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                                                                   Exhibit 10(h)

               CONSOLIDATED, AMENDED AND RESTATED DEED OF LEASE


     THIS CONSOLIDATED, AMENDED AND RESTATED DEED OF LEASE is made and entered
into as of the 12 day of November, 1997, effective for all purposes as of the
1st day of January, 1997, by and between (i) HMCE ASSOCIATES LIMITED
PARTNERSHIP, R.L.L.P., a Virginia registered limited partnership, successor in
interest to HB Limited Partnership, successor in interest to HMCE  Associates
Limited Partnership (hereinafter re(Pounds)erred to as "Landlord"), and (ii) ICF
KAISER HUNTERS BRANCH LEASING, INC., a Delaware corporation, successor in
interest to American Capital & Research Corporation (hereinafter referred to as
"Tenant"), and referred to by singular pronouns of the neuter gender, regardless
of the number and gender of the parties involved.

     WHEREAS, the Landlord and Tenant are parties to a certain Lease Agreement
dated April 27, 1988 (the "Lease"), pursuant to which Landlord leased to Tenant
certain office space containing approximately 105,057 square feet of net
rentable area in the office building known as "Hunter's Branch - Phase I,
Building 2" located in Fairfax, Virginia (the "Building"); and

     WHEREAS, Landlord and Tenant entered into a First Amendment to Lease
Agreement dated July 29, 1988 (the "First Amendment"), which modified a
component of the rent payable under the Lease; and

     WHEREAS, Landlord and Tenant entered into a Second Amendment to Lease
Agreement dated February 12, 1990 (the "Second Amendment"), which modified
certain provisions of the Lease relating to Basic Rent and Operating Expense
Increases; and

     WHEREAS, Landlord and Tenant entered into a Third Amendment to Lease
Agreement dated December 22, 1992 (the "Third Amendment"), whereby Tenant
surrendered 167 rentable square feet of the leased premises to Landlord; and

     WHEREAS, Landlord and Tenant now desire to consolidate, amend and restate
the Lease, the First Amendment, the Second Amendment and the Third Amendment in
this Consolidated, Amended and Restated Lease Agreement..

     NOW, THEREFORE, in consideration of the mutual promises hereinafter set
forth and other good and valuable consideration, the receipt and sufficiency of
which are hereby acknowledged, Landlord hereby leases to Tenant, and Tenant
hereby leases from Landlord, the Leased Premises, for the Term (as defined
below), except that Landlord reserves and Tenant shall have no right in and to
(a) the use of the exterior faces of all perimeter walls of the Building, (b)
except as otherwise provided in subsections (d) and (e) of Section 10, the use
of the roof of the Building, or (c) the use of the air space above the Building.

     1.   Definitions.

          (a) General Interpretive Principles.  For purposes of this Lease,
except as otherwise expressly provided or unless the context otherwise requires,
(i) the terms defined in this Section have the meanings assigned to them in this
Section and include the plural as well as the singular, and the use of any
gender herein shall be deemed to include the other genders; (ii) accounting
terms not otherwise defined herein have the meanings assigned to them in
accordance with generally accepted accounting principles; (iii) references
herein to "Sections," "subsections," "paragraphs" and other subdivisions without
reference to a document are to designated Sections, subsections, paragraphs and
other subdivisions of this Lease; (iv) a reference to a sub-section without
further reference to a Section is a reference to such subsection as contained in
the same Section in which the reference appears, and this rule shall also apply
to paragraphs and other subdivisions; (v) the words "herein," "hereof,"
"hereunder" and other words of similar import refer to this Lease as a whole and
not to any particular provision; and (vi) the word "including" means "including,
but not limited to"; and (vii) a reference to an Exhibit without further
reference to another document is a reference to such Exhibit as an Exhibit to
this Lease.
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          (b) Special Lease Definitions.  As used in this Lease the following
words and phrases shall have the meanings indicated:

          Basic Rent:  For each Lease Year, an amount equal to the product
obtained by multiplying the Rentable Area of the Leased Premises by the Rent per
Square Foot for such Lease Year.

          Building: The office building known as 9302 Lee Highway, Fairfax,
Virginia 22031, on the land described in Exhibit A to this Lease, including
Tenant's non-exclusive right in and to the parking deck and Landlord's leasehold
estate in the underlying land.

          Building Rentable Area: 200,071 square feet, being the total net
rentable area of the Building consisting of Office Space..

          Comparison Month:  The calendar month of March.

          CPI:  The Consumer Price Index for All Urban Consumers (CPI-U) -- All
Items (1982-84 = 100) for the Washington, DC - MD - VA metropolitan area
currently prepared by the Bureau of Labor Statistics of the United States
Department of Labor and published bi-monthly.  If, during the Term, the CPI
ceases to be published, then Landlord and Tenant shall mutually agree upon a
substitute index, it being understood and agreed that such substitute index
shall be similar index generally recognized as authoritative, and the parties
shall reconcile the base thereof with the base of the CPI.  If the parties
cannot agree upon a substitute index, then the matter shall be submitted to
arbitration under the rules of the American Arbitration Association.

          First Rental Period: As defined in (S)4.2(b) of the Ground Lease.

          Inflation Adjustment:  For the sixth Lease Year (i.e. commencing
November 1, 2003) and each Lease Year thereafter during the Term (including any
Renewal Period), the lesser of (i) 2.5% of the Rent per Square Foot for the
immediately preceding Lease Year or (ii) 225% of the percentage (if any) by
which (x) the CPI for the Comparison Month in the immediately preceding Lease
Year exceeds (y) the CPI for the Comparison Month in 1998.  Exhibit C contains
an illustration of the operation of the Inflation Adjustment.

          Initial Term: The period commencing on the Lease Commencement Date and
ending on October 31, 2012, but in any event the Initial Term shall end on any
date when this Lease is sooner terminated pursuant to its terms.

          Land: The land described in Exhibit A.

          Landlord's Notice Address:  1355 Piccard Drive, Suite 470, Rockville,
Maryland 20850.

          Lease Commencement Date:  January 1, 1997.

          Leased Premises:  The space containing 104,890 square feet of Rentable
Area, consisting of the part of the First Floor outlined on the floor plans of
the Building attached hereto as Exhibit B, the entire Second through Sixth
Floors inclusive, and the Penthouse.

          Leasing Broker:  The Carey Winston Company, which broker shall be paid
by Tenant.

          Office Park:  The project consisting of the Building, the office
building known as 9300 Lee Highway, Fairfax, Virginia 22031, and the common
areas and facilities serving both such buildings.

          Office Space: The portion of the Building consisting of the First
through Twelfth Floors, inclusive.

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          Operating Expense Base: The quotient obtained by dividing (i)
$1,086,869.00, by (ii) the Building Rentable Area.

          Operating Expense Commencement Date: January 1, 1998.

          Operating Expense Increases: For the calendar year in which the
Operating Expense Commencement Date occurs and each calendar year thereafter
during the Term, an amount equal to Tenant's Proportionate Share of the excess
of Landlord's Operating Expenses for such calendar year over the product
obtained by multiplying the Operating Expense Base by the Building Rentable
Area.

          Renewal Period:  The additional period of five years for which Tenant
is permitted to extend the Initial Term of this Lease pursuant to Section 30.

          Rent Commencement Date: January l, 1997.

          Rent per Square Foot:  $23.16 during the period from January 1, 1997
through November 11, 1997 (i.e., total Basic Rent for such period shall be
$2,096,478.10).  $23.64 for the period from November 12, 1997 through December
31, 1997, and for each of the second, third, fourth and fifth Lease Years (i.e.,
Basic Rent for such period shall be $2,479,599.60 per Lease Year).  For the
sixth Lease Year, the Rent per Square Foot shall be an amount equal to $23.16,
increased by the Inflation Adjustment for the sixth Lease Year.  For the seventh
Lease Year, and for each Lease Year thereafter during the Term, the Rent per
Square Foot shall be an amount equal to the Rent per Square Foot for the
immediately preceding Lease Year, increased by the Inflation Adjustment for the
Lease Year for which the computation is being made.  The foregoing amounts are
net of the cost of electricity for the Leased Premises, which shall be billed to
and paid by Tenant.

          Rentable Area: The net rentable area (in square feet) of all or any
part of the Leased Premises from time to time.  The net rentable area of the
Leased Premises is agreed to be 104,890 square feet.

          Second Rental Period: As defined in (S)4.2(c) of the Ground Lease.

          Security Deposit: $125,000.

          Storage Space: The area, containing approximately 5,855 square feet of
Rentable Area, located in the Penthouse, which is shown on the floor plans
attached as Exhibit B to this Lease.

          Tenant's Notice Address: 9300 Lee Highway, Fairfax, Virginia 22031-
1207, Attn: Lease Administrator, with a copy to the same address, Attn: General
Counsel.

          Tenant's Proportionate Share: The percentage from time to time which
the Rentable Area of the portion of the Leased Premises consisting of Office
Space is of the Building Rentable Area, which percentage is acknowledged and
agreed to be forty-nine and one-half percent (49.5%) as of the date of this
Lease.

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                                                                         Exhibit
          Term: The Initial Term and the Renewal Period, if any, as to which
Tenant shall have effectively exercised its right to extend, but in any event
the Term shall end on any date when this Lease is sooner terminated pursuant to
the terms hereof.

          (c) General Definitions.  As used in this Lease the following words
and phrases shall have the meanings indicated:

          Additional Charges: All amounts payable by Tenant to Landlord under
this Lease other than Basic Rent.  All Additional Charges shall be deemed to be
additional rent and all remedies applicable to the non-payment of Basic Rent
shall be applicable thereto.

          Alterations: As defined in Section 9(a).

          Business Days: All days except Saturdays, Sundays and the following
legal holidays: New Years Day, Memorial Day, Fourth of July, Labor Day,
Thanksgiving Day and Christmas Day.

          Default Interest Rate: A rate per annum equal to the lesser of (a) the
sum of (i) the base rate of interest from time to time established and publicly
announced by NationsBank, N.A., Washington, D.C., in its sole discretion, as its
then-applicable base rate of interest to be used in determining actual interest
rates to be charged to certain of its borrowers, said base rate to change from
time to time as and when the change is announced as being effective, and (ii)
two percent (2%), or (b) ten percent (10%) per annum.

