amount of the Security Deposit, if any, under this Lease, (e)
stating whether there are any subleases or assignments affecting the Premises,
(f) stating the address of Tenant to which all notices and communication under
the Lease shall be sent, and (g) responding to any other matters of a factual
nature reasonably requested by Landlord or such Mortgagee or Lessor. Tenant
acknowledges that any statement delivered pursuant to this Section 36.10 may be
relied upon by any purchaser or owner of the Premises, or all or any portion of
Landlord's interest in the Premises, or by any Mortgagee or Lessor, or assignee
thereof.

                 (b)   Within eleven (11) Business Days following a written
request from Tenant, Landlord shall deliver to Tenant a written statement
executed and acknowledged by Landlord, in form reasonably satisfactory to Tenant
and Landlord, (a) stating the Effective Date, the Commencement Date, all Rent
Commencement Dates and the Expiration Date, and that this Lease is then in full
force and effect and has not been modified (or if modified, setting forth all
modifications), (b) setting forth the date to which the Fixed Rent and any
Additional Rent have been paid, together with the amount of monthly Fixed Rent
then payable, (c) stating whether or not, to the best of Landlord's knowledge,
Tenant is in default under this Lease, and, if Tenant is in default, setting
forth the specific nature of all such defaults, (d) stating the amount of the
Security Deposit, if any, under this Lease, (e) stating the address of Landlord
to which all notices and communication under the Lease shall be sent, and (f)
responding to any other matters of a factual nature reasonably requested by
Tenant. Landlord acknowledges that any statement delivered pursuant to this
Section 36.10 may be relied upon Tenant, or any assignee thereof.

         Section 36.11 Certain Interpretational Rules. For purposes of this
                       ------------------------------
Lease, whenever the words "include," "includes," or "including" are used, they
shall be deemed to be followed by the words "without limitation" and, whenever
the circumstances or the context requires, the singular shall be construed as
the plural, the masculine shall be construed as the feminine and/or the neuter
and vice versa. This Lease shall be interpreted and enforced without the aid of
    ----------
any canon, custom or rule of law requiring or suggesting construction against
the party drafting or causing the drafting of the provision in question.

         Section 36.12 Captions. The captions in this Lease are inserted only as
                       --------
a matter of convenience and for reference and in no way define, limit or
describe the scope of this Lease or the intent of any provision hereof.

                                      -87-

<PAGE>

         Section 36.13 Parties Bound. The terms, covenants, conditions and
                       -------------
agreements contained in this Lease shall bind and inure to the benefit of
Landlord and Tenant and, except as otherwise provided in this Lease, to their
respective legal representatives, successors, and assigns.

         Section 36.14 Counterparts. This Lease may be executed in two or more
                       ------------
counterparts, each of which shall constitute an original, but all of which, when
taken together, shall constitute but one instrument.

         Section 36.15. No Third Party Beneficiary. This Lease is for the sole
                        --------------------------
and exclusive benefit of the parties hereto and their respective successors and
assigns, and no third party is intended to or shall have any rights hereunder.

         Section 36.16. Rule Against Perpetuities. If the rule against
                        -------------------------
perpetuities or any other rule of law limits the time during which any provision
of this Lease shall be effective, then each such provision shall continue to be
effective until twenty-one (21) years after the death of the last survivor of
all of the members of the Senate of the United States of America, now serving,
and all of their children and grandchildren living on the date of execution of
this Lease.

         Section 36.17. Reasonableness. Unless otherwise expressly provided
                        --------------
herein: each party hereto shall act, and shall cause their respective
architects, engineers, contractors, agents and employees to act, reasonably and
in good faith in satisfying their obligations and where one party's consent or
approval is sought by the other party, such consent or approval shall not be
unreasonably withheld, delayed or conditioned.

         Section 36.18. Fees and Expenses. Except as otherwise provided for in
                        -----------------
this Lease, each party hereto shall pay its own fees, costs and expenses
incurred in connection with this Lease and in the preparation for and
consummation of the transactions provided for herein. In the event of any
litigation arising out of or connected with this Lease, the prevailing party
shall be entitled to recover from the non-prevailing party all reasonable
attorneys' fees and costs incurred therein.

         Section 36.19. Survival. In addition to any provisions which, by their
                        --------
express terms, survive the expiration or earlier termination of this Lease, the
parties agree that (i) all monetary obligations and (ii) all other obligations
which by their nature will not be fully discharged as of the expiration or
earlier termination of this Lease, shall survive such expiration or termination
and continue in full force and effect until fully discharged.

         Section 36.20. Time of Essence.  Time shall be of the essence of this
                        ---------------
Lease and each and every provision hereof.

         Section 36.21. Deed of Lease; Resident Agent.  Landlord hereby
                        -------------- --------------
designates James C. Brincefield, Jr., attorney-at-law, at the following address:
526 King Street, Alexandria, Virginia 22314 to serve as Landlord's resident
agent to receive service of process and other applicable notices pursuant to Va.
Codes (S)55-218.1 (1950)

                                      -88-

<PAGE>

as amended. For the purposes of Va. Code, Section 55-2 (1950) as amended, this
Lease is and shall be deemed to be a Deed of Lease.

         Section 36.22. Recordation. Except to the extent otherwise required by
                        -----------
law, neither Landlord nor Tenant shall record this Lease, provided that (i) a
short form memorandum hereof (in the form attached as Exhibit O and (ii) a short
                                                      ---------
form memorandum of any purchase option specified herein (in the form attached as
Exhibit S) may both be recorded at the request of either Landlord or Tenant,
---------
provided the party requesting such recordation shall pay all costs, expenses and
recordation taxes associated therewith. If recorded, each party covenants to
execute and acknowledge upon the request of the other, a valid release of such
memorandum, in recordable form, upon the expiration or earlier termination of
this Lease or the rights referenced therein.

                                   ARTICLE 37
                              CONDITIONS PRECEDENT
                              --------------------

         Notwithstanding anything in this Lease to the contrary, this Lease is
not effective and binding on Tenant (with respect to Sections 37.2, 37.3 and
37.4), and Landlord and Tenant (with respect to Section 37.1, other than for
Section 37.1 itself and Landlord's payment obligations thereunder) until
satisfaction of the following conditions precedent (collectively, the
"Conditions Precedent"). Satisfaction of all conditions in this Article 37 shall
                                                                ----------
be deemed satisfaction of the "Conditions Precedent". If any of the Conditions
Precedent specified in Sections 37.2, 37.3 and 37.4 are not satisfied at the
time of satisfaction of the Condition Precedent specified in Section 37.1, then,
at Tenant's option, Tenant shall have the right, at any time prior to the
earlier of (a) satisfaction of all such conditions or (b) the 30/th/ day after
satisfaction of the Conditions Precedent specified in Section 37.1, to terminate
this Lease upon written notice to Landlord. Until such termination, Tenant also
shall have the right to attempt to cause satisfaction of any such condition
itself, subject to the self-help provisions of Section 19.2 of this Lease.

         Section 37.1. WinStar Rejection. Landlord shall deliver and Tenant
                       -----------------
shall receive a binding, unconditional and non-appealable order issued by the
United States Bankruptcy Court for the District of Delaware in re WinStar
Communications, Inc., et al., Case No. 01-1430; Chapter 11 proceeding
authorizing and directing the rejection of the unexpired term of the WinStar
lease (and such lease) currently encumbering the Building and any other
interests WinStar may have in either the Building, the Land, any Option
Building, or Waterview (including, without limitation, a valid, recordable
release and termination of any interest in Waterview, including the rooftop,
roof equipment, roof licenses, etc.) (the "Order"). In the event Landlord is
unable to obtain and deliver the Order to Tenant on or before October 1, 2001,
then Tenant shall have the right, at Tenant's sole and absolute discretion, for
any reason or no reason, to terminate this Lease at any time until the Order is
so delivered to Tenant, by giving written notice of such termination to
Landlord. Upon any such termination, neither party shall have any

                                       -89-

<PAGE>

further obligation to the other except that Landlord shall pay to Tenant, within
thirty (30) days after the date of such termination notice, an amount equal to
the sum of (a) all actual out-of-pocket costs and expenses incurred by Tenant in
connection with this Lease and Tenant's potential occupancy of the Premises for
which Tenant has submitted reasonably detailed invoices, and (b) a liquidated
amount equal to $2,000,000.00. Landlord acknowledges that Tenant's damages are
impossible to quantify and that the aforesaid amount is deemed to be a
liquidated damage payment and not a penalty. Notwithstanding the foregoing,
Landlord shall have the right (which may be exercised only twice) to extend its
deadline for securing the Order by an additional thirty (30) days by notifying
Tenant of its election to extend at least one (1) Business Day prior to the
applicable deadline (i.e., from October 1, 2001 to November 1, 2001, and from
November 1, 2001 to December 1, 2001). Each time Landlord elects to extend its
deadline for securing the Order, the amount in subsection (b) of this Section
37.1 shall be increased by $1,000,000.

         Section 37.2 SNDA. At the time the condition specified in Section 37.1
                      ----
is satisfied, if and only if there is a Mortgagor or Lessor in existence
pursuant to Article 10, then Landlord shall deliver, and Tenant shall receive or
refuse receipt thereof, the Non-Disturbance Agreement required in accordance
with Section 10.5. Thereafter, the foregoing condition of Section 37.2 shall be
deemed waived by Tenant subject to Section 10.5 (with any subordination of this
Lease being conditioned on Tenant's receipt of a Non-Disturbance Agreement).

         Section 37.3 Title Matters. At the time the condition specified in
                      -------------
Section 37.1 is satisfied, Landlord shall have delivered to Tenant and
Commonwealth Land Title Insurance Company (the "Title Company") any and all
items reasonably requested by the Title Company to satisfy the conditions listed
on Schedule B, Section 1 of Tenant's Title Commitment No. 010415, dated April
26, 2001 (Rev. 6/23/01) ("Tenant's Title Commitment"), which Schedule B-1
(marked to show the conditions Landlord must satisfy) is attached as Exhibit Z
                                                                     ---------
hereto.

         Section 37.4 Title to Waterview. At the time the condition specified in
                      ------------------
Section 37.1 is satisfied, Landlord shall have delivered to Tenant and the Title
Company a file-stamped copy of a recorded Special Warranty Deed transferring.
without restriction, title to all of the Adjacent Property (which was previously
deeded to TST Woodland, L.L.C. pursuant to the Deed recorded in the land records
of Fairfax County, Virginia at Deed Book 10163 at Page 1290) to Landlord so that
Landlord is the sole fee simple owner to all of Waterview.

         Section 37.5. Real Estate Brokerage Commission Agreement. At the time
                       ------------------------------------------
the condition specified in Section 37.1 is satisfied, Landlord shall have
delivered to Tenant a copy of a fully executed Real Estate Brokerage Commission
Agreement by and between Landlord and Broker for Tenant.

                                       -90-

<PAGE>

                                   ARTICLE 38
                             ASSOCIATION DECLARATION
                             -----------------------

         Section 38.1 During the Term, but only so long as Tenant is leasing
100% of the Agreed Area of the Building, Landlord agrees that it shall not take
any action, nor approve any amendment to the Declaration, nor vote on any
matter, nor permit any Landlord Affiliate to take any action, approve any
amendment to the Declaration or vote on any matter, whether in its capacity as
Declarant or in its capacity as owner of the Land, which would materially
adversely affect either (i) Tenant's use or enjoyment of the Premises or rights
under the Lease or (ii) the economic obligations applicable to the Premises (and
thus payable by Tenant under this Lease) in a discriminatory manner relative to
other tenants at Woodland Park, without first obtaining Tenant's consent
thereto, which consent may not be unreasonably withheld, conditioned or delayed.
In addition, to the extent the Association Declaration grants to Landlord the
right to consult with regard to, or participation in decisions relating to,
amenities for the benefit of Waterview or Woodland Park (or any portion
thereof), Landlord agrees that, so long as Tenant is leasing 100% of the Agreed
Area of the Building, it will not exercise those rights (and that it will cause
Declarant not to exercise such rights) during the Term without first consulting
with Tenant and affording Tenant a meaningful opportunity to participate in such
decisions or consultations.