          Event of Default: Any of the events set forth in Section 16(a) as an
event of default.

          Floor: A floor of the Building located above the foundation slab or
above an area below grade level which is designated as a basement or cellar.
The term "Floor" preceded by a number shall mean the indicated floor of the
Building.

          Ground Lease: The Lease Agreement dated November 3, 1987, between The
First Union National Bank of Virginia, as Trustee, as successor by merger to
First American Bank of Virginia, Trustee, as lessor, and Landlord, as lessee,
pursuant to which Landlord leases the land described in Exhibit A to this Lease.

          Landlord: The landlord named herein or any subsequent owner or lessee,
from time to time, of the Landlord's interest in the Building.

          Lease: This Deed of Lease, as amended from time to time, and all
Exhibits attached hereto.

          Lease Year: The period of 12 months commencing on the Lease
Commencement Date and ending on the last day of the month which completes 12
full calendar months after the Lease Commencement Date, and each 12 month period
thereafter commencing on the first 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.

          Legal Requirements:  All laws, statutes, ordinances, orders, rules,
regulations and requirements of all federal, state and municipal governments,
and the appropriate agencies, officers, departments, boards and commissions
thereof, and the board of fire underwriters and/or the fire insurance rating
organization or similar  organization performing the same or similar functions,
whether now or hereafter in force, applicable to the Building or any part
thereof and/or the Leased Premises, and notices from Landlord's Mortgagee, as to
the manner of use or occupancy or the maintenance, repair or condition of the
Leased Premises and/or the Building, and the usual and customary requirements of
the carriers of all fire insurance policies maintained by Landlord on the
Building.

          Mortgage: Any mortgage, deed of trust or other security instrument of
record creating an interest in or affecting title to the Building or the land on
which it is constructed, or both, or any part thereof, including a


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leasehold mortgage or subleasehold mortgage, and any and all renewals,
modifications, consolidations, or extensions of any such instrument; Mortgagee
shall mean the holder or beneficiary of any Mortgage.

          Operating Expenses: The aggregate of all costs and expenses reasonably
and customarily paid or incurred on an accrual basis by Landlord in connection
with the management, operation, servicing and maintenance of the Leased
Premises, the Building, the Building parking facility and the land on which the
Building is constructed including, but not limited to, employees' wages,
salaries, welfare and pension benefits and other fringe benefits; payroll taxes;
Real Estate Taxes; the Net Annual Rental payable by Landlord under (and as
defined in) the Ground Lease; electricity charges for the main lobby, service
areas and other common areas of the Building and the operation of the Building
elevators; telephone service; painting of public or other common areas of the
Building; exterminating service; detection and security services; trash removal;
sewer and water charges; premiums for fire and casualty, liability, rent,
workers' compensation, sprinkler, water damage and other insurance; repairs and
maintenance to the Building; building, janitorial and cleaning supplies;
uniforms and dry cleaning; snow removal; landscaping maintenance; window
cleaning; service contracts for the maintenance of elevators, boilers, HVAC and
other mechanical, plumbing and electrical equipment; legal fees (other than
legal fees relating to the negotiation of leases with present or prospective
tenants of the Building or the enforcement of Landlord's rights under leases
with tenants for space in the Building); accounting fees; advertising;
management fees of four percent (4%) of gross Building rents (exclusive of
Operating Expense payments), whether or not paid to any Person having an
interest in or under common ownership with Landlord; one-half of all costs and
expenses of providing the shuttle bus services required by Section 31 (reduced
by all amounts received by Landlord or its affiliates for after- hours shuttle
bus service); dues and assessments to any property owners' association in which
the Building is a member; window glass replacement, repair and cleaning; repair
and maintenance of the grounds, including costs of landscaping, gardening and
planting; service contracts with independent contractors, including but not
limited to security and energy management service contractors; compensation
(including employment taxes, fringe benefits, salaries, wages, medical, surgical
and general welfare benefits [including health, accident and group life
insurance]) for all personnel employed by Landlord or its property management
company who perform duties in connection with the operation, management,
maintenance and repair of the Building (in each case, allocated among all
properties served by such employees on a reasonable basis, if such employees are
utilized by more than one property), including a proportionate share of the
salary and benefits of the property manager assigned to the Building, based upon
the number of properties served by such property manager, but in no event more
than one-fourth (1/4) of such salary and benefits; and all other expenses now or
hereafter reasonably and customarily incurred in connection with the operation,
maintenance, and management of first class office buildings in the Tysons Corner
area of Northern Virginia.  If Landlord makes an expenditure for a capital
improvement to the Building to reduce Operating Expenses or to comply with Legal
Requirements not in effect at the time the Building was constructed, and if,
under generally accepted accounting principles, such expenditure is not a
current expense, the cost thereof shall be amortized over a period equal to the
useful life of such improvements, determined in accordance with generally
accepted accounting principles, and the amortized cost allocated to each
calendar year during the Term shall be treated as an Operating Expense.  Except
as provided in the preceding sentence, capital expenditures, depreciation and
amortization shall not be included in Operating Expenses.  Refunds of Real
Estate Taxes (reduced by Landlord's reasonable expenses in obtaining such
refunds), amounts received by Landlord from tenants of the Building for after-
hours heating and air conditioning service and other special services and (to
the extent that Operating Expenses include the cost of any repair or
reconstruction work) the amount of any insurance recoveries, shall be credited
against Operating Expenses in computing the amount thereof. Operating Expenses
shall also be reduced as provided in Section 3(b).  Operating Expenses shall not
include  financing or mortgage costs; depreciation expense; advertising for
vacant space or building promotion; leasing commissions; executive salaries or
compensation to any employee of Landlord or its property management company
above the rank of the property manager assigned to the Building; more than one-
fourth (1/4) of the salary and benefits of the property manager assigned to the
Building; the cost of tenant improvements; legal fees for leasing vacant space
in the Building or enforcing Landlord's rights under leases with tenants for
space in the Building; or charges for electricity used directly by Tenant or by
other tenants of the Building.  Operating Expenses also shall not include:
costs of additional insurance premiums for the Building due to any tenant's
operations within such tenant's demised premises, which are payable by such
tenant under such tenant's lease; the cost of repairs or replacements incurred
by reason of fire or other casualty; or any other costs or

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expenses for which Landlord actually receives reimbursement from any source
(other than amounts paid by tenants of the Building with respect to Operating
Expenses), including, without limitation, insurance proceeds, condemnation
awards or warranties.

          Penthouse: The Floor immediately above the Twelfth Floor.

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

          Real Estate Taxes: All taxes, assessments, vault rentals, water and
sewer rents, if any, and other charges, if any, general, special or other wise,
including all assessments for schools, public betterments and general or local
improvements, levied or assessed upon or with respect to the ownership of and/or
all other taxable interests in the Building and the land on which it is built
imposed by any public or quasi-public authority having jurisdiction and personal
property taxes levied or assessed on Landlord's personal property used in
connection with the operation, maintenance and repair of the Building.  Real
Estate Taxes shall not include any inheritance, estate, succession, transfer,
recordation, gift, franchise, corporation, income or profit tax or capital levy.
If at any time during the Term the methods of taxation shall be altered so that
in addition to or in lieu of or as a substitute for the whole or any part of any
Real Estate Taxes levied, assessed or imposed there shall be levied, assessed or
imposed (i) a tax, license fee, excise or other charge on the rents received by
Landlord, or (ii) any other type of tax or other imposition (except those
excluded from Real Estate Taxes in the preceding sentence) in lieu of, or as a
substitute for, or in addition to, the whole or any portion of any Real Estate
Taxes, then the same shall be included as Real Estate Taxes.  A tax bill or true
copy thereof, together with any explanatory or detailed statement of the area or
property covered thereby, submitted by Landlord to Tenant shall be conclusive
evidence of the amount of taxes assessed or levied, as well as of the items
taxed.  If any real property tax or assessment levied against the land,
buildings or improvements covered thereby or the rents reserved therefrom, shall
be evidenced by improvement or other bonds, or in other form, which may be paid
in annual installments, only the amount paid or payable in any Lease Year shall
be included as Real Estate Taxes for that Lease Year.

          Taking: A taking of property or any interest therein or right
appurtenant or accruing thereto, by condemnation or eminent domain or by action,
proceedings, or agreement in lieu thereof, pursuant to governmental authority.

          Tenant: The tenant named herein and any permitted assignee under
Section 15.

          Tenant's Special Installations: As defined in Section 9(d).

          Unavoidable Delays: Delays caused by strikes, acts of God, lockouts,
labor difficulties, riots, explosions, sabotage, accidents, inability to obtain
labor or materials, governmental restrictions, enemy action, civil commotion,
fire, unavoidable casualty or similar causes beyond the reasonable control of
the Landlord or the Tenant, as the case may be.No payment of any monetary
amounts required of, or the obtaining or delivery of any required insurance
policies by, either Landlord or Tenant shall be delayed or excused by acts of
Unavoidable Delay.

          2.  Condition of Premises.

          Tenant accepts the Leased Premises in their as-is, where-is condition
as of the date of this Lease, subject to any and all deficiencies and defects
therein, and without any express or implied warranties of habitability, fitness,
fitness for a particular purpose or otherwise.

          3.  Rent and Additional Charges.

          (a) Payment of Rent and Additional Charges. Tenant shall pay the Basic
Rent for each Lease Year in equal monthly installments in advance on the first
(1st) day of each month during the Term. The Basic Rent and all Additional
Charges shall be paid promptly when due, in lawful money of the United States,
without notice or

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demand and without deduction, diminution, abatement, counterclaim or setoff of
any amount or for any reason whatsoever, except as otherwise expressly provided
in subsections (b) and (h) and Sections 13 and 14, to Landlord by wire transfer
to such bank account as Landlord may from time to time designate. If Tenant
makes any payment to Landlord by check (which, for any payment other than by
wire transfer, shall require Landlord's consent), such payment shall be by check
of Tenant and Landlord shall not be required to accept the check of any other
person, and any check received by Landlord shall be deemed received subject to
collection. If any check is mailed by Tenant, Tenant shall post such check in
sufficient time prior to the date when payment is due so that such check will be
received by Landlord on or before the date when payment is due. Tenant shall
assume the risk of lateness or failure of delivery of the mails, and no lateness
or failure of the mails will excuse Tenant from its obligation to have made the
payment in question when required under this Lease. All bank service charges
resulting from any bad checks shall be borne by Tenant. The rent reserved under
this Lease shall be the total of all Basic Rent and Additional Charges,
increased and adjusted as elsewhere herein provided, payable during the entire
Term and, accordingly, the methods of payment provided for herein, namely,
annual and monthly rental payments, are for convenience only and are made on
account of the total rent reserved hereunder.