         Section 38.2 Landlord agrees to cause Declarant to enter into a binding
letter agreement with Tenant (and deliver such letter agreement upon the
delivery of this Lease) in the form of Exhibit R, hereto, under which Declarant,
                                       ---------
among other things, irrevocably approves certain aspects of the proposed design
of the Building, equipment planned to be installed by Tenant within the Land,
and other matters relating to Tenant's planned occupancy that relate to the
Association Declaration. Landlord further agrees to vote, in its capacity as an
Owner under the Association Declaration, in the manner described in such letter.
Landlord shall ensure that such letter is part of the official records of the
Association for public view.

         Section 38.3 Landlord hereby agrees that the Association and the
Association Declaration shall not be administered in any manner that would be
discriminatory against Tenant or have an effect on Tenant disproportionate to
that on all other tenants in Woodland Park. Tenant shall have the right to
review and approve fees and assessments of the Association consistent with
Section 8.4(a).

         Section 38.4 So long as one or more of Landlord's Affiliates is the
Declarant under the Association, Landlord shall cause such Affiliates to
administer the Association Declaration, and to exercise all consents and
approvals thereunder, in a manner consistent with the standards for Landlord's
consent and approval under this Lease.

         Section 38.5 Tenant shall have the right to approve any amendments to
the Association Declaration which would have an effect on Tenant
disproportionate to that on all other tenants in Woodland Park.

                                      -91-

<PAGE>

                                   ARTICLE 39
                                EXPANSION OPTIONS
                                -----------------

         In order to accommodate Tenant's desire for certain options for future
expansion into Waterview II and Waterview III, simultaneously with its execution
of this Lease, Landlord agrees to execute and deliver to (and with) Tenant that
certain "Option Agreement" which is attached as Exhibit Q, and execute, deliver
                                                ---------
and record that certain "Memorandum of Option" attached as an exhibit to the
Option Agreement.

                            [SIGNATURE PAGE FOLLOWS.]

                                      -92-

<PAGE>

                  IN WITNESS WHEREOF, Landlord and Tenant have executed this
Lease as of the day and year first above written.

                                LANDLORD:
                                --------

                                TST WATERVIEW I, L.L.C.,
                                a Delaware limited liability company

                                By:_______________________(SEAL)

                                Name: __________________________

                                Title: _________________________

                                TENANT:
                                ------

                                VERISIGN, INC.,
                                a Delaware corporation

                                By:_______________________(SEAL)

                                Name: __________________________

                                Title: _________________________

<PAGE>

                                    EXHIBIT A
                                    ---------

                             Description of the Land
                             -----------------------

Beginning at an iron pipe set marking the intersection of the southeasterly
right-of-way line of Centreville Road (Route 657) and the southerly right-of-way
line of the Dulles Access and Toll Road (Route 267);

thence with said right-of-way line of the Dulles Access and Toll Road, the
following five (5) courses:

         S 69(degrees) 43' 30" E, 135.89 feet to an iron pipe found

         S 72(degrees) 21' 11" E, 275.02 feet to an iron pipe set

         S 69(degrees) 04' 14" E, 434.33 feet to an iron pipe set;

         S 79(degrees) 08' 10" E, 255.41 feet to an iron pipe set marking the
         point of curvature of a non-tangent curve to the left and

         48.14 feet along the arc of said curve having a radius of 8,794.40 feet
         and a chord bearing and chord of S68(degrees) 28' 07" E, 48.14 feet
         respectively,

to an iron pipe set marking the most northerly corner of now or formerly
National Rural Utilities Cooperative Finance Corporation;

thence departing said Dulles Access and Toll Road and with the northerly lines
of said National Rural Utilities Cooperative Finance Corporation the following
four (4) courses:

         S 03(degrees) 40' 38" E, 137.16 feet to an iron pipe set marking the
         point of curvature of a nontangent curve to the left;

         224.74 feet along the arc of said curve having a radius of 862.05 feet
         and a chord bearing and chord of N 82(degrees) 39' 10" W, 224.10 feet
         respectively, to an iron pipe set;

         S 07(degrees) 10' 13" W, 61.29 feet to an iron pipe set and

         S 87(degrees) 37' 34" W, 300.45 feet

to an iron pipe set in the northerly right-of-way line of Woodland Park Road
(Route 7806), said point marking the point of curvature of a non-tangent curve
to the left;

thence with the said right-of-way line of Woodland Park Road

<PAGE>

         86.50 feet along the arc of said curve having a radius of 55.00 feet
         and a chord bearing and chord of S 88(degrees) 47' 10" W, 77.86 feet
         respectively,

to an iron pipe set marking the northeasterly corner of TST Woodland, L.L.C.;

thence departing said Woodland Park Road and with the northerly lines of said
TST Woodland, L.L.C. the following eight (8) courses:

         N 46(degrees) 16' 08" W, 45.22 feet to a point;

         S 53(degrees) 38' 47" W, 131.13 feet to a point;

         N 87(degrees) 14' 32" W, 405.49 feet to a point;

         N 65(degrees) 26' 08" W, 84.93 feet to a point;

         S 84(degrees) 34' 15" W, 175.57 feet to a point;

         S 29(degrees) 04' 19" W, 70.64 feet to a point;

         S 89(degrees) 27' 30" W, 84.90 feet to a point and

         N 53(degrees) 11' 58" W, 37.00 feet

to an iron pipe set in the aforementioned southeasterly right-of-way line of
Centreville Road marking the northwesterly corner of said TST Woodland, L.L.C.;

thence with the said right-of-way line of Centreville Road the following three
(3) courses:

         N 36(degrees) 48' 02" E, 334.78 feet to an iron pipe set;

         N 51(degrees) 13' 27" E, 52.19 feet to an iron pipe set and

         N 36(degrees) 47' 48" E, 352.70 feet

to the point of beginning.

Containing 497,009 square feet or 11.40976 acres of land.

<PAGE>

                                    EXHIBIT B
                                    ---------

                                   Definitions
                                   -----------

         "AAA": As defined in Section 34.2.

         "Abatement Notice": As defined in Section 7.4(b).

         "Above Building Standard Installations": As defined in Section 13.1.

         "Additional Base Building Requirements": As defined in Section 2.3(b).

         "Additional Rent": As defined in Article 1.

         "Adverse Event": As defined in Article 30.

         "Affiliate": An entity controlled by, controlling or under common
control with, either Landlord or Tenant, as the case may be (including, without
limitation, as to Tenant only, any Successor Corporation).

         "Agreed Area of the Building": As defined in Article 1.

         "Agreed Area of each Floor": As defined in Article 1.

         "Agreed Area of the Premises": As defined in Article 1.

         "Alterations": As defined in Section 5.1.

         "Approved Zoning" shall mean, collectively, the following: (i) the
Conceptual/Final Development Plan/Special Exception Plat prepared by William H.
Gordon Associates, Inc., consisting of five (5) sheets variously dated December
1999 through June 23, 2000; (ii) Site Plan 5518-SP-25; (iii) the Proffers; and
(iv) the Development Conditions.

         "Assessed Valuation": As defined in Section 8.1(a).

         "Association": Woodland Park Property Owners Association, Inc. and any
successor thereto.

         "Association Declaration": That certain Declaration of Covenants,
Conditions and Restrictions dated February 25, 1986 and recorded February 26,
1986 in book 6324 at page 0514 among the land records of Fairfax County,
Virginia, as may be amended from time to time.

<PAGE>

         "Base Rate": The annual rate of interest publicly announced from time
to time by Citibank, N.A., or its successor, in New York, New York as its "base
rate" (or such other term as may be used by Citibank, N.A., from time to time,
for the rate presently referred to as its "base rate").

         "Base Building": The Building to be constructed upon the Land in
accordance with the Base Building Construction Documents.

         "Base Building Construction Documents": As defined in Exhibit C.
                                                               ---------

         "Base Building Work":  As defined in Exhibit C.
                                              ---------

         "BOMA Standard": The 1996 edition of the Standard Method for Measuring
Floor Area in Office Buildings published by the Building Owners and Managers
Association (ANSI/BOMA Z65.1-1996).

         "Broker for Tenant":  As defined in Article 1.

         "Building":  As defined in Article 1.

         "Building Services":  As defined in Article 11.

         "Building Systems": The mechanical, electrical, plumbing, sanitary,
sprinkler, heating, ventilation and air conditioning, security, life-safety,
elevator and other service systems or facilities of the Base Building,
sprinklers and the horizontal distribution systems within and servicing the Base
Building and by which mechanical, electrical, plumbing, sanitary, heating,
ventilating and air conditioning, security, life-safety and other service
systems are distributed for provision of such services to the Base Building.

         "Business Days": All days, excluding Saturdays, Sundays and all days
observed by either the State in which the Building is located, or the Federal
Government.

         "Business Hours": Daily from 8:00 a.m. to 7:00 p.m., Saturdays 9:00
a.m. to 1:00 p.m., Sundays and Holidays excepted or, for as long as Tenant is
the sole tenant, such other hours as Tenant may elect.

         "Code": The Internal Revenue Code of 1986, as amended, and the
regulations promulgated thereunder.

         "Comparable Buildings":  As defined in Section 7.1.

         "Commencement Date":  As defined in Article 1.

                                      B-2

<PAGE>

         "Common Areas" : During any period in which the Building is
multi-tenanted, (i) all portions of the Land other than portions upon which the
Building is physically located, including all exterior parking areas (but
excluding the Parking Garage), drive ways, landscaped areas and the like, and
(ii) all loading docks, corridors, lobbies, elevator cabs, stairs, telephone
closets, electrical closets, janitorial closets, plenums, risers, core area
restrooms and other public portions of the Building (but the foregoing shall not
be construed to render any plenum, electrical or telecommunications closets on
any Floor leased solely to Tenant to constitute a Common Area). The foregoing
notwithstanding, during any period in which Tenant is leasing (A) 100% of the
Building, Tenant shall have the exclusive right to use the interior Common
Areas, and priority usage of the exterior Common Areas, and (B) 100% of any
Floor of the Building, Tenant shall have the exclusive right to use the interior
Common Areas on such Floor.

         "Communications Equipment": As defined in Section 3.1(c).

         "Competitors": As defined in Section 33.6.

         "Conditions Precedent": As defined in Section 37.

         "Construction Default": As defined in Section 19.2.

         "Construction Procedures": As defined in Section 5.2.

         "Control" (including the terms "controlled by" and "under common
                                         -------------       ------------
control with": The possession, directly or indirectly or as trustee or executor,
------------
of the power to direct or cause the direction of the management or policies of a
Person, whether through the ownership of stock or as trustee or executor, by
contract or credit arrangement or otherwise. For the purposes hereof, "control"
shall be deemed to also require ownership of not less than ten (10%) of the
voting stock or other beneficial interest of such corporation (or other entity).
Notwithstanding the foregoing, ownership of fifty-one percent (51%) or more of
the voting stock of such corporation shall be deemed control hereunder.

         "Decorative Alterations": As defined in Section 5.1.

         "Deficiency": The difference between (a) the Fixed Rent (including the
unamortized portion of the Supplemental Allowance) and Additional Rent for the
relevant period, and (b) the net amount, if any, of rents collected under any
reletting effected pursuant to the provisions of the Lease for any part of such
period (after first deducting from such rents all reasonable expenses incurred
by Landlord in connection with the termination of this Lease, Landlord's
re-entry upon the Premises and such reletting, including repossession costs,
brokerage commissions, attorneys' fees and disbursements, and alteration costs).

                                      B-3

<PAGE>

         "Design and Construction Agreement": The Design and Construction
Agreement of even date herewith attached hereto and incorporated herein as
Exhibit C.
---------

         "Development Conditions": As defined in Section 20.2.

         "Discretionary Expenses": All Operating Expenses except insurance
(cost, not scope, so long as the scope is consistent with other Tishman
properties in the area), labor contracts negotiated pursuant to collective
bargaining agreements (cost, not scope, so long as the scope is consistent with
other Tishman properties in the area), snow removal (as to cost only, but not
number of incidents), utility rates, expenditures incurred in respect of an
emergency, and costs of elevator, mechanical, electrical, maintenance and
life-safety contracts.

         "Environmental Laws": (i) the Comprehensive Environmental Response,
Compensation and Liability Act of 1980, as amended (42 U.S.C. Sections 9601 et
seq.), (ii) the Hazardous Materials Transportation Act, as amended (49 U.S.C.
Sections 1801 et seq.), (iii) the Resource Conservation and Recovery Act, as
amended (42 U.S.C. Sections 6901 et seq.) and the regulations adopted and
promulgated pursuant thereto, (iv) the Federal Water Pollution Control Act (33
U.S.C. Section 1251 et seq.), (v) the Clean Air Act (42 U.S.C. Section 7401 et
seq.), and the regulations adopted and promulgated pursuant thereto, (vi) any
other Federal, state or local environmental law, ordinance, rule, regulation
and/or other statute or order of a governmental authority relating to pollution
or protection of the environment, and (vii) any Federal, state or local law,
ordinance, rule, regulation and/or other statute or order of a governmental
authority relating to the protection, use or development for commercial purposes
of any "wetlands".

         "Environmental Liabilities": Any and all reasonable and necessary
costs, liabilities, damages and expenses (including reasonable attorneys fees
and court costs) incurred, suffered or sustained with respect to the presence,
removal, utilization, generation, storage, transportation, disposal or treatment
of any Hazardous Materials or any Hazardous Materials Release, including
cleanups, remedial and response actions, remedial investigations and feasibility
studies, and permits and licenses required by, or required to be undertaken in
order to comply with any Environmental Laws, as well as any damages for injury
to person, property or natural resources resulting from Hazardous Materials or
any Hazardous Materials Release, and claims of governmental agencies or third
parties for cleanup costs and costs of removal, discharge, and satisfaction of
all liens, encumbrances and restrictions on the Premises relating to the
foregoing.

         "Equipment": As defined in Section 5.6.

         "Estimate": As defined in Section 13.1.

         "Essential Service": As defined in Section 7.4(b).

                                      B-4

<PAGE>

         "Event of Default": As defined in Article 17.

         "Excess TI Costs": As defined in Section 2.2.

         "Expense Statement": As defined in Section 8.4(b).

         "Expiration Date": As defined in Article 1.

         "Extension Option": As defined in Section 31.1.

         "Final Completion": As to any construction performed in, on or about
the Premises, the Building or the Land, that such work shall have been completed
as certified by an architect selected by Tenant and an architect selected by
Landlord as being complete based on their reasonable professional judgments
using AIA standards. Without limitation, the Standard Base Building Work shall
not have achieved Final Completion until satisfaction of the following items:
satisfactory completion of Punch List Items and delivery to Tenant of all
warranties (per the specification), equipment and operations manuals, all
building materials to be stockpiled, lien releases from all contractors and
suppliers, "as built" drawings, HVAC commissioning and balancing reports,
evidence of compliance with the acoustical criteria for the curtain wall system,
and the existing elevator contractor with Otis Elevator made freely assignable
to Tenant or its designee.

         "Financial Condition": Shall mean satisfaction of the following test:
(1) tangible net worth (i.e., assets minus liabilities (in each case excluding
goodwill)) as of the end of the immediately preceding quarter of $400,000,000;
and (2) revenues for the preceding four quarters of not less than $500,000,000.

         "First Class Retailers": As defined in Section 20.7.

         "Extension Period Fixed Rent": As defined in Section 31.2(b)(i).

         "Extension Period": As defined in Section 31.1.

         "Extension Periods": As defined in Section 2.3(c).

         "FMR": As Defined in Section 31.2.

         "Fixed Rent": As defined in Article 1.

         "Floor": A full floor of the Building. The term "Floor" preceded by a
number shall mean the indicated floor of the Building.

         "Floor Ready Condition": As defined in Exhibit C.
                                                ---------

         "Foreclosure Date": As defined in Section 10.5(c).

                                      B-5

<PAGE>

         "GAAP": Generally accepted accounting principles, consistently applied.

         "Governmental Authority (Authorities)": The United States of America,
the Commonwealth of Virginia, the County of Fairfax, or any political
subdivision, agency, department, commission, board, bureau or instrumentality of
any of the foregoing, now existing or hereafter created, having jurisdiction
over the Premises or any portion thereof or the curbs, sidewalks, and areas
adjacent thereto.

         "Hazardous Materials": Any substances, materials or wastes currently or
in the future deemed or defined in any Requirement as "hazardous substances,"
"toxic substances," "contaminants," "pollutants" or words of similar import,
except for reasonable quantities of customary office, cleaning and cafeteria
supplies.

         "Hazardous Materials Release": Any release, spill, leak, pumping,
pouring, emitting, emptying, discharge, injection, escaping, leaching, dumping
or disposing into the environment (air, land or water) of any Hazardous
Materials.

         "Holidays" shall be: New Year's Day, Martin Luther King's Birthday,
Memorial Day, Independence Day, Labor Day, Veteran's Day, Thanksgiving Day, and
Christmas Day.

         "Incentives": As defined in Section 20.6.

         "Indemnitee": As to Landlord: Landlord, Landlord's Agent, each
Mortgagee and each Lessor, and each of their respective direct or indirect
partners, officers, shareholders, directors, members, trustees, beneficiaries,
employees, principals, contractors, licensees, invitees, servants, agents, or
representatives; and as to Tenant: Tenant and each of its direct or indirect
partners, officers, shareholders, directors, members, trustees, beneficiaries,
employees, principals, contractors, licensees, invitees, servants, agents or
representatives.

         "Initial Calendar Year": As defined in Section 8.4.

         "Initial Installations": As defined in Section 4.1.

         "Initial Term": As defined in Section 2.3(c)

         "Insured Parties": As defined in Section 12.1(c).

         "Interest Rate": As defined in Article 1.

         "Issuing Bank": As defined in Section 35.2.

         "Land": As defined in Article 1.

                                      B-6

<PAGE>

         "Landlord Affiliate": Any entity that is an Affiliate of Landlord.
Without limitation, the term "Landlord Affiliate" shall be deemed to include (i)
TST Woodland, L.L.C., a Delaware limited liability company (the "Declarant"),
(ii) Tishman Speyer Properties, L.P., a Delaware limited partnership, (iii)
Tishman Speyer Crown Equities, a Delaware general partnership, (iv) Tishman
Speyer Associates Limited Partnership, a New York limited partnership, and (v)
Tishman Speyer/Traveler's Real Estate Venture, L.P., a Delaware limited
partnership (the "Fund").

         "Landlord Delay": Any actual delay suffered by Tenant in the completion
of the Initial Installations to the extent caused by any negligence, misconduct
or unreasonable interference of, or any breach of this Lease by, Landlord and/or
Landlord's Agent or Affiliates.

         "Landlord's Agent":  As defined in Article 1.

         "Landlord's Agents": Landlord's agents, employees, contractors and
subcontractors and, solely while in the control of Landlord an invitee of
Landlord (but expressly excluding Tenant or Tenant's Agents).

         "Landlord's Contribution":  As defined in Article 1.

         "Landlord's FMR Proposal":  As defined in Section 31.3.

         "Last Rent Commencement Date":  As defined in Article 1.

         "Latent Defects": Any defect in design, materials or construction not
readily discernible upon a physical inspection of the Premises.

         "Lease Year": The period commencing on the Last Rent Commencement Date
and ending on the last day of the month which completes twelve (12) full
calendar months after the Last Rent Commencement Date, and each twelve (12)
month period thereafter commencing on the first (1st) day after the end of the
immediately preceding Lease Year, except that the last Lease Year shall end on
the last day of the Term.

         "Lender": As defined in Section 10.5.

         "Lessor": A lessor under a Superior Lease.

         "Letter of Credit": As defined in Section 35.2.

         "Lock-Out Allowance": As defined in Exhibit C, Paragraph C.2(g).

         "Lock-Out Date": As defined in Section 32.1(c).

         "Losses": As defined in Section 29.1(b).

                                      B-7

<PAGE>

         "Major Alterations":  As defined in Section 5.1.

         "Material Default": Shall mean (i) any Event of Default in the payment
of money, or (ii) any non-monetary Event of Default arising in relation to a
substantial or material obligation of Tenant under this Lease (as opposed to a
minor non-compliance with a non-monetary covenant, even where such
non-compliance extends past applicable cure periods hereunder). Without
limitation, a failure to comply with, or violation of, the following
non-monetary covenants shall be deemed to be material, and shall constitute
Material Defaults hereunder if the same continue after expiration of the
applicable cure period under this Lease: (A) any failure of Tenant to deliver
the Security Deposit as and when provided herein, or to replace or refresh the
Security Deposit as and where provided herein; (B) any failure of Tenant to
accept delivery of possession of the Premises (or any phase thereof) when
Substantial Completion thereof has occurred and tender of possession thereof is
made in accordance herewith; (C) any violation of the Permitted Uses provisions
of this Lease in more than de minimis ways; (D) any assignment or sublease made
in violation of the requirements of this Lease; (E) any violation by Tenant of
its environmental covenants under this Lease; (F) any failure by Tenant to
obtain insurance coverage required by this Lease; (G) any holdover by Tenant in
violation of this Lease; (H) any breach of Tenant's obligation to deliver
possession of the Premises to Landlord at the expiration or earlier termination
of the Term in the condition required herein; and (I) any material violation of
a Requirement required to be complied with by Tenant under this Lease.

         "Memorandum of Option": As defined in Article 39.

         "Mortgage(s)": Any mortgage, trust indenture or other financing
document which may now or hereafter affect the Premises, and all renewals,
extensions, supplements, amendments, modifications, consolidations and
replacements thereof or thereto, substitutions therefor, and advances made
thereunder.

         "Mortgagee(s)": Any mortgagee, trustee or other holder of a Mortgage.

         "Non-Disturbance Agreement": As defined in Section 10.5.

         "Non-Renewal Notice": As defined in Section 35.2.

         "Offer Notice": As defined in Section 32.2(a).

         "Offer Price": As defined in Section 32.2(a).

         "Operating Budget": As defined in Section 8.4(a).

         "Operating Expenses": As defined in Section 8.1(b).

         "Option Agreement": That certain Option Agreement dated as of even date
herewith by and between Landlord and Tenant.

                                      B-8

<PAGE>

         "Option Building": As defined in Article 1.

         "Option Land": As defined in Article 1.

         "Option Notice": As defined in Section 31.1.

         "Option Property": As defined in Article 1.

         "Order": As defined in Section 37.1.

         "Outside Date": As defined in Section 2.3(a)(1).

         "PSA": As defined in Section 32.1(c).

         "Parking Garage": As defined in Section 3.3.

         "Partial Renewal": As defined in Section 31.5.

         "Partial Term": The period (if any) commencing on the Commencement Date
and ending on the day immediately preceding the Last Rent Commencement Date.

         "Parties": As defined in Section 36.3.

         "Partners": As defined in Section 15.9.

         "Partnership Tenant": As defined in Section 15.8.

         "Pending Contract": As defined in Section 32.2(a).

         "Permitted Entity": As defined in Section 33.6.

         "Permitted Uses": As defined in Article 1.

         "Person": A natural person, a partnership, a limited liability company,
a corporation and any other form of business or legal association or entity.

         "Phase One": As defined in Section 2.3(b).