          (b) Payment of Operating Expense Increases.  Tenant shall pay as
additional rent Operating Expense Increases for each calendar year, commencing
with the calendar year in which the Operating Expense Commencement Date occurs.
Landlord shall make a reasonable estimate of Tenant's Operating Expense
Increases for each calendar year (based on the projected Real Estate Taxes
payable for the real estate tax fiscal years included in such calendar year, the
other Operating Expenses for the preceding calendar year and known increases in
other Operating Expenses for the current calendar year), and Tenant shall pay to
Landlord 1/12th of the amount so estimated on the first day of each month in
advance, beginning on January 1, 1998 and continuing thereafter throughout the
Term.  If Landlord's estimate of Tenant's Operating Expense Increases for any
calendar year is received by Tenant after January 1 of the calendar year, Tenant
shall pay to Landlord in a lump sum, within 15 days after receipt of the
estimate, the arrearages in the monthly estimates for each month in the calendar
year before receipt of the estimate and shall pay the remaining monthly
installments on the first day of each month in advance during the balance of the
calendar year.  Within 150 days after the end of each calendar year, Landlord
shall submit to Tenant a statement prepared by an independent certified public
accountant setting forth in reasonable detail the Operating Expenses for such
calendar year and the amount of Tenant's Operating Expense Increases for such
calendar year.  If Tenant's Operating Expense Increases so stated are more than
the amount theretofore paid by Tenant for Operating Expense Increases based on
Landlord's estimate, Tenant shall pay to Landlord the deficiency within 15 days
after the submission of such statement.  If Tenant's Operating Expense Increases
so stated are less than the amount theretofore paid by Tenant for Operating
Expense Increases based on Landlord's estimate, Landlord shall refund to Tenant
the excess within 15 days after submission of such statement or Landlord, at its
option, shall credit the excess against the next monthly installment of Basic
Rent thereafter payable by Tenant under this Lease.  Tenant, at its sole cost
and expense, shall have the right, at reasonable times and upon reasonable
notice given within 90 days after receipt of a statement for Tenant's Operating
Expense Increases for any calendar year, to audit the statements furnished to
Tenant for such calendar year.  If either the Operating Expense Commencement
Date shall not coincide with the beginning of a calendar year or the last day of
the Term shall not coincide with the end of a calendar year, then the amount of
Operating Expense Increases payable for the calendar year in which the Operating
Expense Commencement Date or the last day of the Term occurs, as the case may
be, shall be pro-rated on a daily basis between Landlord and Tenant based on the
number of days in such calendar year after the Operating Expense Commencement
Date or before the last day of the Term.  Tenant's obligations under this
subsection to pay Operating Expense Increases and Landlord's obligation to
reimburse Tenant for an overpayment of Operating Expenses shall survive the
expiration of the Term.

          (c)  Gross Up of Operating Expenses.

          (1)  If, during all or any part of a calendar year, any part of the
Building Rentable Area is leased to a tenant (hereinafter referred to as a
"Special Tenant") pursuant to a Lease in which operating expenses are not
defined to include substantially the same components as the Operating Expenses
(as defined in Section 1(c), the Operating Expenses for such calendar year shall
be deemed to equal the Operating Expenses, as reasonably

                                      -7-
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estimated by Landlord, that would have been incurred by Landlord if all Special
Tenant's leases included substantially the same components as the Operating
Expenses.

          (2)  If the average occupancy level of the Building for any calendar
year is less than 95%, the Operating Expenses for such calendar year shall be
deemed to equal the amount of Operating Expenses, as reasonably estimated by
Landlord, that would have been incurred by Landlord during such calendar year if
the average occupancy level of the Building for the calendar year had been 95%.
For purposes of the preceding sentence, the "average occupancy level of the
Building" for any calendar year shall be the arithmetic average of the Building
Rentable Area occupied by tenants on the first day of each month during the
calendar year.

          (3)  If, during any calendar year, any part of the Building Rentable
Area is leased to a Special Tenant and the average occupancy level of the
Building is less than 95%, Landlord may make both the adjustments to Operating
Expenses in paragraph (1) and the adjustment to Operating Expenses in paragraph
(2).

          (d) Interest.  If Tenant fails to make any payment of Basic Rent or
Additional Charges by the earlier of (i) 5 business days after the due date
thereof or (ii) 7 days after the due date thereof, interest shall, at Landlord's
option, accrue on the unpaid portion thereof from the due date at the Default
Interest Rate, but in no event at a rate higher than the maximum rate allowed by
law, and shall be payable on demand.

          (e) Accord and Satisfaction.  No payment by Tenant or receipt by
Landlord of any lesser amount than the amount stipulated to be paid hereunder
shall be deemed other than on account of the earliest stipulated Basic Rent or
Additional Charges; nor shall any endorsement or statement on any check or
letter be deemed an accord and satisfaction, and Landlord may accept any check
or payment without prejudice to Landlord's right to recover the balance due or
to pursue any other remedy available to Landlord.

          (f) Late Payment Charge.  If Tenant fails to pay any Basic Rent or
Additional Charges by the earlier of (i) 5 business days after the due date
thereof or (ii) 7 days after the due date thereof, Tenant shall also pay to
Landlord on demand a late payment service charge (to cover Landlord's
administrative and overhead expenses of processing late payments) equal to the
greater of $100.00 or 5% of such unpaid sum for each and every calendar month or
part thereof after the due date that such sum has not been paid to Landlord.
Such payment shall be deemed liquidated damages and not a penalty, but shall not
excuse the untimely payment of rent.

          (g) Reduction of Real Estate Taxes.  Landlord shall give Tenant a copy
of any tax assessment notice with respect to the Building within 15 days after
receipt thereof.  Landlord will use reasonable efforts to obtain a reduction of
Real Estate Taxes, provided Tenant and other tenants in the Building which,
together with Tenant, occupy, collectively, at least fifty percent (50%) of the
Building Rentable Area, make a written request to Landlord so to do and, in such
request, each agrees to pay its proportionate share of the costs thereof as
hereinafter provided, and Landlord receives such request not less than 20 days
prior to the last day on which Real Estate Tax reduction proceedings for the
particular real estate tax year in question may be commenced.  The method and
manner of conducting proceedings for such reduction, including the selection of
counsel, shall be solely within the judgment and determination of Landlord, and
Landlord may cancel, discontinue or settle such proceedings if, in Landlord's
judgment, such cancellation, discontinuance or settlement is advisable.
Landlord shall keep Tenant informed of the status of any such proceeding.  If
Landlord determines to cancel or discontinue such proceeding, Tenant shall have
the right, either alone or with other tenants of the Building, to continue such
proceeding at its or their own expense.  To the extent that the reasonable costs
and expenses, including legal fees, of such proceedings instituted and conducted
by Landlord, requested by Tenant and others, exceed the amount of any tax
refund, Tenant shall pay that proportion of such excess cost and expense which
the Rentable Area of the Leased Premises bears to the total rentable area leased
to all tenants making such request at the time it is made.

          (h) Abatement of Basic Rent.  If, because of Landlord's failure to
provide any of the services referred to in Sections 5(h), all or substantially
all of the Leased Premises becomes untenantable and Tenant is unable to and does
not, in fact, use all or substantially all of the Leased Premises for the uses
permitted by Section

                                      -8-
<PAGE>

6(a) for a continuous period of 10 Business Days, then provided the cause of
such cessation of services is not the result, in whole or in principal part, of
Tenant's negligence or intentional misconduct, Tenant shall be entitled to an
abatement of Basic Rent for the period of time in which Tenant is unable to use,
and does not, in fact, use all or substantially all of the Leased Premises for
the uses permitted by Section 6(a). Any dispute between Landlord and Tenant as
to Tenant's entitlement to an abatement of Basic Rent shall be submitted to
mediation pursuant to Section 28.

          (i) Retroactive Rent Adjustment.  Subject to the availability of Net
Cash Flow, as defined in Section 2.2 of the Limited Liability Company Agreement
of Hunters Branch Partners, L.L.C., reduced only by the Retroactive Rent
Adjustments described herein and in Tenant's Lease for premises in 9300 Lee
Highway, Vienna, Virginia ("Available Cash Flow"), Tenant shall receive
Retroactive Rent Adjustments in the following amounts for the following 12-month
periods ("Adjustment Years") during the Term:

<TABLE>
<CAPTION>
          Adjustment Year      Amount of Rent Adjustment
          <S>                  <C>
          11/1/97 - 10/31/98    $134,728.00
          11/1/98 - 10/31/99     137,021.00
          11/1/99 - 10/31/00     143,517.00
          11/1/00 - 10/31/01     153,928.00
          11/1/01 - 10/31/02     159,774.00
          11/1/02 - 10/31/03     103,212.00
          11/1/03 - 10/31/04     108,026.00
          11/1/04 - 10/31/05     118,388.00
          11/1/05 - 10/31/06     120,309.00
          11/1/06 - 10/31/07      76,780.00
          11/1/07 - 10/31/08     131,366.00
          11/1/08 - 10/31/09     131,838.00
          11/1/09 - 10/31/10     149,229.00
          11/1/10 - 10/31/11     175,687.00
          11/1/11 - 10/31/12     189,519.00
</TABLE>

          Subject to Available Cash Flow, the Retroactive Rent Adjustment shall
be paid by Landlord to Tenant in equal monthly installments in arrears.  If the
monthly installment of the Retroactive Rent Adjustment for any month is not
fully paid because of the lack of Available Cash Flow, then the unpaid portion
shall be paid in a later month of the Term (if any) when there is sufficient
Available Cash Flow to pay such unpaid portion.  Landlord agrees that it will
not pay, and Tenant agrees that it will not accept, a Retroactive Rent
Adjustment for any month during any Adjustment Year unless the Annual Priority
Return (as defined in Section 2.2 of the Limited Liability Company Agreement of
Hunters Branch Partners, L.L.C.) for such month (together with accrued interest,
if any) has been paid by Hunters Branch Partners, L.L.C. to the Person entitled
to receive such payment.