         "Phase Two": As defined in Section 2.3(b).

         "Phasing Plan": As defined in Section 2.4.

         "Plans and Specifications": The Base Building Construction Documents
and the Initial Installations Construction Documents, both as defined in the
Design and Construction Agreement attached Exhibit C.
                                           ---------

                                      B-9

<PAGE>

     "Policy": As defined in Section 12.1(c).

     "Premises": As defined in Article 1.

     "Primary Purchase Option": As defined in Section 32.1(a).

     "Proffers": As defined in Section 20.2.

     "Prohibited Use": Any use or occupancy of the Premises that would: (a)
cause unreasonable damage to the Building or any equipment, facilities or other
systems therein; (b) impair the exterior appearance of the Building in more than
a de minimis manner; (c) violate the certificate of occupancy issued for the
Building or (d) be inconsistent (in more than a de minimis manner) with the
Permitted Uses hereunder. "Prohibited Use" also includes the use of any part of
the Premises for: (i) a restaurant or bar (except for the use of in-house food
service and cafeteria purposes); (ii) the preparation, consumption, storage,
manufacture or sale of food, beverages, liquor, tobacco (except in connection
with vending machines and/or warming kitchens or a restaurant or cafeteria
installed for the use of employees or permitted occupants of the Premises only)
or drugs; (iii) the business of photocopying, multilith or offset printing
(except photocopying in connection with businesses of permitted occupants of the
Premises); (iv) a typing or stenography business; (v) a school or classroom
(except for the use of employees of permitted occupants of the Premises only);
(vi) lodging or sleeping; (vii) the operation of retail facilities (meaning a
business whose primary patronage arises from the generalized solicitation of the
general public to visit Tenant's offices in person without a prior appointment)
of a savings and loan association or retail facilities of any financial,
lending, securities brokerage or investment activity; (viii) a payroll office
(except for the use of employees of permitted occupants of the Premises only);
(ix) a barber, beauty or manicure shop; (x) an employment agency, executive
search firm or similar enterprise; (xi) offices of any Governmental Authority,
any foreign government, or any agency or department of the foregoing; (xii) the
manufacture, retail sale, storage of merchandise or auction of merchandise,
goods or property of any kind to the general public which could reasonably be
expected to create a volume of pedestrian traffic substantially in excess of
that normally encountered in the Premises; (xiii) the rendering of medical,
dental or other therapeutic or diagnostic services (except for the use of
employees of permitted occupants of the Premises only); or (xiv) any illegal
purposes or any activity constituting a nuisance.

     "Punch List Items": Items of construction which require correction or
completion due to one or more minor or insubstantial details of construction,
decoration, mechanical adjustment or installation, and that do not unreasonably
and adversely affect the use and occupancy of the Premises for the normal
conduct of Tenant's business and/or do not materially and adversely detract from
the overall aesthetic appearance of the Premises or the Building.

     "Purchase Notice": As defined in Section 32.1(b).

                                      B-10

<PAGE>

     "ROFOP": As defined in Section 32.2(a).

     "ROFOP PSA": As defined in Section 32.2(c).

     "Reduced Service": As defined in Section 11.1(b).

     "Reduction": As defined in Section 35.5(a).

     "Reduction Date": As defined in Section 35.5(a).

     "Reduction Schedule": As defined in Section 35.5(a).

     "Renewal Parameters": As defined in Section 31.2(b).

     "Rent": As defined in Article 1.

     "Rent Commencement Date": As defined in Article 1.

     "Requirements": All laws, rules, orders, ordinances, regulations, statutes,
requirements, codes and executive orders, extraordinary and ordinary of (i) all
Governmental Authorities, including the Americans With Disabilities Act, 42
U.S.C. ss. 12,101 (et seq.), and any law of like import, and all rules,
regulations and government orders with respect thereto, and any of the foregoing
relating to Hazardous Materials, environmental matters, public health and safety
matters, (ii) any applicable fire rating bureau or other body exercising similar
functions, affecting the Premises or the maintenance, use or occupation thereof,
or any street, avenue or sidewalk comprising a part of or in front thereof or
any vault in or under the same and (iii) all requirements of all insurance
bodies affecting the Premises which are customarily applicable to Comparable
Buildings.

     "Required Improvements": All improvements which are required to be
performed or made by Landlord pursuant to the Approved Zoning.

     "Rules and Regulations": The rules and regulations annexed to and made a
part of this Lease as Exhibit I, as they may be modified from time to time by
                      ---------
Landlord.

     "Secondary Financial Condition": Satisfaction of the following test: (1)
tangible net worth (i.e., assets minus liabilities (in each case excluding
goodwill)) as of the end of the immediately preceding quarter of $200,000,000;
and (2) revenues for the preceding four quarters of not less than $250,000,000.

     "Security Deposit": As defined in Article 1.

     "Senior Lienors": As defined in Section 10.5(a).

                                      B-11

<PAGE>

     "Special Offset Amounts": As defined in Section 19.2(b).

     "Specialty Alterations": Initial Installations and Alterations consisting
of the cafeteria (but not normal kitchens or executive bathrooms), computer
installations (other than raised floors), safe deposit boxes, vaults, reinforced
floors (unless there is no adverse effect (other than a de minimis effect) upon
adjacent floors and spaces), internal staircases, conveyors, dumbwaiters,
supplemental HVAC, generators, Communications Equipment and other Initial
Installations and Alterations of a similar character (but not cabling,
partitions, decorative Alterations and the like) which deviate from generic
improvements made to office space in Comparable Buildings.

     "Standard Base Building Work": As defined in Exhibit C.
                                                  ---------

     "Substantial Completion": As to any construction performed by any party in
the Premises, including the Base Building Work, Initial Installations, or any
Alterations, "Substantial Completion" or "Substantially Completed" means that
such work has been completed substantially in accordance with (a) the provisions
of this Lease and the Design and Construction Agreement applicable thereto, (b)
the plans and` specifications for such work, and (c) all applicable
Requirements, except for Punch List Items. With respect to the Standard Base
Building Work, "Substantial Completion" shall also include (i) the completion of
the Base Building substantially in accordance with the requirements specified in
Exhibit C, Schedule C-6 ("Building Shell Definition") as evidenced by the
---------  ------------
issuance of a certificate of substantial completion by Landlord's architect,
(ii) all Building Systems and equipment having been tested and operating, (iii)
all interior and exterior common and public-type areas (including telephone
trunk lines to the Building, mechanical rooms, electrical closets, and janitor
closets for the applicable Floor, the Building lobby, the elevator lobbies for
the applicable Floor, all public restrooms which are part of such Floor, and all
other common and public areas of floors to be occupied in such phase by Tenant)
(except for Punch List Items and long lead items therein, as aforesaid), being
completed to the extent necessary to permit construction of the Initial
Installations and occupancy, (iv) the receipt of a building shell
non-residential use permit for the Base Building, (v) completion of the items
specified in Exhibit C, Schedule C-7 ("Floor Ready Condition") for each Floor,
             ---------  ------------
and (vi) all exterior site improvements, including but not limited to the
Parking Garage, surface parking areas, landscaping and exterior utilities, have
been substantially completed and operational (subject to Punch List Items),
other than those items (including final landscaping installations) which are
reasonably deferred due to seasonal considerations or which are long-lead items
the delayed installation of which will not unreasonably and adversely affect the
ability of Tenant to make beneficial use of such improvements or the Premises
(or the applicable portion thereof).

     "Successor Corporation" shall mean: (A) any successor entity via a bona
fide merger, consolidation, business reorganization or sale of substantially all
of the assets or stock of VeriSign, Inc.; or (B) any entity which acquires all
or substantially all of the

                                      B-12

<PAGE>

assets or stock of Tenant by merger, consolidation, acquisition or other
business reorganization.

     "Super Outside Date": As defined in Section 2.3(a)(1).

     "Superior Lease(s)": Any ground or underlying lease of the Land or any part
thereof heretofore or hereafter made by Landlord and all renewals, extensions,
supplements, amendments, modifications, consolidations, and replacements
thereof.

     "Supplemental Allowance": As defined in Section 2.2.

     "Surrender Term": As defined in Section 2.3.

     "Taxes": As defined in Section 8.1.

     "Tenant Affiliate": any entity that is an Affiliate of Tenant.

     "Tenant Delay": Any actual delay suffered by Landlord in the completion of
the Base Building Work to the extent caused by any negligence, misconduct or
unreasonable interference of, or any breach of this Lease by, Tenant and/or
Tenant's Agents.

     "Tenant's Agents": Tenant's agents, employees, contractors, subcontractors,
sublessees, licensees and, solely while on the roof of the Building or within
the Building and under Tenant's control, invitees and business visitors (but
expressly excluding Landlord and Landlord's Agents).

     "Tenant's Notice": As defined in Section 15.2.

     "Tenant's Operating Expense Payment": As defined in Section 8.4.

     "Tenant's Parking Allocation": As defined in Section 3.3(a).

     "Tenant's Proportionate Share": As defined in Article 1.

     "Tenant's Property": Tenant's movable fixtures and movable partitions,
telephone and other equipment, computer systems, trade fixtures, furniture,
furnishings, and other items of personal property which are removable without
material damage to the Premises or Building.

     "Term": As defined in Article 1.

     "Threshold": As defined in Section 15.1(a)(i).

     "Transfer": As defined in Section 36.2.

                                      B-13

<PAGE>

     "Unavoidable Delays": The inability of either Landlord or Tenant to fulfill
or delay in fulfilling any of its obligations under this Lease expressly or
impliedly to be performed by such Person or such Person's inability to make or
delay in making any repairs, additions, alterations, improvements or decorations
or such Person's inability to supply or delay in supplying any equipment or
fixtures, if such Person's inability or delay is due to or arises by reason of
strikes, labor troubles or by accident, or by any cause whatsoever reasonably
beyond such Person's control and is not caused by such Person's negligence or
willful misconduct, except that lack of funds shall not be deemed a cause beyond
the reasonable control of either Landlord or Tenant.

     "Woodland Park": The property generally known as Woodland Park and
consisting, as of the date of this Lease, of approximately 170 acres located in
Fairfax County, Virginia, as shown on Exhibit J.
                                      ---------

                                      B-14

<PAGE>

                                    EXHIBIT C

                        Design and Construction Agreement
                        ---------------------------------

                                (Attached hereto)

<PAGE>

                                    EXHIBIT D
                                    ---------

                               Fixed Rent Schedule
                               -------------------

<TABLE>
<CAPTION>
Lease Year   Annual Fixed Rental Rate/rsf   Annual Fixed Rent   Monthly Fixed Rent
----------   ----------------------------   -----------------   ------------------
<S>          <C>                            <C>                 <C>
    1                  $21.00                 $8,497,965.00         $708,163.75
    2                  $21.74                 $8,795,393.78         $732,949.48
    3                  $22.50                 $9,103,232.56         $758,602.71
    4                  $23.28                 $9,421,845.70         $785,153.81
    5                  $24.10                 $9,751,610.30         $812,634.19
    6                  $24.94                 $10,092,916.66        $841,076.39
    7                  $25.81                 $10,446,168.74        $870,514.06
    8                  $26.72                 $10,811,784.65        $900,982.05
    9                  $27.65                 $11,190,197.11        $932,516.43
    10                 $28.62                 $11,581,854.01        $965,154.50
    11                 $29.62                 $11,987,218.90        $998,934.91
</TABLE>

Extension Period #1          See Section 31
Extension Period #2          See Section 31
Extension Period #3          See Section 31

     NOTE: Monthly Fixed Rent for the period prior to the beginning of Lease
Year #1 (which Lease Year begins only on the Last Rent Commencement Date) shall
be calculated at the same per square foot annual rental rate provided for Lease
Year #1 (i.e., $21.00 p.s.f.), and shall be determined for each month during
such period by multiplying such annual rental rate by the number of square feet
of the Premises for which a Rent Commencement Date has occurred, and dividing
the product so obtained by 12.