          (j) Lease Restructuring Fee.  Upon execution of this Lease, Tenant has
paid Landlord a Lease Restructuring Fee in the amount of $208,257.12, receipt of
which is hereby acknowledged by Landlord.

          4.  Common Areas.

          Throughout the Term, Tenant and its agents, employees and business
invitees shall have the non-exclusive right, in common with other tenants of the
Building and the adjacent office building, to use the public lobbies, elevators,
corridors, stairways, parking garage, sky walk, patios, sidewalks, roadways and
other common areas in the Building and the Land, and the toilet rooms in public
areas of multi-tenant floors in the Building.  Landlord shall have the right to
rent parking spaces in the parking garage to persons other than tenants of the
Building and the adjacent office building with Tenant's prior written approval,
which approval shall not be unreasonably withheld, and which approval shall be
deemed given provided that (i) no third party parking contract

                                      -9-
<PAGE>

shall be for a period of more than one (1) month, (ii) access to the parking
garage shall be controlled by access or key cards, and (iii) reasonable security
shall be provided with respect to the parking garage area. Landlord shall have
the right at any time, without the Tenant's consent, to change the arrangement
or location of entrances, passageways, doors, doorways, corridors, stairs,
toilet rooms or other public portions of the Building, provided any such change
does not unreasonably obstruct Tenant's access to the Leased Premises.

          5.   Services and Utilities.

          (a)  Building Services.  Throughout the Term, Landlord agrees that the
Building will be managed and maintained in accordance with generally accepted
industry practices and in a manner befitting a modern, first class rental office
building in Fairfax County, Virginia, and that, subject to Legal Requirements,
it will furnish to Tenant the following services:

          (1)  Subject to the provisions of subsection (b), normal and usual
electricity for lighting purposes and the operation of ordinary office
equipment;

          (2)  Adequate supplies for toilet rooms located in public areas of the
Building;

          (3)  Normal and usual cleaning and janitorial services after business
hours on Business Days in accordance with the standards set forth in Exhibit D
attached hereto and made a part hereof, provided, however, that Landlord shall
not provide cleaning and janitorial services to the double-secured areas of the
Leased Premises;

          (4)  Hot and cold running water in the toilet rooms located in public
areas of the Building and at valved outlets at the locations in the Leased
Premises shown on Tenant's Space Layout;

          (5)  Subject to the provisions of subsections (c) and (e), heating and
air-conditioning to the Leased Premises when required for the comfortable
occupancy of the Leased Premises, at reasonable temperatures, pressures and
degrees of humidity, and in reasonable volumes and velocities, between the hours
of 8:00 A.M.  and 7:00 P.M.  on Business Days and between the hours of 9:00 A.M.
and 1:00 P.M.  on Saturdays unless Saturday is a legal holiday;

          (6)  Automatically operated elevator facilities 24 hours a day, seven
days a week throughout the Term;

          (7)  All electric bulbs and fluorescent tubes in permanently installed
light fixtures in the Leased Premises and in the public areas of the Building;

          (8)  Five (5) keys for the suite entry door to each portion of the
Leased Premises located on a separate Floor at no cost to Tenant, but all
additional keys, including replacements for lost keys, shall be issued only upon
the payment of a reasonable cost for each additional key;

          (9)  An electronic card security access system for the public areas of
the Building and the garage and a reasonable number of access cards for use by
Tenant's employees; and

          (10) A fully-operational structured parking facility for use by
tenants of the Building with access limited to Persons authorized by Tenant or
Landlord.

          (b)  Electricity.  Landlord shall not be liable in any way to Tenant
for any failure or defect in the supply or character of electrical energy
furnished to the Leased Premises by reason of any requirement, act or omission
of the public utility serving the Building with electricity.  Tenant's use of
electrical energy in the Leased Premises shall not at any time exceed the
capacity of any of the electrical conductors and equipment in or otherwise
serving the Leased Premises as shown on Landlord's Building Plans.  Tenant shall
not install or operate in the

                                      -10-
<PAGE>

Leased Premises any electrically operated equipment which uses electric current
in excess of the capacity of the feeders and panel boards serving the Leased
Premises as shown on Landlord's Building Plans without Landlord's written
consent, which consent may be conditioned upon Tenant's agreement to pay the
cost of any additional wiring which may be required for the operation of such
equipment. In order to insure that such capacity is not exceeded and to avert a
possible adverse effect upon the Building electrical service Tenant shall give
notice to Landlord whenever Tenant shall connect to the Building electrical
distribution system any electrically operated equipment other than lamps,
typewriters and similar small office machines. Any feeders or risers to supply
Tenant's electrical requirements in addition to those originally installed, 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 sole cost
and expense of Tenant, provided that, in Landlord's reasonable judgment, such
additional feeders or risers are permissible under applicable laws and insurance
regulations and the installation of such feeders or risers will not cause
permanent damage or injury to the Building or cause or create a dangerous
condition or unreasonably interfere with other tenants of the Building. All
Floors occupied entirely by Tenant shall be separately metered or sub-metered
for electricity and all other parts of the Leased Premises, may, at Landlord's
option, be separately metered or sub-metered for electricity. Tenant shall pay
(or reimburse Landlord for) the cost of purchasing and installing separate
electric meters or sub-meters for each whole Floor and each part of a Floor
included in the Leased Premises, and for any other part of the Leased Premises
which Landlord elects to have metered or sub-metered. Tenant shall pay directly
to the public utility company all charges for electricity used by Tenant in all
parts of the Leased Premises which are separately metered, or Tenant shall
reimburse Landlord directly for its electrical usage in all parts of the Leased
Premises which are sub-metered. Landlord shall have the right from time to time
to have a survey made by an independent electrical engineer or electrical
consulting firm to be selected and paid for by Landlord to determine the amount
of electricity consumed by Tenant in the parts of the Leased Premises which do
not consist of an entire Floor. Tenant shall pay to Landlord, at monthly
intervals upon receipt of an invoice therefor, the cost of electricity it
consumes in the parts of the Leased Premises which do not consist of an entire
Floor as determined by such electrical engineer or consulting firm.

          (c) Heating and Air-Conditioning.  Landlord shall provide heat and
air-conditioning at times in addition to those specified in paragraph (5) of
subsection (a) at Tenant's expense, provided Tenant gives Landlord notice prior
to 3:00 P.M.  ( in the case of after-hours service on weekdays) and prior to
3:00 P.M. on Fridays or the day preceding a holiday (in the case of after-hours
service on Saturdays, Sundays or holidays).  In no event will the rate per hour
charged to Tenant for after-hours service be more than an amount per hour which
represents Landlord's reasonable estimate of its actual cost of providing such
after-hours heating and air-conditioning service, including labor and wear and
tear on equipment, but excluding the cost of electricity.  Payment for such
charges shall be due and payable to Landlord within 15 days after Tenant's
receipt of an invoice therefor.

          (d) Maintenance of Pipes, Conduits, etc.  Landlord reserves the right
to erect, use, maintain and repair pipes, conduits, cables, plumbing, vents and
wires in, to and through the Leased Premises as and to the extent that Landlord
may now or hereafter deem to be necessary or appropriate for the proper
operation and maintenance of the Building, or other tenants' installations in
the Building, and the right at all times to transmit water, heat, air-
conditioning and electric current through such pipes, conduits, cables,
plumbing, vents and wires, provided that Landlord, in the exercise of such
rights, shall not unreasonably inconvenience Tenant or unreasonably interfere
with Tenant's use of the Leased Premises.

          (e) HVAC Specifications.  Landlord agrees that the air-conditioning
system in the portion of the Leased Premises consisting of Office Space will be
capable of providing, and (unless otherwise ordered by federal, state or local
governmental authorities) the system shall provide, temperatures of not more
than 77 degrees F dry bulb and a relative humidity not in excess of 50% with
outside conditions of 95 degrees F dry bulb and 78 degrees F wet bulb, except as
otherwise provided in this subsection. Landlord agrees that the heating system
in the portion of the Leased Premises consisting of Office Space will be capable
of providing, and (unless otherwise ordered by federal, state or local
governmental authorities) the system shall provide, temperatures of not less
than 70 degrees F whenever the outdoor dry bulb temperature is lower than 65
degrees F but no lower than 0 degrees F, with indoor relative humidity at such
level as not to permit the formation of condensation on the windows. Landlord
shall not be responsible if the normal

                                      -11-
<PAGE>

operation of the Building air-conditioning system shall fail to provide
conditioned air at reasonable temperatures, pressures or degrees of humidity or
in reasonable volumes or velocities in any portions of the Leased Premises
consisting of Office Space which (i) shall have a connected electrical load in
excess of three watts per square foot of Rentable Area of the Leased Premises
for all purposes (including lighting and power) or which shall have a human
occupancy factor in excess of one person for each 100 square feet of Rentable
Area of the portion of the Leased Premises consisting of Office Space (the
average electrical load and human occupancy factors for which the Building air-
conditioning system is designed), or (ii) because of rearrangement of
partitioning or other Alterations made by or on behalf of Tenant or any Person
claiming through or under Tenant (excepting work performed by Landlord for
Tenant prior to Tenant's initial occupancy of the Leased Premises).

          (f) Access to HVAC Facilities.  Landlord shall have unrestricted
access to any and all air-conditioning facilities in the Leased Premises for the
purposes of repairs, maintenance, alterations and improvements, but in
exercising its rights under this subsection Landlord shall use its best efforts
to minimize interference with Tenant's business in the Leased Premises.
Notwithstanding anything to the contrary herein or in Section 5(d), except in
the event of an emergency, Landlord may obtain access to the double-secured
areas of the Leased Premises only with the permission and assistance of Tenant's
Director of Facilities or his designee.  Tenant shall provide Landlord with keys
to the double-secured areas of the Leased Premises.  Tenant's Director of
Facilities, or his designee, shall be available to provide access to the double-
secured areas of the Leased Premises on a non-emergency basis promptly after
Landlord's request for permission to enter the same, and in any event no later
than 24 hours after such request.