     NOTE: If applicable, the Fixed Rent stated above shall be modified to
include amounts required to be amortized into Fixed Rent in accordance with the
provisions of Section 2.2 of the Lease, if any (which amounts shall be
separately stated so as to not be subject to any annual escalation as above
provided). The parties agree to execute an amendment to this Lease which
specifies the amount of additional Fixed Rent that will become applicable by
operation of such provision within a reasonable time after such calculation is
made.

     NOTE: Fixed Rental Rate escalation factor is 3.5% per annum.

<PAGE>

                                    EXHIBIT E
                                    ---------

             Subordination, Non-Disturbance and Attornment Agreement
             -------------------------------------------------------

     No form SNDA shall be attached. Any SNDA to be signed in the future shall
be in compliance in all material respects with Section 10.5 of the Lease.

<PAGE>

                                    EXHIBIT F
                                    ---------

                             Cleaning Specifications
                             -----------------------

CONTRACTOR RESPONSIBILITIES
---------------------------

I.   GENERAL CLEANING.

         A. DAILY.
            -----

               a. Vacuum carpeted areas and rugs, moving light furniture, other
         than desks, file cabinets, etc.

               b. Empty and clean wastepaper baskets, ash trays, receptacles,
         etc.; damp dust as necessary. All cardboard, paper, and cans will be
         recycled and placed in appropriate dumpsters located in loading dock.

               c. Clean cigarette urns and replace sand or water, as necessary.

               d. Remove wastepaper and waste materials to a designated area in
         the building, using special janitorial carriages. Waste or rubbish bags
         shall be standardized to accommodate a uniform trash bag, whenever
         possible.

               e. Dust baseboards, chair rails, trim louvers, pictures, charts,
         etc. within reach.

               f. Wash drinking fountains and coolers.

               g. Keep janitorial room in clean and orderly condition.

         B. WEEKLY.
            ------

               a. Dust and wipe clean furniture, fixtures, desk equipment,
         telephones, and window sills with specially treated cloths.

II.  LAVATORIES/TOILET ROOMS, EXECUTIVE BATHROOMS AND KITCHENS.

         A. DAILY.
            -----

               a. Sweep and mop flooring with approved germicidal detergent
         solution.

               b. Wash and polish mirrors, shelves, bright work, etc., including
         flushometers, piping, and toilet seat hinges.

               c. Wash both sides of toilet seats, basins and bowls, and urinals
         using a brush with an approved germicidal detergent solution.

<PAGE>

               d. Dust partitions.

               e. Wash tile walls, dispensers, and receptacles.

               f. Empty and clean towel and sanitary disposal receptacles.

               g. Remove wastepaper and refuse to designated area in the
         building, using special janitorial carriages, approved by Agent.

               h. Fill toilet tissue, soap (with first quality liquid soap),
         hand lotion dispensers, sanitary napkin, seat covers and towel
         dispensers with supplies furnished by Service Contractor as approved by
         Manager.

               i. Toilet bowl brush shall be used on toilet bowls and care shall
         be given to clean flush holes under rim of bowls and passage traps.
         Bowl Cleaner shall be used at least once a month and more often, if
         necessary.

               j. Flush floor drains with water at least once a week.

The intent of this specification is that toilet rooms shall be maintained in a
clean and odor free condition upon completion of nightly cleanup. It is
understood that in the kitchen, pantries, and coffee bars, Service Contractor
will have no obligation to wash dishes or other utensils unless stipulated
within or by a separate side agreement.

III.   ENTRANCE LOBBY.

         B. DAILY.
            -----

               a. Sweep and damp marble flooring. Wipe down columns with a damp
                  cloth.

               b. Directory board glass is to be cleaned with a glass cleaner.

               c. Clean building entrance glass door with a glass cleaner and
                  wipe down chrome handles and trim with a dry cloth.

               d. Vacuum entrance floor mats.

               e. Clean all cigarette urn(s) and wipe down chrome lids. Replace
                  sand, as necessary.

               f. Floor in elevator cabs will be vacuumed and properly

                  maintained. If carpet is stained, remove soluble spots which
                  can safely respond to standard spotting procedure without risk
                  of injury to color or fabric.

               g. Dust and rub down elevator doors, walls, metal work, and
                  saddles in elevator cabs.

<PAGE>

               h. Dust walls up to twelve feet, and keep free from finger marks,
                  smudges, etc.

IV.  OFFICE AREAS.

          A. DAILY.
             -----

               a. Elevator, office and utility doors on each floor will be
                  checked for general cleanliness, removing finger marks, as
                  necessary.

               b. Remove finger marks from metal partitions, glass and wood
                  doors and partitions, and other similar surfaces, as necessary
                  and practical.

               c. Wipe clean interior building metal, as necessary and
                  practical.

               d. Dust window sills.

          B. MONTHLY.
             -------

               a. Unoccupied finished areas shall be swept or vacuumed, if
                  carpeted.

               b. All grille, ceiling, and wall area around air conditioning and
                  return air grilles will be cleaned, in place, once each month
                  or more often, if necessary.

               c. Dust Venetian blinds.

          C. QUARTERLY.
             ---------

               a. Dust pictures, frames, charts, graphs, and similar wall
                  hangings not reached in nightly cleaning.

               b. Dust vertical surfaces such as partitions, ventilating
                  louvers, etc., not reached in nightly cleaning.

          D. ANNUALLY.
             --------

               a. Dust and clean electric fixtures and any other fittings in
                  public corridors as necessary.

V.   LAVATORIES, SHOWERS, EXECUTIVE BATHROOMS, KITCHEN AND PANTRIES.

          A. MONTHLY.

               a. Machine scrub flooring with approved germicidal detergent
                  solution, as necessary.

<PAGE>

               b. Wash partitions, tile walls, and enamel surfaces with approved
                  germicidal detergent solution.

               c. Dust exterior of lighting fixtures.

               d. Do high dusting.

VI.  FLOOR MAINTENANCE.

          A. WEEKLY.

               a. Buff composition flooring once a week. (strip quarterly and
                  apply three (3) coats of approved finish). This specification
                  includes common area and tenant areas.

          B. AS NEEDED BASIS.
             ---------------

               a. Spot cleaning of carpeting in elevator lobbies and corridors,
                  as needed, to remove soluble spots which safely respond to
                  standard spotting procedures without risk or injury to color
                  of fabric.

               b. Resilient tile flooring shall be maintained in a waxed,
                  polished, scrub free condition at all times. Wherever floors
                  require wet mopping, it is essential that they be left in a
                  streak free condition.

               c. Contractor shall use a low alkaline, non-injurious detergent
                  for floor maintenance.

               d. Contractor shall use approved floor finishes that are
                  non-staining and provide a high degree of slip prevention.

               e. Contractor shall wash and wipe baseboards during the floor
                  maintenance operation.

VII. PUBLIC AREAS.

          A. DAILY.
             -----

               a. Elevator stainless steel to be washed using neutral cleaner
                  and polished dry with soft white terry cloth.

               b. Restroom stainless steel washed with neutral cleaner and
                  polished dry with a soft white terry cloth.

          B. WEEKLY.
             ------

               a. Restroom floors and walls around urinals will be scrubbed.

<PAGE>

          C. MONTHLY.
             -------

               a. Restroom floors to be scrubbed.

          D. QUARTERLY.
             ---------

               a. Machine marble granite lobby floor with an approved cleaning
                  agent.

          E. OTHER.
             -----

               a. Remove current residual was from granite lobby floor (one
                  time).

VIII.  TENANT AREAS.

          A. DAILY.
             -----

               a. Marble flooring will be dust mopped and spot mopped.

               b. Carpeting will be spot cleaned daily using plain cold water
                  and a clean white terry cloth rag.

               c. Partition glass will be spot cleaned daily.

               d. All glass doors off of elevator lobby will be cleaned daily
                  with a glass cleaner.

          B. WEEKLY.
             ------

               a. Office areas with wood flooring will be buffed using a 18"
                  floor machine with a soft white buffing pad.

               b. Etched glass will be dusted only, using an artificial
                  lambswool duster.

NOTE: It is understood that, from time to time during the term of this
Agreement, Owner may request Service Contractor to perform services or provide
materials which are not set forth in the Contract Duties but are related to the
services encompassed within the Contract Duties (herein "Additional Work").
Service Contractor hereby agrees to perform such Additional Work so long as
prior to the performance of such Additional Work, Owner shall authorize in
writing the scope of such Additional Work and compensation payable, if any, to
Service Contractor for the full performance of said Additional Work.

<PAGE>

                                    EXHIBIT G
                                    ---------

                                Letter of Credit
                                ----------------

                                      DRAFT

DATE:  __________, 2001

IRREVOCABLE STANDBY LETTER OF CREDIT NUMBER:  _______

BENEFICIARY                         APPLICANT

TST WATERVIEW I, L.L.C.             VERISIGN, INC.
c/o Tishman Speyer Properties, L.P. [ADDRESS]
520 Madison Avenue
New York, New York  10022
Attn:  Chief Legal Officer

                                               AMOUNT
                                               US $14,000,000
                                               FOURTEEN MILLION AND 00/100 US
DOLLARS

                                        EXPIRATION ____________ ___, 2002 AT OUR
                                        COUNTERS

WE HEREBY ESTABLISH THIS IRREVOCABLE STANDBY LETTER OF CREDIT IN YOUR FAVOR
WHICH IS AVAILABLE BY PAYMENT WITH BANK OF AMERICA N.A., 333 S. BEAUDRY AVE.
19TH FLOOR, LOS ANGELES, CA 90017, UPON PRESENTATION OF YOUR DRAFTS AT SIGHT,
ACCOMPANIED BY:

BENEFICIARY'S SIGNED STATEMENT CERTIFYING THAT PURSUANT TO THE LEASE DATED AS OF
___________, 2001 BY AND BETWEEN TST WATERVIEW I, L.L.C., A DELAWARE LIMITED
LIABILITY COMPANY ("LANDLORD") AND VERISIGN, INC., A DELAWARE CORPORATION
("TENANT"), (THE "LEASE") THE LANDLORD IS PERMITTED TO DRAW UPON THE LETTER OF
CREDIT UNDER THE EXPRESS TERMS OF THE LEASE AND SETTING FORTH THE AMOUNT THAT
LANDLORD IS PERMITTED TO DRAW IN CONNECTION THEREWITH.

PARTIAL AND MULTIPLE DRAWINGS ARE PERMITTED.

IT IS A CONDITION OF THIS LETTER OF CREDIT THAT IT SHALL BE AUTOMATICALLY
EXTENDED FOR ADDITIONAL PERIODS OF ONE YEAR FROM THE PRESENT AND EACH SUCCESSIVE
EXPIRATION DATE HEREOF, UNLESS AT LEAST SIXTY (60) DAYS PRIOR TO THE THEN
CURRENT EXPIRATION DATE, WE SHALL NOTIFY YOU IN WRITING SENT BY
OVERNIGHT COURIER [OPEN FOR BofA REVIEW: TO THE ADDRESS SET FORTH ABOVE,

<PAGE>

WITH A COPY OF SUCH NOTICE TO TST WATERVIEW I, L.L.C., c/o Tishman Speyer
Properties, L.P., 520 Madison Avenue, New York, New York 10022, attn: Chief
financial officer] THAT WE ELECT NOT TO RENEW THIS LETTER OF CREDIT FOR SUCH
ADDITIONAL ONE YEAR PERIOD. UPON RECEIPT BY YOU OF SUCH NOTICE YOU MAY DRAW
HEREUNDER BY MEANS OF YOUR DRAFT ON US AT SIGHT, ACCOMPANIED BY YOUR WRITTEN
STATEMENT THAT YOU HAVE NOT RECEIVED AN APPROPRIATE RENEWAL OR REPLACEMENT OF
THIS LETTER OF CREDIT.

THIS LETTER OF CREDIT IS TRANSFERABLE. TRANSFER OF THIS LETTER OF CREDIT MAY BE
EFFECTED UPON PRESENTATION TO US OF THIS ORIGINAL LETTER OF CREDIT, A TRANSFER
REQUEST IN THE FORM OF EXHIBIT A ATTACHED HERETO AND PAYMENT OF OUR TRANSFER
                       ---------
FEE.

ALL DRAFTS DRAWN UNDER THIS CREDIT MUST BEAR ON THEIR FACE THE CLAUSE "DRAWN
UNDER [ISSUING BANK] LETTER OF CREDIT NO. __________ DATED ________, 200__."

EXCEPT SO FAR AS OTHERWISE EXPRESSLY STATED, THIS CREDIT IS SUBJECT TO THE
UNIFORM CUSTOMS AND PRACTICE FOR DOCUMENTARY CREDIT (1993 REVISION)
INTERNATIONAL CHAMBER OF COMMERCE, PUBLICATION NO. 500.

WE HEREBY AGREE WITH THE BENEFICIARY THAT DRAFTS DRAWN IN COMPLIANCE WITH THE
TERMS AND CONDITIONS OF THIS LETTER OF CREDIT, THAT THE SAME WILL BE DULY
HONORED UPON PRESENTATION TO US.

________________________________                  ______________________________
AUTHORIZED SIGNATURE                              AUTHORIZED SIGNATURE

                                      G-2

<PAGE>

                                    EXHIBIT A
                                    ---------

             REQUEST FOR ENTIRE ABSOLUTE AND IRREVOCABLE TRANSFER OF
                LETTER OF CREDIT WITHOUT SUBSTITUTION OF INVOICES

_______________________________________             ____________________, 200___
NAME

_______________________________________             LETTER OF CREDIT NO.________
ADDRESS

ISSUED BY ____________________________

TO:  BANK OF AMERICA, N.A.

WE REQUEST YOU TO TRANSFER ALL OF OUR RIGHTS AS BENEFICIARY UNDER THE LETTER OF
CREDIT REFERENCED ABOVE TO THE NEW BENEFICIARY NAMED BELOW, WHO IS THE SUCCESSOR
IN INTEREST UNDER THE LEASE REFERRED TO IN THE LETTER OF CREDIT:

_______________________________________
NAME OF NEW BENEFICIARY

_______________________________________
ADDRESS

BY THIS TRANSFER, ALL OUR RIGHTS AS THE ORIGINAL BENEFICIARY, INCLUDING ALL
RIGHTS TO MAKE DRAWINGS UNDER THE LETTER OF CREDIT, GO TO THE NEW BENEFICIARY.
THE NEW BENEFICIARY SHALL HAVE SOLE RIGHTS AS BENEFICIARY, WHETHER EXISTING NOW
OR IN THE FUTURE, INCLUDING SOLE RIGHTS TO AGREE TO ANY AMENDMENTS, INCLUDING
INCREASES OR EXTENSIONS OR OTHER CHANGES. ALL AMENDMENTS WILL BE SENT DIRECTLY
TO THE NEW BENEFICIARY WITHOUT THE NECESSITY OF CONSENT BY OR NOTICE TO US.

WE ENCLOSE THE ORIGINAL LETTER OF CREDIT AND ANY AMENDMENTS. PLEASE INDICATE
YOUR ACCEPTANCE OF OUR REQUEST FOR THE TRANSFER BY ENDORSING THE LETTER OF
CREDIT AND SEND IT TO THE NEW BENEFICIARY WITH YOUR CUSTOMARY NOTICE OF
TRANSFER.

FOR YOUR TRANSFER FEE:

____     ENCLOSED IS OUR CHECK FOR $___________ (NOT TO EXCEED $1,000)

____     YOU MAY DEBIT MY/OUR ACCOUNT NO.  ____________________

                                      G-3

<PAGE>

[OPEN FOR BofA REVIEW: DELETE THE FOLLOWING? WE ALSO AGREE TO PAY YOU ON DEMAND
ANY EXPENSES WHICH MAY BE INCURRED BY YOU IN CONNECTION WITH THIS TRANSFER.]

THE SIGNATURE AND TITLE AT THE RIGHT CONFORM WITH THOSE SHOWN IN OUR FILES AS
AUTHORIZED TO SIGN FOR THE BENEFICIARY. POLICIES GOVERNING SIGNATURE
AUTHORIZATION AS REQUIRED FOR WITHDRAWALS FROM CUSTOMER ACCOUNTS SHALL ALSO BE
APPLIED TO THE AUTHORIZATION OF SIGNATURES ON THIS FORM.

___________________________________
NAME OF BANK

___________________________________
AUTHORIZED SIGNATURE

                                      _________________________________________
                                            NAME OF BENEFICIARY

                                      _________________________________________
                                            NAME OF AUTHORIZED SIGNER AND TITLE

                                      _________________________________________
                                            AUTHORIZED SIGNATURE

                                      G-4

<PAGE>

                                    EXHIBIT H
                                    ---------

                                   [Reserved]
                                   ----------

<PAGE>

                                    EXHIBIT I
                                    ---------

                              Rules and Regulations
                              ---------------------

         The following rules and regulations have been formulated for the safety
and well-being of all the tenants of the Building (but only if more than one)
and become effective upon occupancy. Any repeated or continuing violation of
these rules and regulations by Tenant after the applicable notice and cure
period provided for in the Lease for non-monetary defaults shall constitute an
Event of Default under the Lease. To the extent of any conflict between these
rules and regulations, and the provisions of the Lease to which they are
attached, the provisions of the Lease shall be controlling. The rules and
regulations shall not be enforced by Landlord in a manner which is
discriminatory towards Tenant. The rules and regulations set forth herein may be
modified as provided in the Lease.

         1.  The sidewalks, entrances, passages, courts, vestibules, or
stairways, or other parts of the Building not occupied by any tenant shall not
be unreasonably obstructed or encumbered by any tenant or used for any purpose
other than ingress and egress to and from any tenant's Premises. Subject to
compliance with applicable requirements of the Design and Construction
Agreement, Landlord hereby consents to Tenant's installation and use of a
reasonable outdoor seating area in the vicinity of its cafeteria. Landlord
shall have the right to control and operate the public portions of the Building,
and the facilities furnished for the common use of the tenants, in such manner
as Landlord deems best for the benefit of the tenants generally. No tenant shall
knowingly permit the visit to its Premises of persons in such numbers or under
such conditions as to unreasonably interfere with the use and enjoyment by other
tenants of the entrances, and other public portions or facilities of the
Building.

         2.  Except as otherwise provided for in the Lease, no signs, awnings or
other projections shall be attached to the outside walls of any building without
the prior written consent of Landlord. No draperies, blinds, shades or screens
shall be attached to or hung in, or used in connection with, any window or door
of the Premises, without the prior consent of Landlord, which consent shall not
be unreasonably withheld, conditioned or delayed. Such signs, awnings,
projections, curtains, blinds, screens or other fixtures must be of a quality,
type, design and color, and attached in the manner reasonably approved by
Landlord.

         3.  No show cases or other articles shall be put in front of or affixed
to any part of the exterior of the Building, nor placed in any interior Common
Area of a multi-tenanted floor without the prior written consent of Landlord.

         4.  The water and wash closets and other plumbing fixtures shall not be
used for any purpose other than those for which they were constructed, and no
sweepings, rubbish, rags, or other substances shall be thrown therein.

<PAGE>

         5.  Except as provided in the Lease, there shall be no marking,
painting, drilling into or in any way defacing any part of the Premises or the
Building. Except in connection with a permitted security system, no tenant shall
construct, maintain, use or operate on the outside of the Building, any
electrical devices, wiring or apparatus in connection with a loud speaker system
or other sound system.

         6.  No animals, birds, pets of any kind shall be brought into or kept
in or about the Premises.

         7.  Other than in the cafeteria or any other restaurant space or
kitchen space within the Building, if any, no cooking shall be done or permitted
by any tenant on its Premises except for a tenant's employee's own use.
Microwave cooking devices, toasters, coffee machines, refrigerators, and other
similar kitchen or pantry devices typical of a general office use shall be
permissible. No tenant shall cause or permit any unusual or objectionable odors
to be produced or permeate from its Premises.

         8.  Any person employed by any tenant to do janitorial work within its
premises must, while in the Building and outside of the Premises, comply with
all instructions issued by the superintendent of the Building.

         9.  No tenant shall purchase spring water, ice, coffee, tea, soft
drinks, towels, or other like service, from any company or persons whose
repeated documented violations of these Regulations have caused, in Landlord's
reasonable opinion, a hazard or nuisance to the Building and/or its occupants,
and regarding which Landlord has notified Tenant in writing.

         10. Landlord reserves the right to exclude from the Building at all
times any person who does not properly identify himself to the Building
management.

         11. The Premises shall not be used for lodging or sleeping or for any
illegal purpose.

         12. No tenant shall occupy or permit any portion of its Premises to be
used or occupied for the manufacture, or sale of liquor, narcotics, tobacco in
any form.

         13. Canvassing, soliciting, and peddling on the Premises is prohibited
and each tenant shall  cooperate to prevent the same.

         14. There shall not be used in any space, or in the public halls of the
Building, either by any tenant or by jobbers or others in the delivery or
receipt of merchandise, any hand trucks, except those reasonably equipped (e.g.,
with rubber tires or side guards or similar protection) to protect the flooring
and walls of the applicable area.

                                      I-2

<PAGE>

                                    EXHIBIT J
                                    ---------

                          Description of Woodland Park
                          ----------------------------

Woodland Park is best loosely depicted as the property bound by Centreville Road
(Route 657) to the west, the Dulles Airport and Access Road (Route 267) to the
north, Monroe Street (Route 666) to the east and Sunrise Valley Drive (Route
5320) and Fox Mill Road (Route 665) to the south. The property consists of
approximately 168.6 acres.

Fairfax County tax map designations for the parcels encumbered by the covenants
include:

        .    16-3 ((1)) 29A
        .    16-3 ((1)) 29B
        .    16-3 ((1)) 29C
        .    16-3 ((1)) 29D
        .    16-3 ((11)) 1
        .    16-3 ((11)) 2
        .    16-3 ((11)) 3
        .    16-3 ((11)) 4B
        .    16-3 ((11)) 5A
        .    16-3 ((11)) 6A1
        .    16-3 ((11)) 6B
        .    16-3 ((11)) 6C
        .    16-3 ((11)) 6D
        .    16-3 ((11)) 7
        .    16-4 ((1)) 35
        .    16-4 ((1)) 36
        .    16-4 ((1)) 37
        .    16-4 ((1)) 38
        .    16-4 ((1)) 39

Although not included with the above referenced parcels, a pond providing
storm-water management and water quality for a portion of the Woodland Park
properties is located within the Southside development (tax map # 16-3 ((1))
25D) and obligations exist for the maintenance of this facility.

<PAGE>

                                    EXHIBIT K
                                    ---------

                             Construction Procedures
                             -----------------------

          The following covenants shall apply to any Landlord's work at the
Premises:

               A.  All contractor(s) shall be obligated to keep all construction
areas reasonably clean and free of trash and debris, and each party shall
monitor the activities of its contractors, subcontractors and their respective
employees with regard to keeping the Building clean. Any construction contract
entered into by Landlord for work to be performed in the Agreed Area of the
Premises shall indemnify Tenant from damages, losses and expenses associated
with the acts and omissions of the contractor, its agents, employees and
subcontractors, and shall otherwise be consistent with the terms hereof.

               B.  Landlord agrees to comply (or to cause its contractors to
comply) with all applicable federal, state and local laws, regulations and
ordinances in the performance of any work, and to promptly rectify any
violations of such laws caused by the acts or omission of Landlord, its
employees, agents and/or contractors.