          (g) Reduction of Air-Conditioning Use.  Tenant agrees to use
reasonable efforts to keep or cause to be kept closed all window draperies or
venetian blinds in the Leased Premises as and when necessary because of the
sun's position whenever the air-conditioning system is in operation, and Tenant
agrees at all times to cooperate fully with Landlord and to abide by all the
reasonable regulations and requirements which Landlord may prescribe for the
proper functioning and protection of the Building air-conditioning system.

          (h) Cessation of HVAC and Mechanical Services.  Landlord reserves the
right to stop the service of heating, air-conditioning, ventilating, elevator,
plumbing, electricity or other mechanical systems or facilities in the Building,
if necessary by reason of accident or emergency, or for repairs, alterations,
replacements, additions or improvements which, in the reasonable judgment of
Landlord, are desirable or necessary, until said repairs, alterations,
replacements, additions or improvements shall have been completed.  The exercise
of such right by Landlord shall not constitute an actual or constructive
eviction, in whole or in part, or relieve Tenant from any of its obligations
under this Lease, or impose any liability upon Landlord or its agents by reason
of inconvenience or annoyance to Tenant, or injury to, or interruption of,
Tenant's business, or otherwise, or entitle Tenant to any abatement or
diminution of rent except as provided in Section 3(h).  Except in cases of
emergency repairs, Landlord will give Tenant reasonable advance notice of any
contemplated stoppage of any such systems or facilities pursuant to the
foregoing.  In all cases, Landlord will use due diligence to complete any such
repairs, alterations, replacements, additions or improvements promptly.
Landlord shall also perform any such work in a manner designed to minimize
interference with Tenant's normal business operations.

          6.  Use of Leased Premises.

          (a) Permitted Uses.  Tenant shall use and occupy the portion of the
Leased Premises consisting of Office Space solely for general office purposes,
and shall use and occupy the portion of the Leased Premises consisting of
Storage Space solely for storage, all in accordance with the applicable zoning
regulations and consistent with the character and dignity of the Building, and
shall not use, permit or suffer the use of the Leased Premises for any other
purpose whatsoever without the prior written consent of the Landlord.  Tenant
shall not use, or permit the Leased Premises to be used, for the sale of food,
beverages or tobacco products, except that Tenant may operate on the Leased
Premises vending machines for the sale of food, beverages and tobacco products
to its employees.  Tenant shall not permit or suffer the Leased Premises to be
occupied by anyone other than Tenant except as provided by Section 15.  Tenant
shall at all times have access to the Leased Premises 24 hours a day,

                                      -12-
<PAGE>

seven days a week, subject, however, in all respects to all the terms, covenants
and conditions contained in this Lease. However, Landlord may regulate and
restrict access to the Building at times other than normal business hours on
Business Days for security purposes so long as Tenant ' s employees and agents
have reasonable access to the Leased Premises without unreasonable
inconvenience.

          (b) Restrictions on Use.  Throughout the Term, Tenant covenants and
agrees: (i) to pay 10 days before delinquency any and all taxes, assessments and
public charges levied, assessed or imposed upon Tenant's business conducted in
the Leased Premises, upon the leasehold estate created by this Lease or upon
Tenant's fixtures, furnishings or equipment in the Leased Premises; (ii) not to
use or permit or suffer the use of any portion of the Leased Premises for any
unlawful purpose; (iii) not to use the plumbing facilities for any purpose other
than that for which they were constructed, or dispose of any foreign substances
therein; (iv) not to place a load on any floor exceeding the floor load per
square foot which such floor was designed to carry in accordance with Landlord's
Building Plans, and not to install, operate or maintain in the Leased Premises
any heavy item of equipment except in such manner as to achieve a proper
distribution of weight; (v) not to strip, overload, damage or deface the Leased
Premises, or the hallways, stairways, elevators, parking facilities or other
public areas of the Building, or the fixtures therein or used therewith; (vi)
not to move any furniture or equipment into or out of the Leased Premises except
at such times as Landlord may from time to time reasonably designate; (vii) not
to use any floor adhesive in the installation of any carpeting; (viii) not to
install any other equipment of any kind or nature which will or may necessitate
any changes, replacements or additions to, or in the use of, the water system,
heating system, plumbing system, air-conditioning system or electrical system of
the Leased Premises or the Building, without first obtaining the written consent
of Landlord; and (ix) at all times to comply with all Legal Requirements.

          (c) Compliance with Legal Requirements.  Tenant will not use or occupy
     the Leased Premises in violation of any Legal Requirements.  If any
     governmental authority, after the commencement of the Term, shall contend
     or declare that the Leased Premises are being used for a purpose which is
     in violation of any Legal Requirements, then Tenant shall, upon five days'
     notice from Landlord, immediately discontinue such use of the Leased
     Premises.  If thereafter the governmental authority asserting such
     violation threatens, commences or continues criminal or civil proceedings
     against Landlord for Tenant's failure to discontinue such use, in addition
     to any and all rights, privileges and remedies given to Landlord under this
     Lease for default therein, Landlord shall have the right to terminate this
     Lease forthwith.  Tenant shall indemnify and hold Landlord harmless from
     and against any and all liability for any such violation or violations.

          (d) Compliance with Insurance Requirements.  Tenant shall not do,
permit or suffer to be done any act, matter, thing or failure to act in respect
of the Leased Premises and/or the Building that will invalidate or be in
conflict with fire insurance policies covering the Building or any part thereof,
and shall not do, or permit anything to be done, in or upon the Leased Premises
and/or the Building, or bring or keep anything therein, which shall increase the
rate of fire insurance on the Building or on any property located therein.  If,
by reason of the failure of Tenant to comply with the provisions of this
subsection, the fire insurance rate shall at any time be higher than it
otherwise would be, then Tenant shall reimburse Landlord and any other tenant of
the Building, on demand, for that part of all premiums for any insurance
coverage that shall have been charged because of such violation by Tenant and
which Landlord or such other tenant, or both, shall have paid on account of an
increase in the rate or rates in its own policies of insurance.  Tenant shall
not be responsible for any increase in fire insurance rates generally applicable
to office space in Fairfax County, Virginia, and not resulting from the
particular manner in which Tenant uses the Leased Premises.

          (e) No Flammable Substances.  Tenant shall not bring or permit to be
brought or kept in or on the Leased Premises any flammable, combustible or
explosive fluid, material, chemical or substance except standard cleaning fluid,
standard equipment and materials (including magnetic tape) customarily used in
conjunction with business machines and equipment of the type used from time to
time by Tenant in reasonable quantities.

                                      -13-
<PAGE>

          7.  Care of Leased Premises.

          (a) By Tenant. Tenant shall act with care in its use and occupancy of
the Leased Premises and the fixtures therein and, at Tenant's sole cost and
expense, shall make all repairs and replacements to the Leased Premises,
structural or otherwise, necessitated or caused by the acts, omissions or
negligence of Tenant or any Person claiming through or under Tenant or by the
use or occupancy or manner of use or occupancy of the Leased Premises by Tenant
or any such Person; however the foregoing provisions of this subsection shall be
subject to the provisions of Section 13.  Without affecting Tenant's obligations
set forth in the preceding sentence, Tenant, at Tenant's sole cost and expense,
shall also (i) make all repairs and replacements, as and when necessary, to
Tenant's Special Installations and to any Alterations made or performed by or on
behalf of Tenant or any Person claiming through or under Tenant, (ii) perform
all maintenance and make all repairs and replacements, as and when necessary, to
any air-conditioning equipment, private elevators, escalators, conveyors or
mechanical systems (other than the standard equipment and systems serving the
Building) which may be installed in the Leased Premises, or elsewhere in the
Building and serving the Leased Premises, by Landlord, Tenant or others, (iii)
perform all maintenance and make all repairs and replacements, as and when
necessary, to the antennas and satellite dishes installed by Tenant on the roof
of the Building and make all repairs to the roof caused by such installation,
and (iv) perform regular cleaning and janitorial services in the double-secured
areas of the Leased Premises.  However, except as otherwise provided in this
Lease, Tenant shall not have any right to install air-conditioning equipment,
elevators, escalators, conveyors or mechanical systems.  In addition to the
foregoing, all damage or injury to the Leased Premises and to its fixtures,
appurtenances and equipment or to the Building or to its fixtures, appurtenances
and equipment caused by Tenant moving property in or out of the Building or by
installation or removal of furniture, fixtures or other property by Tenant shall
be repaired, restored or replaced promptly by Tenant, at its sole cost and
expense, to the reasonable satisfaction of Landlord.  All such aforesaid
repairs, restoration and replacements shall be in quality and class equal to the
original work or installation but in no event need exceed Building standards.

          (b) By Landlord. Except as otherwise provided in subsection (a),
Landlord shall perform the following maintenance and repairs as and when
necessary (the costs of which shall be Operating Expenses hereunder, to the
extent included in the definition of Operating Expenses in Section 1(c)): (i)
structural repairs to the Leased Premises and Building; (ii) maintenance and
repairs required in order to provide the elevator, plumbing, electrical, heating
and air-conditioning services to be furnished by Landlord pursuant to this
Lease; (iii) maintenance of and repairs to exterior portions of the Building,
including the windows, balconies and roof thereof; (iv) maintenance of and
repairs to the toilet rooms in the Building, and to the public lobbies,
elevators, corridors, stairways, parking garage, sky walk, patios, sidewalks,
roadways and other common areas in the Building and the Land;  and (v) other
repairs to the Leased Premises and the Building necessary for Tenant's use and
enjoyment of the Leased Premises.  Landlord's obligations to make repairs to the
Leased Premises (but not the Building) under the preceding sentence shall not
accrue until after notice to Landlord of the necessity for any specific repair.