               C.  The following covenants shall apply during the hours of
8:30 a.m. to 6:00 p.m. on weekdays when Tenant is occupying and conducting
business in any portion of the Building and Landlord is performing any of
Landlord's work or other work or repairs in the Building. Tenant acknowledges
that all such activities which are prohibited during such hours will be
scheduled at off-hours. All contracts for Landlord's work shall include these
covenants.

          1.   Landlord shall not permit the following activities;

               a.  Noise that is disruptive to Tenant;

               b.  Any and all core drilling on any floor directly contiguous to
any part of the Agreed Area of the Premises;

               c.  Work on bare concrete floors on a floor directly above
                   occupied tenant space that causes noise which is disruptive
                   to the Tenant in their occupied space;

               d.  Sweating or welding that causes objectionable odors; and/or

               e.  Painting or other activity that causes noxious fumes or odors
that may disrupt the Tenant

          2.   Landlord shall be responsible for maintaining the cleanliness of
               the elevator cabs and floors and shall use appropriate measures
               to protect floor coverings when moving equipment across carpet
               and in Common Areas.

<PAGE>

          3.   Landlord shall cause contractors and related personnel to remove
               their trash and debris daily (including waste foods and
               containers), or as often as necessary to maintain cleanliness in
               the Building and shall cause contractors and related personnel to
               use only the trash receptacles supplied by the contractors
               themselves. Building trash containers shall not be used for
               construction debris. Tenant shall have the right to bill Landlord
               for all cost incurred in cleaning and removing debris left by
               contractors or related personnel (only after appropriate
               notification and lack of reasonable response from Landlord).

          4.   Landlord will notify Tenant of all work schedules of all workers
               working within the Agreed Area of the Premises and the names of
               those who will be working in the Agreed Area of the Premises
               after Normal Business Hours. Landlord shall cause contractors and
               personnel to use loading dock area for all deliveries and will
               not use loading dock for vehicle parking. Landlord shall not
               permit contractors or related personnel to use Tenant's Parking
               Allocation without Tenant's consent, which shall not be
               unreasonably withheld, conditioned or delayed.

          5.   No building materials are to enter the Building by way of the
               lobby or be stored in the lobby or other public areas (unless
               there is no other physical way to bring such items into the
               Building, in which case such entry shall be coordinated with the
               Tenant).

          6.   Landlord shall not permit  construction  personnel to eat or
               congregate in the lobby, Common Areas or in front of the
               Building.

          7.   Landlord shall cause public spaces (i.e. elevators, bathrooms,
               lobby), to be protected and cleaned immediately after use by the
               contractors and related personnel. Tenant may remove construction
               debris or materials found in public areas and Landlord shall
               reimburse Tenant for the cost of such removal within (within the
               same time frames as Tenant's timing of payment of excess costs)
               business days of Tenant's written request therefor (only after
               appropriate notification and lack of reasonable response from
               Landlord).

          8.   Landlord shall institute rules prohibiting contractors or related
               personnel from possessing or consuming any alcohol or controlled
               substances in the Building.

          9.   The contractors and Landlord shall be responsible for all loss of
               any materials and tools owned by such contractors or Landlord and
               shall hold Tenant harmless for such loss and from any damages or
               claims resulting from such loss (unless an employee, contractor
               or visitor of the Tenant is adjudged to have participated in
               causing such loss or damages).

          10.  Landlord shall use its best efforts to avoid disturbing Tenant's
               normal operations.

<PAGE>

                                    EXHIBIT L
                                    ---------

           Specifications for HVAC, Electrical Capacity and Floor Load
           -----------------------------------------------------------

            See Exhibit C-6 to the Design and Construction Agreement.

<PAGE>

                                    EXHIBIT M
                                    ---------

                    Description of Waterview at Woodland Park
                    -----------------------------------------

Beginning at an iron pipe set marking the intersection of the southeasterly
right-of-way line of Centreville Road (Route 657) and the southerly right-of-way
line of the Dulles Access and Toll Road (Route 267);

thence with said right-of-way line of the Dulles Access and Toll Road, the
following five (5) courses:

         S 69(degrees) 43' 30" E, 135.89 feet to an iron pipe found

         S 72(degrees) 21' 11" E, 275.02 feet to an iron pipe set

         S 69(degrees) 04' 14" E, 434.33 feet to an iron pipe set;

         S 79(degrees) 08' 10" E, 255.41 feet to an iron pipe set marking the
         point of curvature of a non-tangent curve to the left and

         48.14 feet along the arc of said curve having a radius of 8,794.40 feet
         and a chord bearing and chord of S68(degree) 28' 07" E, 48.14 feet
         respectively,

to an iron pipe set marking the most northerly corner of now or formerly
National Rural Utilities Cooperative Finance Corporation;

thence departing said Dulles Access and Toll Road and with the northerly lines
of said National Rural Utilities Cooperative Finance Corporation the following
four (4) courses:

         S 03(degrees) 40' 38" E, 137.16 feet to an iron pipe set marking the
         point of curvature of a nontangent curve to the left;

         224.74 feet along the arc of said curve having a radius of 862.05 feet
         and a chord bearing and chord of N 82(degree) 39' 10" W, 224.10 feet
         respectively, to an iron pipe set;

         S 07(degrees) 10' 13" W, 61.29 feet to an iron pipe set and

         S 87(degrees) 37' 34" W, 300.45 feet

to an iron pipe set in the northerly right-of-way line of Woodland Park Road
(Route 7806), said point marking the point of curvature of a non-tangent curve
to the left;

thence with the said right-of-way line of Woodland Park Road the following ten
(10) courses:

<PAGE>

         163.72 feet along the arc of said curve having a radius of 55.00 feet
         and a chord bearing and chord of S 48(degrees) 33' 45" W, 109.63 feet
         respectively, to an iron pipe found marking the point of reverse
         curvature of a curve to the right;

         20.32 feet along the arc of said curve having a radius of 25.00 feet
         and a chord bearing and chord of S 13(degrees) 25' 55" E, 19.76 feet
         respectively, to an iron pipe found;

         S 09(degrees) 51' 07" W, 101.91 feet to an iron pipe found marking the
         point of curvature of a curve to the right;

         651.94 feet along the arc of said curve having a radius of 490.00 feet
         and a chord bearing and chord of S 47(degrees) 58' 04" W, 604.91 feet
         respectively, to an iron pipe found marking the point of compound
         curvature of a second curve to the right;

         477.14 feet along the arc of said curve having a radius of 963.95 feet
         and a chord bearing and chord of N 79(degrees) 44' 10" W, 472.28 feet
         respectively, to an iron pipe found marking the point of compound
         curvature of a third curve to the right;

         131.09 feet along the arc of said curve having a radius of 450.00 feet
         and a chord bearing and chord of N 57(degrees) 12' 37" W, 130.63 feet
         respectively, to an iron pipe set marking the point of reverse
         curvature of a curve to the left;

         62.31 feet along the arc of said curve having a radius of 691.62 feet
         and chord bearing and chord of N 51(degrees) 26' 45" W, 62.29 feet
         respectively, to an iron pipe set marking the point of reverse
         curvature of a curve to the right;

         14.56 feet along the arc of said curve having a radius of 948.95 feet
         and a chord bearing and chord of N 53(degrees) 35' 15" W, 14.56 feet
         respectively, to an iron pipe set and

         N 53(degrees) 08' 53" W, 36.40 feet

to an iron pipe found marking the point of curvature of a 45.00 foot radius
return to the right at the northeasterly intersection of aforementioned
Centreville Road and Woodland Park Road;

thence departing from Woodland Park Road and

         72.52 feet along the arc of said return having a chord bearing and
         chord of N 06(degrees) 58' 40" W, 64.93 feet respectively,

to an iron pipe set in the aforementioned southeasterly right-of-way line of
Centreville Road;

thence with the said right-of-way line of Centreville Road the following three
(3) courses:

         N 36(degrees) 48' 02" E, 616.21 feet to an iron pipe set;

<PAGE>

         N 51(degrees) 13' 27" E, 52.19 feet to an iron pipe set and

         N 36(degrees) 47' 48" E, 352.70 feet

to the point of beginning.

Containing 1,017,474 square feet or 23.35799 acres of land.

<PAGE>

                                    EXHIBIT N
                         AGREED AREAS OF FLOORS/PREMISES
<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------------------------------------------------
 ---------------------------------------------               --------------------------------------------------
   WATERVIEW                                                              TISHMAN SPEYER PROPERTIES
 ---------------------------------------------               --------------------------------------------------
 A DEVELOPMENT OF:                                                          SQUARE FOOTAGE SUMMARY
   TISHMAN-SPEYER                                                           ANSI/BOMA Z65.1-1996
 ---------------------------------------------    ---------  --------------------------------------------------
                    INSIDE       NON    BUILDING    FLOOR       BUILDING                   FLOOR     SINGLE      SINGLE
       FLOOR        GROSS     RENTABLE   COMMON    RENTABLE     COMMON        NET         RENTABLE   TENANT      TENANT
                    AREA      SERVICE   SERVICE   SERVICE       FACTOR      RENTABLE      SERVICE    USEABLE     FACTOR
 <S>               <C>        <C>       <C>       <C>        <C>            <C>           <C>       <C>          <C>
         1         32072.00    1251.20  7656.50    23164.30     1.037792     24039.72      2030.90   21133.40    1.137523
         2         32121.00    3058.20             29062.80     1.037792     30161.13      1905.00   27157.80    1.110588
         3         32121.00    1420.80             30700.20     1.037792     31860.41      1900.50   28799.70    1.106276
         4         32121.00    1420.80             30700.20     1.037792     31860.41      1900.50   28799.70    1.106276
         5         32121.00    1420.80             30700.20     1.037792     31860.41      1900.50   28799.70    1.106276
         6         32121.00    1420.80             30700.20     1.037792     31860.41      1900.50   28799.70    1.106276
         7         32121.00    1420.80             30700.20     1.037792     31860.41      1900.50   28799.70    1.106276
         8         32121.00    1420.80             30700.20     1.037792     31860.41      1900.50   28799.70    1.106276
         9         32121.00    1420.80             30700.20     1.037792     31860.41      1900.50   28799.70    1.106276
        10         32121.00    1420.80             30700.20     1.037792     31860.41      1900.50   28799.70    1.106276
        11         32121.00    1420.80             30700.20     1.037792     31860.41      1900.50   28799.70    1.106276
        12         32121.00    1420.80             30700.20     1.037792     31860.41      1900.50   28799.70    1.106276
        13         32121.00    1420.80             30700.20     1.037792     31860.41      1900.50   28799.70    1.106276
     PENTHOUSE      7474.00     393.90  7079.60        0.00     1.037792         0.00         0.00       0.00    0.000000

   TOTAL          424998.00   20332.10 14736.10   389929.30                 404665.40     24841.40  365087.90

<CAPTION>

    -------------------------------------
              DATE: 18 JUN 2001
    -------------------------------------
            PRINT DATE: 18 JUN 2001
             FILE: Waterview BOMA
    -------------------------------------
    FLOOR     MULTIPLE    MULTIPLE
   COMMON     TENANT      TENANT
   SERVICE    USEABLE     FACTOR
   <S>       <C>          <C>
      79.30   21054.10     1.141807
    1399.10   25758.70     1.170911
    1316.10   27483.60     1.159252
    1316.10   27483.60     1.159252
    1316.10   27483.60     1.159252
    1316.10   27483.60     1.159252
    1316.10   27483.60     1.159252
    1316.10   27483.60     1.159252
    1316.10   27483.60     1.159252
    1316.10   27483.60     1.159252
    1316.10   27483.60     1.159252
    1316.10   27483.60     1.159252
    1316.10   27483.60     1.159252
       0.00       0.00     0.000000

   15955.50  349132.40
------------------------------------------------------------------------------------------------------------------------------------
</TABLE>