          8.  Rules and Regulations.

          Tenant and its agents and employees shall comply with and observe all
reasonable rules and regulations concerning the use, management, operation,
safety and good order of the Leased Premises and the Building which may from
time to time be promulgated by Landlord, provided that such rules and
regulations are not inconsistent with the provisions of this Lease and do not
materially interfere with Tenant's use of the Leased Premises.  Initial rules
and regulations, which shall be effective until amended by Landlord, are
attached to this Lease as Exhibit E hereto and made a part hereof.  Tenant shall
be deemed to have received notice of any amendment to the rules and regulations
when a copy of such amendment has been delivered to Tenant at the Leased
Premises or has been mailed to Tenant in the manner prescribed for the giving of
notices.  If Tenant disputes the reasonableness of any additional rule or
regulation hereafter made or adopted by Landlord, the parties agree to submit
the question of the reasonableness of such rule or regulation for decision to
the governing board for the time being of the Building Owners and Managers
Association of Washington, D.C., or to such impartial person or persons as it or
the parties hereto may designate, whose determination shall be final and
conclusive upon the parties

                                      -14-
<PAGE>

hereto. Tenant may not dispute the reasonableness of any additional rule or
regulation unless Tenant 's intention to do so shall be asserted by notice given
to Landlord within 15 days after notice is given to Tenant of the adoption of
any such additional rule or regulation. Landlord shall not be responsible to
Tenant for any violation of the rules and regulations, or the covenants or
agreements contained in any other lease, by any other tenant of the Building, or
such tenant's agents or employees, and Landlord may waive in writing, or
otherwise, any or all of the rules or regulations in respect of any one or more
tenants.

          9.  Tenant's Alterations and Installments.

          (a) Restrictions on Alterations. Tenant shall not make or perform, or
permit the making or performance of, any alterations, installations,
improvements, additions or other physical changes in or about the Leased
Premises (referred to collectively as "Alterations") without Landlord's prior
consent.  Landlord agrees not unreasonably to withhold or delay its consent to
any nonstructural Alterations proposed to be made by Tenant to adapt the Leased
Premises for Tenant's business purposes or the business purposes of any other
permitted occupant of the Leased Premises, except that Landlord shall have no
obligation to consent to any Alteration which will reduce the value or utility
of the Building or affect the outside appearance of the Building or the color or
style of any venetian blinds supplied by Landlord (except that Tenant may remove
any such venetian blinds provided Tenant promptly replaces such venetian blinds
with venetian blinds of a similar type and color).  Notwithstanding the
foregoing provisions of this subsection or Landlord's consent to any
Alterations, all Alterations, whether made prior to or during the Term, shall be
made and performed in conformity with and subject to the following provisions:
(i) all Alterations shall be made and performed at Tenant's sole cost and
expense and at such time and in such manner as Landlord may reasonably from time
to time designate; (ii) Alterations shall be made only by contractors or
mechanics approved by Landlord, such approval not to be unreasonably withheld or
delayed; (iii) no Alteration shall materially affect any part of the Building
other than the Leased Premises or adversely affect any service required to be
furnished by Landlord to Tenant or to any other tenant or occupant of the
Building; (iv) all business machines and mechanical equipment shall be placed
and maintained by Tenant in settings sufficient in Landlord's reasonable
judgment to absorb and prevent vibration, noise and annoyance to other tenants
or occupants of the Building; (v) Tenant shall submit to Landlord reasonably
detailed plans and specifications for each proposed alteration and shall not
commence any such Alteration without first obtaining Landlord's approval of such
plans and specifications, which approval will not be unreasonably withheld or
delayed; (vi) all Alterations in or to the electrical facilities in or serving
the Leased Premises shall be subject to the provisions of Section 5 relating to
exceeding electrical capacity; (vii) notwithstanding Landlord's approval of
plans and specifications for any Alteration, all Alterations shall be made and
performed in full compliance with all Legal Requirements and in accordance with
the Rules and Regulations; (viii) all materials and equipment to be incorporated
in the Leased Premises as a result of all Alterations shall be of good quality;
and (ix) Tenant shall require any contractor performing Alterations to carry and
maintain at all times during the performance of the work, at no expense to
Landlord, (i) a policy of comprehensive public liability insurance, including
contractor's liability coverage, contractual liability coverage, completed
operations coverage, contractor's protective liability coverage and a broad form
property damage endorsement, naming Landlord and (at Landlord's request) any
Mortgagee of the Building and any management agent as additional named
insureds), with such policy to afford protection to the limit of not less than
$2,000,000 with respect to bodily injury or death to any number of persons in
any one accident and to the limit of not less than $1,000,000 to damage to the
property of any one owner from one occurrence, and (ii) workers' compensation or
similar insurance in the form and amounts required by the laws of the State of
Virginia.  In the event the estimated cost of an Alteration (which shall include
the aggregate cost of a series of Alterations which are reasonably aggregated
into a single project) is in excess of $100,000.00, or in the event of an
Alteration to a structural member of, or mechanical system in, the Leased
Premises, Landlord shall have the right to place other and further restrictions
and conditions thereon prior to Tenant being authorized to commence such
Alteration.  Such additional conditions may include, by way of illustration and
not of limitation, the requirement that the contractor be bonded or bondable.
In the event of any dispute between the parties as to whether or not Landlord
has acted reasonably in any case with respect to which Landlord is required,
pursuant to the provisions of this subsection (a), to do so, Tenant's sole
remedy shall be to submit such dispute to mediation pursuant to Section 28.  If
the determination in any such mediation shall be adverse to Landlord, Landlord
nevertheless shall not be liable to

                                      -15-
<PAGE>

Tenant for breach of Landlord's covenant to act reasonably, and Tenant's sole
remedy in such event shall be to proceed with the proposed Alterations. However,
if the parties are unable to settle such matter by mediation, and such matter is
submitted to litigation, Landlord's liability and Tenant's remedies shall not be
so limited.

          (b) Tenant's Right to Cure.  If Tenant shall be in default under this
Section by reason of the making of any Alteration not hereby authorized or by
reason of failure to give any notice or to obtain any approval required herein,
Tenant may cure such default within the applicable grace period provided in this
Lease for curing such default by removing such Alteration and restoring the
Leased Premises to their former condition, as provided in Section 7.

          (c) Fixtures Become Landlord's Property.  Except to the extent
specifically provided in subsection (e), all appurtenances, fixtures,
improvements, additions and other property attached to or installed in the
Leased Premises, whether by Landlord or Tenant or others, and whether at
Landlord's expense, or Tenant's expense, or the joint expense of Landlord and
Tenant, which are of a permanent nature or which cannot be removed without
structural damage to the Building, shall be and remain the property of Landlord.
Any replacements of any property of Landlord, whether made at Tenant's expense
or otherwise, shall be and remain the property of Landlord.

          (d) Tenant's Special Installations.  All furniture, furnishings and
trade fixtures, excepting lighting fixtures and equipment, but including,
without limitation, murals, carpets, rugs, business machines and equipment,
vaults, vault doors and door frames, and vault equipment, if any, safe deposit
equipment, counterscreens, grillwork, cages, partitions which are moveable,
railings, raised floors, escalators, conveyors, stairs, elevators, paneling,
equipment relating to food preparation, food storage and serving, dishwashing
and cleaning devices and air-conditioning equipment, and any other moveable
property installed by, or at the expense of Tenant, including any such property
paid for with any allowance provided by Landlord to Tenant, shall remain the
property of Tenant and are referred to herein as "Tenant's Special
Installations".  Tenant may at its expense remove any part of said property at
any time during the Term, and shall at its expense remove all of said property
at the expiration or other termination of the Term unless Landlord shall
otherwise consent in writing.  Upon removal of any or all of said property
Tenant shall then repair all damage caused by such removal.  Any of Tenant's
Special Installations which are not removed from the Leased Premises at the
expiration of the Term shall be deemed to have been abandoned by Tenant and may
be disposed of by Landlord without liability to Tenant.

          (e) Mechanics' Liens.  Notice is hereby given that Landlord shall not
be liable for any labor or materials furnished or to be furnished to Tenant upon
credit, and that no mechanic's, materialman's or other lien for any such labor
or materials shall attach to or affect the reversion or other estate or interest
of Landlord in and to the Leased Premises or the Building.  Whenever and as
often as any mechanic's lien or materialman's lien shall have been filed against
the Leased Premises or the Building based upon any act or interest of Tenant or
of anyone claiming through Tenant, or if any lien or security interest with
respect thereto shall have been filed affecting any materials, machinery or
fixtures used in the construction, repair or operation thereof or annexed
thereto by Tenant or its successors in interest, Tenant shall forthwith take
such action by bonding, deposit or payment as will remove or satisfy the lien or
other security interest and in default thereof after the expiration of 20 days
after notice to Tenant, Landlord, in addition to any other remedy under this
Lease, may pay the amount secured by such lien or security interest or discharge
the same by deposit and the amount so paid or deposited shall be collectible as
additional rent.  The provisions of this subsection shall not be applicable to
liens filed with respect to work done for Tenant's account by Landlord.

          10. Name of Building; Tenant's Signs.

          (a) Name.  Landlord agrees that, throughout the Term, it will not use
any name for the Building other than its street address without first obtaining
the Tenant's written consent, which Tenant agrees not unreasonably to withhold
or delay.  Landlord expressly reserves the right to have the Building designated
by a street number or numbers and to affix to the Building, at locations
designated by Landlord, signs indicating any such number or numbers and the name
of the Building (if any) as selected from time to time by Landlord in accordance

                                      -16-
<PAGE>

with the provisions of this subsection.  Landlord agrees that it will not
install signs on the exterior of the Building, except for (i) signs for retail
tenants, and (ii) Tenant's signs permitted by subsection (d).

          (b)    Restrictions on Exterior Signs. Except as otherwise provided in
subsection (d), Landlord has not granted to Tenant any rights in or to the roof
or the outer side of the outside walls of the Building, control of which is
hereby reserved by Landlord. Tenant shall not display or erect any lettering,
signs, advertisements, awnings or other projections on the exterior of the
Leased Premises or in the interior of the Leased Premises if visible from a
public way, except for customary hallway door lettering.

          (c)    Directory Tablets. Landlord, at its expense, shall maintain the
existing directory tablets (i) in the main lobby of the Building, (ii) in the
skywalk between the Building and the other building in the Office Park, and
(iii) on the walkway between the Building and the other building in the Office
Park, upon each of which Landlord, at Tenant's expense, will affix Tenant's name
and a reasonable number of names of its officers, partners or employees. The
size, color and style of such directories and names affixed thereto shall be
selected by Landlord.

          (d)    Tenant's Permitted Signs. Landlord shall permit Tenant
throughout the Term to install and maintain, subject to Legal Requirements, two
suitable signs on the exterior of the Building. The location, size, color and
style of Tenant's exterior signs shall be subject to Landlord's approval, such
approval not to be unreasonably withheld or delayed. Landlord hereby approves
Tenant's signs which are currently on the Building, and agrees that, if Tenant's
name is changed, Tenant, at its expense, may replace such signs with similar
signs displaying the new name.

          (e)    Access to Roof. Throughout the Term, Landlord shall permit
Tenant to install and maintain, subject to Legal Requirements and the provisions
of this Section 10(e), not more than one (1) satellite or antenna dish on the
roof of the Building ("Tenant's Roof Use").

          (i)    Landlord shall make available to Tenant access to and a
location mutually acceptable to Landlord and Tenant on the roof for the
construction, installation, maintenance, repair, operation and use of such
satellite or antenna dishes. Tenant shall screen such installations in a manner
mutually acceptable to Landlord and Tenant. Tenant shall have the right to
remove such satellite or antenna dishes and any related equipment from the
Building at the expiration or other termination of the Term of this Lease,
provided that Tenant repairs any damage occasioned by such removal. Tenant shall
pay all costs associated with the installation, maintenance, repair, use,
insurance and removal of such satellite or antenna dishes and any related
equipment.

          (ii)   Tenant shall give Landlord's Building manager reasonable
telephonic notice before any entry onto the roof of the Building by Tenant's
agents, employees or contractors, and shall permit Landlord's Building manager
to accompany Tenant's agents, employees or contractors on any such entry onto
the roof.  Except as otherwise hereinafter set forth in this Section 10(e),
Landlord shall not be liable for any claims, losses, actions, damages,
liabilities or expenses arising from any satellite or antenna dish or related
equipment installed by Tenant on the roof of the Building, or the installation,
maintenance, repair, use or removal of such dish and related equipment, unless
caused by the negligence or willful misconduct of Landlord, its agents,
employees or contractors.

          (iii)  Tenant's Roof Use shall be undertaken so as to not interfere
with the operation of other equipment on the roof of the Building or the roof of
the other building in the Office Park.  If Tenant's equipment on the roof of the
Building interferes with the operation of any such other equipment, then Tenant,
at its expense, shall take whatever measures may be necessary to eliminate such
interference.

          (iv)   If the rate of any insurance carried by Landlord is increased
as a result of Tenant's Roof Use, then Tenant will pay to Landlord within ten
(10) days before the date Landlord is obligated to pay a premium on the
insurance (or within ten (10) days after Landlord delivers to Tenant a certified
statement from Landlord's insurance carrier stating that the rate increase was
caused by Tenant's Roof Use, whichever date is later), a sum equal to the
difference between the original premium and the increased premium resulting from
Tenant's Roof Use.

                                      -17-
<PAGE>

          (v)   Landlord has not made any representations or promises pertaining
to the suitability of the Building's roof for Tenant's Roof Use.  Tenant, solely
for the purpose of this Section 10(e) and its right to rooftop access hereunder,
accepts the rooftop in its "as is" condition.

          (vi)  Tenant will obtain prior to installation, any and all
governmental licenses, approvals necessary for the installation, maintenance and
use of any equipment installed pursuant to this Section 10(e).  Tenant's Roof
Use shall not in any way conflict with any applicable Legal Requirements.
Tenant shall indemnify and hold Landlord harmless from and against any and all
loss, cost (including reasonable attorney's fees incurred in defending
Landlord), damage or liability arising out of any violation by Tenant's Roof Use
of any applicable Legal Requirements.

          (vii) Tenant's Roof Use shall be exercised: (1) in such manner as
will not create any hazardous condition or interfere with or impair the
operation of the heating, ventilation, air conditioning, plumbing, electrical,
fire protection, life, safety, public utilities or other systems or facilities
in the Building; (2) in compliance with all applicable Legal Requirements; (3)
in such a manner as will not unreasonably interfere with Landlord's operation or
maintenance of the Building; (4) at Tenant's cost, including the cost of
repairing any damage to the Building and any personal injury and/or property
damage caused by the installation, inspection, adjustment, maintenance, removal
or replacement of any of Tenant's equipment on the roof; and (5) in a manner
which will not void or invalidate any roof warranty then in effect with respect
to the roof of the Building.  Tenant's Roof Use shall be used solely in the
ordinary course of Tenant's business operations (and not for resale by Tenant),
and any use of the roof outside of the ordinary course of Tenant's business
operations (such as, but not limited to, subleasing portions of the roof for
profit to third parties, in order for such third parties to establish
communications transmission facilities) shall be subject to Landlord's consent,
which consent shall not be unreasonably withheld, but may be conditioned, inter
alia, upon the payment by Tenant to Landlord of any net revenues paid to Tenant
in respect thereof.

          11.   Liability Insurance.

          (a)   Required Coverage.  Tenant, at Tenant's sole cost and expense,
shall obtain and maintain in effect at all times during the Term, a policy of
comprehensive general public liability insurance with broad form property damage
endorsement, naming Landlord and (at Landlord's request) any Mortgagee of the
Building and any management agent as additional insured(s), protecting Landlord,
Tenant and any such Mortgagee and management agent against any liability for
bodily injury, death or property damage occurring upon, in or about any part of
the Building, including the roof, or the Land, the Leased Premises or any
appurtenances thereto, with such policies to afford protection to the limit of
$5,000,000 with respect to bodily injury or death to any one person, to the
limit of $5,000,000 with respect to bodily injury or death to any number of
persons in any one accident, and to the limit of $5,000,000 with respect to
damage to the property of any one owner from one occurrence.  Such comprehensive
liability insurance may be effected by a policy or policies of blanket insurance
which cover other property in addition to the Leased Premises, provided that the
protection afforded thereunder shall be no less than that which would have been
afforded under a separate policy or policies relating only to the Leased
Premises and provided further that in all other respects any such policy shall
comply with the other provisions of this Section.

          (b)   Policy Requirements.  The insurance policy required to be
obtained by Tenant under this Section: (i) shall be issued by insurance
companies rated A- or better in the most current issue of Best's Insurance
Reports, licensed to do business in the state in which the Building is located
and domiciled in the United States; and (ii) shall be written as primary policy
coverage and not contributing with or in excess of any coverage which Landlord
may carry. Neither the issuance of any insurance policy required under this
Lease, nor the minimum limits specified herein with respect to Tenant's
insurance coverage, shall be deemed to limit or restrict in any way Tenant's
liability arising under or out of this Lease. With respect to each insurance
policy required to be obtained by Tenant under this Section, on or before the
Lease Commencement Date, and at least 30 days before the expiration of the
expiring policy or certificate previously furnished, Tenant shall deliver to
Landlord a certificate of insurance therefor, together with evidence of payment
of all applicable premiums. Each insurance policy required

                                      -18-
<PAGE>

to be carried hereunder by or on behalf of Tenant shall provide (and any
certificate evidencing the existence of each such insurance policy shall
certify) that such insurance policy shall not be canceled unless Landlord shall
have received 20 days' prior written notice of cancellation.

          (c)  Indemnification of Landlord.  Except for the willful or negligent
acts or omissions of Landlord or its agents or employees, Tenant hereby agrees
to indemnify and hold harmless Landlord from and against any and all claims,
losses, actions, damages, liabilities and expenses (including attorneys' fees)
that (i) arise from or are in connection with Tenant's possession, use,
occupancy, management, repair, maintenance or control of the Leased Premises, or
any portion thereof, or (ii) arise from or are in connection with any willful or
negligent act or omission of Tenant or Tenant's agents, employees or subtenants,
or (iii) result from any default, breach, violation or nonperformance of this
Lease or any provision therein by Tenant, or (iv) arise from injury or death to
persons or damage to property sustained on or about the Leased Premises, or (v)
arise from Tenant's installation, maintenance, repair, use or removal of any
rooftop satellite or antenna dishes or related equipment.  Tenant shall, at its
own cost and expense, defend any and all actions, suits and proceedings which
may be brought against Landlord with respect to the foregoing or in which
Landlord may be impleaded.  Tenant shall pay, satisfy and discharge any and all
money judgments which may be recovered against Landlord in connection with the
foregoing.

          (d)  Indemnification of Tenant.  Except for the willful or negligent
acts or omissions of Tenant or its agents or employees, Landlord hereby agrees
to indemnify and hold harmless Tenant from and against any and all claims,
losses, actions, damages, liabilities and expenses (including attorneys' fees)
that (i) arise from or are in connection with Landlord's possession, use,
occupancy, management, repair, maintenance or control of the common areas of the
Building located on any Floor not wholly occupied by Tenant, or (ii) arise from
or are in connection with any willful or negligent act or omission of Landlord
or Landlord's agents or employees, or (iii) result from any default, breach,
violation or nonperformance of this Lease or any provision therein by Landlord,
or (iv) arise from injury or death to persons or damage to property sustained on
or about the common areas of the Building located on any Floor not wholly
occupied by Tenant.  Landlord shall, at its own cost and expense, defend any and
all actions, suits and proceedings which may be brought against Tenant with
respect to the foregoing or in which Tenant may be impleaded.  Landlord shall
pay, satisfy and discharge any and all money judgments which may be recovered
against Tenant in connection with the foregoing.

          12.  Fire Insurance.

          (a)  Required Coverage.  Landlord shall, throughout the Term, at its
expense, keep the Building, but not Tenant's Special Installations, Alterations
or Tenant's furniture, furnishings, trade fixtures or property removable by
Tenant under the provisions of this Lease (including any rooftop satellite or
antenna dishes and related equipment), insured against all loss or damage by
fire with extended coverage in such amount as any first Mortgagee of the
Building may from time to time require.  Tenant shall, throughout the Term, at
its expense, keep Tenant's Special Installations and Alterations and Tenant's
personal property, including any rooftop satellite or antenna dishes and related
equipment, insured against all loss or damage by fire with extended coverage in
an amount sufficient to prevent Tenant from becoming a co-insurer.  Tenant's
policies of insurance shall contain, if available from the insurer, an
appropriate clause or endorsement under which the insurer agrees that such
policy shall not be canceled without at least 30 days notice to Landlord.