<TABLE>
<CAPTION>
   ------------------------------------        -------------------------------           -----------------------------------
   NON RENTABLE                                BUILDING COMMON                           RENTABLE SERVICE
   ------------------------------------        -------------------------------           -----------------------------------
<S>                                            <C>                                       <C>
   FLOOR 1                                     FLOOR 1                                   FLOOR 1

   STAIRS                       334.40         EL./FR./REAR LOBBY          3640.80       TELEPHONE CLOSET             36.20
   ELEVATORS                    916.80         HALL                          37.00       MECHANICAL ROOM             680.50
                                               SECURITY/RECEPTION           167.10       ELECTRICAL ROOM             268.60
   TOTAL                       1251.20         PUMP ROOM                    465.30       RESTROOMS                   998.70
   ------------------------------------
                                               MAIN TEL. ROOM               122.20       JANITOR                      46.90
   FLOOR 2                                     MAIN ELEC. ROOM              597.10
                                               FIRE CONTROL                  69.90       TOTAL                      2030.90
                                                                                         -----------------------------------
   STAIRS                       334.40         FREIGHT ELEV./LOBBY          144.90
   ELEVATORS                    915.70         SERV.CORR./LOADING DOCK     1112.00       FLOOR 2
   SHAFTS                       234.20         PROP. MAN. OFF.             1300.20
   ATRIUM                      1573.90                                                   TELEPHONE CLOSET             36.20

                                                                                         MECHANICAL ROOM             605.30

   TOTAL                       3058.20         TOTAL                       7656.50       RESTROOMS                   992.20
   ------------------------------------        ------------------------------------
                                                                                         ELECTRICAL ROOM             225.50
   FLOOR 3-13                                  PENTHOUSE                                 JANITOR                      45.80

   STAIRS                       334.40         BLDG. MAINTENANCE           7079.60       TOTAL                      1905.00
                                                                                         -----------------------------------
   ELEVATORS                    852.20

   SHAFTS                       234.20                                                   FLOORS 3-13

   TOTAL                       1420.80                                                   TELEPHONE CLOSET             36.20
   ------------------------------------
                                               TOTAL                       7079.60       MECHANICAL ROOM             602.70
                                               ------------------------------------
   PENTHOUSE                                                                             RESTROOMS                   992.20
                                                                                         ELECTRICAL ROOM             223.60
   STAIRS                       393.90                                                   JANITOR                      45.80

                                                                                         TOTAL                      1900.50
                                                                                         -----------------------------------
   TOTAL                        393.90
   ------------------------------------

<CAPTION>

 -----------------------------------
 FLOOR COMMON
 -----------------------------------
<S>                         <C>

 FLOOR 1

 CORRIDOR                     79.30

 TOTAL                        79.30
 -----------------------------------

 FLOOR 2
 CORRIDOR                     59.00

 ELE. LOB./CORRIDOR         1196.20
 FREIGHT ELE. LOBBY          143.90

 TOTAL                      1399.10
 -----------------------------------

 FLOORS 3-13

 CORRIDOR                     59.50
 ELE. LOB./CORRIDOR         1111.30
 FREIGHT ELE. LOBBY          145.30

 TOTAL                      1316.10
 -----------------------------------
</TABLE>

<PAGE>

                                    EXHIBIT O
                                    ---------

                           Form of Memorandum of Lease
                           ---------------------------

                                   (attached)

<PAGE>

                                    EXHIBIT P
                                    ---------

                       Form of Purchase and Sale Agreement
                       -----------------------------------

                                   (attached)

<PAGE>

                                    EXHIBIT Q
                                    ---------

                            Form of Option Agreement
                            ------------------------

                                   (attached)

<PAGE>

                                    EXHIBIT R
                                    ---------

                                Declarant Letter
                                ----------------

                                   (attached)

<PAGE>

                                    EXHIBIT S
                                    ---------

                                   [Reserved]

<PAGE>

                                    EXHIBIT T
                                    ---------

                                Form of ROFO PSA
                                ----------------

         Landlord will prepare a purchase and sale agreement based on then
current market conditions for an arm's length sale transaction between seller
and purchaser which will give consideration to the fact that the purchaser is a
major tenant of the park, and which will attempt in good faith to accommodate
Tenant's reasonable requests regarding synthetic lease or other off balance
sheet financing considerations. The parties will negotiate in good faith to
arrive at a mutually acceptable agreement within thirty (30) days.

<PAGE>

                                    EXHIBIT U
                                    ---------

                          SAMPLE AMORTIZATION SCHEDULE
                          ----------------------------

                                [To be attached]

<PAGE>

                                    EXHIBIT V
                                    ---------

                              LOCATION OF GENERATOR
                              ---------------------

<PAGE>

                                    EXHIBIT W
                                    ---------

                       LOCATION OF ENTRANCE MONUMENT SIGN
                       ----------------------------------

<PAGE>

                                    EXHIBIT X
                                    ---------

                      SCHEDULE FOR COMPLETION OF PROFFERS/
                      ------------------------------------
                             DEVELOPMENT CONDITIONS
                             ----------------------

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------------------------------------------------------
  To be completed
   not later than
    Substantial                                                   Transportation                            Site
  Completion of:                Traffic                         Management (I.B.5)                        Amenities
  --------------                -------                         ------------------                        ---------
--------------------------------------------------------------------------------------------------------------------------------
<S>                 <C>                                <C>                                    <C>
  Waterview I       . Traffic signal at Centreville    $ Construction of bus shelters, if     $ Benches and outdoor eating
                      Road and Woodland Park Drive       required by Governmental               areas in plazas and landscaped
                      (I.B.1.d) (deadline is July 1,     Authorities, shall be an ongoing       open space. (I.C.4.b)
                      2002, notwithstanding anything     obligation of Landlord.
                      herein to the contrary)                                                 $ Eight-foot trail along
                                                                                                Centreville Road frontage
                                                                                                (I.C.5.a)

                                                                                              $ Bicycle parking facilities.
                                                                                                (cond. #8)

                                                                                              $ Showers/lockers in one of
                                                                                                the buildings (cond. #8)
                                                                                                Landlord to satisfy proffer;
                                                                                                however, if the County requires
                                                                                                public access to the showers,
                                                                                                the showers satisfying such
                                                                                                proffers shall not be located
                                                                                                in Waterview I.

                                                                                              $ Interior noise level DNL 50 dBA
                                                                                                or less (cond. #10)

                                                                                              . Lighting-full cutoff at Property
                                                                                                perimeter (I.B.6 and cond. #9)
--------------------------------------------------------------------------------------------------------------------------------
</TABLE>

        ________________
        * Regardless of notations to the contrary on a site plan or other
        -
        documentation regarding the Proffers, the terms of this chart shall
        control as between Landlord and Tenant.

<PAGE>

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------------------------------------------------------
  To be completed
   not later than
    Substantial                                                   Transportation                            Site
  Completion of:                Traffic                         Management (I.B.5)                        Amenities
  --------------                -------                         ------------------                        ---------
--------------------------------------------------------------------------------------------------------------------------------
<S>                 <C>                                <C>                                    <C>
  Waterview II      $ Traffic signal at Sunrise        . Construction of bus shelters, if     $  Sidewalks along Woodland Park
                      Valley Drive and Wood Oak          required by Governmental                Drive and within interior of
                      Drive (I.B.3)                      Authorities, shall be an                Waterview. (I.B.5.b) (cond. #5)
                                                         ongoing obligation of Landlord.

                    $ Tenant shall have a one-time
                      right to request that Landlord                                          $  If not already satisfied,
                      perform a warrant study, if                                                Showers/lockers in one of the
                      not required by VDOT or Fairfax                                            buildings (cond. #8) Landlord
                      County, for traffic signal at                                              to satisfy proffer;  however,
                      Sunrise Valley Drive and Wood                                              if the County requires public
                      Oak Drive and Landlord will be                                             access to the showers, the
                      obligated to construct such                                                showers satisfying such proffers
                      traffic signal, if warranted                                               shall not be located in Waterview
                                                                                                 I.

                    $ Four-lane approach to the
                      Centreville Road and Woodland
                      Park Drive intersection (along
                      Woodland Park Road frontage)
                      (I.B.2)

                      -  Dual left turn lanes onto
                         southbound Centreville Road

                      -  Either dual right turn lanes
                         onto northbound Centreville
                         Road or dedicated right turn
                         lane and shared right
                         turn/through lane, as determined
                         by VDOT
--------------------------------------------------------------------------------------------------------------------------------
</TABLE>

<PAGE>

<TABLE>
<CAPTION>
---------------------------------------------------------------------------------------------------------------------------------
  To be completed
   not later than
    Substantial                                                   Transportation                            Site
  Completion of:                Traffic                         Management (I.B.5)                        Amenities
  --------------                -------                         ------------------                        ---------
---------------------------------------------------------------------------------------------------------------------------------
<S>                 <C>                                <C>                                    <C>
Waterview III       . Second left turn lane from       . Construction of bus shelters,        . Paved and landscaped plaza areas
                      southbound Centreville Road        if required by Governmental            between three buildings and the
                      onto Woodland Park Drive           Authorities, shall be an               park. (I.C.4.a)
                      (I.B.1.c)                          ongoing obligation of Landlord.

                    . If not previously constructed,                                          $ If not already satisfied,
                      Tenant shall have a one-time                                              Showers/lockers in one of the
                      right to request that Landlord,                                           buildings (cond. #8) Landlord
                      if not previously required by                                             to satisfy proffer; however, if
                      VDOT or Fairfax County, perform                                           the County requires public
                      a warrant study for traffic                                               access to the showers, the
                      signal at Sunrise Valley Drive                                            showers satisfying such proffers
                      and Wood Oak Drive and Landlord                                           shall not be located in Waterview
                      will be obligated to construct                                            I.
                      such traffic signal, if
                      warranted
---------------------------------------------------------------------------------------------------------------------------------
</TABLE>

<PAGE>

                                    EXHIBIT Y
                                    ---------

                      SIGN SPECIFICATIONS FOR WOODLAND PARK
                      -------------------------------------

                    Woodland Park Property Owners Association

                           Building Signage Standards

                                   April 2000

Tenant Building Mounted Signs

1.       Size. Shall be determined by the allowable area per Fairfax County
         ----
         code. Buildings with single tenants shall be able to  use the
         allowable square footage provided the size is appropriate to certain
         guidelines, i.e., the size of spandrel and/or parapet and its
         relationship to length and height of the proposed sign.

         This standard is arbitrary and approval will be determined on a case by
         case basis. In no event shall any one sign exceed 100 square feet and a
         total of only two signs will be allowed. Multi-tenant building signage
         shall be addressed on a case by case basis as allowed for in their
         respective lease.

2.       Type. Signs shall be backlit, mounted on pins attached to the facade
         ----
         with anchor bolts.

         Examples include the Sprint sign at Northridge I, the Road Runner sign
         at Northridge II, and the Computer Associates sign at 2291 Wood Oak
         Drive.

Building Monument Signs

1.       Size. Shall be determined by the allowable area per Fairfax County
         ----
         code.

         Building monument signs for buildings with single tenants shall conform
         to the Park signage standards.

         Building monument signs for multi-tenant buildings shall also conform
         to the Park signage standards and shall be addressed on a case by case
         basis as allowed for in their respective lease.

         This standard will not be compromised.

<PAGE>

                                    EXHIBIT Z
                                    ---------

                      CONDITIONS LANDLORD MUST SATISFY FOR
                        ISSUANCE OF TENANT'S TITLE POLICY
                        ---------------------------------

Please see attached. In addition, Landlord must satisfy any other requirements
reasonably requested by Title Company relating to agreements or other documents
that are recorded against the Property or entered into by Landlord that encumber
the Property between the date hereof and the satisfaction of the Conditions
Precedent set forth in Section 37.1 of the Lease.

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00031-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00031-of-00352.parquet"}]]