          (b)  Notice of Insurance Coverage.  Landlord and Tenant will (i) if
requested, advise the other as to the provisions of fire and extended coverage
insurance policies obtained pursuant to this Section, and (ii) notify the other
promptly of any change in the terms of any such policy which would affect such
provisions.

          (c)  Mutual Waiver of Subrogation

          (i)  Notwithstanding anything to the contrary in this Lease, whether
the loss or damage is due to the negligence of Landlord or Landlord's agents or
employees, or any other cause, Tenant hereby releases Landlord and Landlord's
agents and employees from responsibility for and waives its entire claim of
recovery for (i)

                                      -19-
<PAGE>

any and all loss or damage to the personal property of Tenant located in the
Building (excluding any personal property required to be insured by Landlord
pursuant to the provisions hereof), arising out of any of the perils which are
covered by Tenant's property insurance policy, with extended coverage
endorsements which Tenant is required to obtain under the applicable provisions
of this Lease, whether or not actually obtained.

          (ii)  Notwithstanding anything to the contrary in this Lease, whether
the loss or damage is due to the negligence of Tenant or Tenant's agents or
employees, or any other cause, Landlord hereby releases Tenant and Tenant's
agents and employees from responsibility for and waives its entire claim of
recovery for any and all loss or damage to the Building or any personal property
of Landlord located about the Building and the Building generally and all
property attached thereto (excluding any such property required to be insured by
Tenant hereunder), arising out of any of the perils which are covered by
Landlord's property insurance policy which Landlord is required to obtain under
the applicable provisions of this Lease, whether or not actually obtained.

          (iii) Landlord and Tenant shall each cause its respective property
insurance carrier(s) to consent to such waiver of all rights of subrogation
against the other, and to issue an endorsement to all policies of property
insurance obtained by such party confirming that the foregoing release and
waiver will not invalidate such policies.

          13.   Damage by Fire or Other Casualty.

          In the event of loss of, or damage to, the Leased Premises or the
Building by fire or other casualty, the rights and obligations of the parties
hereto shall be as follows:

          (a)   Repair of Damage.  If the Leased Premises or any part thereof
shall be damaged by fire or other casualty, Tenant shall give prompt notice
thereof to Landlord, and Landlord, upon receiving such notice, shall proceed
promptly and with reasonable diligence, subject to Unavoidable Delays, to
repair, or cause to be repaired, such damage in a manner designed to minimize
interference with Tenant's occupancy (but with no obligation to employ labor at
overtime or other premium pay rates).  If the Leased Premises or any part
thereof shall be rendered untenantable by reason of such damage, whether to the
Leased Premises or the Building, the Basic Rent and Additional Charges shall
proportionately abate with respect thereto for the period from the date of such
damage to the date when such damage shall have been repaired for the portion of
the Leased Premises rendered untenantable.  However, if, prior to the date when
all of such damage shall have been repaired, any part of the Leased Premises is
damaged shall be rendered tenantable and shall be used or occupied by Tenant or
any Person or Persons claiming through or under Tenant, then the amount by which
the Basic Rent and Additional Charges shall abate shall be equitably apportioned
for the period from the date of any such use.

          (b)   Termination of Lease by Landlord or Tenant.  If as a result of
fire or other casualty more than one-half (1/2) of the Leased Premises is
rendered untenantable, Landlord within 60 days from the date of such fire or
casualty may terminate this Lease by notice to Tenant, specifying a date, not
less than 20 nor more than 40 days after the giving of such notice, on which the
Term shall expire as fully and completely as if such date were the date herein
originally fixed for the expiration of the Term.  If the Leased Premises are
damaged as a result of fire or other casualty and if the damage to the Leased
Premises (but not including Tenant's Special Installations or Alterations) is so
extensive that such damage cannot be substantially repaired within 240 days from
the date of the fire or other casualty (except for Unavoidable Delays), either
Landlord or Tenant within 30 days from the date of such fire or other casualty
may terminate this Lease by notice to the other, specifying a date, not less
than 20 nor more than 40 days after the giving of such notice, on which the Term
shall expire as fully and completely as if such date were the date originally
fixed for the expiration of the Term.  If either Landlord or Tenant terminates
this Lease, the Basic Rent and Additional Charges shall be apportioned as of the
date of such fire or other casualty.  If neither Landlord nor Tenant so elects
to terminate this Lease, then Landlord shall proceed to repair the damage to the
Building and the damage to the Leased Premises (but not Tenant's Special
Installations or Alterations), if any shall have occurred, and the Basic Rent
and Additional Charges shall meanwhile be apportioned and abated all as provided
in subsection (a).  However, if such damage is not repaired and the Leased
Premises and the Building

                                      -20-
<PAGE>

restored to reasonably the same condition as they were prior to such damage
within 240 days from the date of such damage (such 240-day period to-be extended
by the period of any Unavoidable Delays), Tenant, within 30 days from the
expiration of such 240-day period (as the same may be extended), may terminate
this Lease by notice to Landlord, specifying a date not more than 60 days after
the giving of such notice on which the Term shall expire as fully and completely
as if such date were the date herein originally fixed for the expiration of the
Term.

          (c)  Termination of Lease by Landlord.  If the Leased Premises shall
be rendered untenantable to the extent of eighty percent (80%) or more by fire
or other casualty during the last six months of the Term, Landlord or Tenant may
terminate this Lease upon notice to the other party given within 90 days after
such fire or other casualty specifying a date, not less than 20 days nor more
than 40 days after the giving of such notice, on which the Term shall expire as
fully and completely as if such date were the date originally fixed for the
expiration of the Term. If either Landlord or Tenant terminates this Lease
pursuant to this subsection, the Basic Rent and Additional Charges shall be
apportioned as of the date of such fire or casualty.

          (d)  Limitation on Landlord's Repair Obligation. Landlord shall not be
required to repair or replace any of Tenant's Special Installations or
Alterations or any other personal property of Tenant and no damages,
compensation or claim shall be payable by Landlord for inconvenience, loss of
business or annoyance arising from any repair or restoration of any portion of
the Leased Premises or of the Building, but the foregoing shall not be deemed to
relieve Landlord of liability for its breach of any covenant of this Lease.

          (e)  Inapplicability of Other Laws.  The provisions of this Section
shall be considered an express agreement governing any instance of damage or
destruction of the Building or the Leased Premises by fire or other casualty,
and any law now or hereafter in force providing for such a contingency in the
absence of express agreement shall have no application.

          (f)  Landlord Released from Liability.  Notwithstanding any other
provision of this Lease, Landlord shall not be liable or responsible for, and
Tenant hereby releases Landlord and its partners, officers, directors, agents
and employees from, any and all liability or responsibility to Tenant or any
Person claiming by, through or under Tenant, by way of subrogation or otherwise,
for any injury, loss or damage to Tenant's property caused by any of the perils
insured against by the fire insurance policy with extended coverage endorsement
which is customarily issued in Fairfax County, Virginia, and Tenant shall
require its insurer(s) to include in all of Tenant's insurance policies which
could give rise to a right of subrogation against Landlord a clause or
endorsement whereby the insurer(s) shall waive any right of subrogation against
Landlord.

          (g)  Tenant Released from Liability.  Notwithstanding any other
provision of this Lease, Tenant shall not be liable or responsible for, and
Landlord hereby releases Tenant and its partners, officers, directors, agents
and employees from, any and all liability or responsibility to Landlord or any
Person claiming by, through or under Landlord, by way of subrogation or
otherwise, for any injury, loss or damage to Landlord's property caused by any
of the perils insured against by the fire insurance policy with extended
coverage endorsement which is customarily issued in Fairfax County, Virginia,
and Landlord shall require its insurer(s) to include in all of Landlord's
insurance policies which could give rise to a right of subrogation against
Tenant a clause or endorsement whereby the insurer(s) shall waive any rights of
subrogation against Tenant.

          (h)  Insurance Proceeds.  The proceeds payable under all fire and
other hazard insurance policies maintained by Landlord on the Building shall
belong to and be the property of Landlord, and Tenant shall not have any
interest in such proceeds. Tenant agrees to look to its own fire and hazard
insurance policies in the event of damage to Tenant's Special Installations or
Alterations or its personal property.

          14.  Condemnation.

          (a)  Effect of Taking. In the event of a Taking of the whole of the
Leased Premises, this Lease shall terminate as of the date of such Taking.  If
only a part of the Leased Premises shall be so taken then,

                                      -21-
<PAGE>

except as otherwise provided in this subsection, this Lease shall continue in
force and effect but, from and after the date of the Taking, the Basic Rent and
Additional Charges shall be reduced on the basis of the square footage of the
portion of the Leased Premises so taken. If a part of the Building shall be
taken, and if either (i) the part of the Building so taken contains more than
twenty-five percent (25%) of the Rentable Area of the Leased Premises,
immediately prior to such Taking, or (ii) in Landlord's reasonable opinion, it
shall be impracticable to continue to operate the Building, then Landlord, at
Landlord's option, may give to Tenant within 60 days after the date upon which
Landlord shall have received notice of the Taking, a 30 days' notice of
termination of this Lease. If a part of the Building shall be taken, and if
either (i) the part of the Building taken contains more than thirty-five percent
(35%) of the Rentable Area of the Leased Premises immediately prior to such
Taking, or (ii) by reason of such Taking, all or substantially all of the Leased
Premises becomes untenantable and Tenant is unable and does not, in fact use all
or substantially all of the Leased Premises for the uses permitted by Section
6(a), then Tenant, at Tenant's option, may give to Landlord within 60 days after
the date upon which Tenant shall have received notice of such Taking, a 30 days'
notice of termination of this Lease. If a 30 days' notice of termination is
given by Landlord or Tenant, this Lease shall terminate upon the expiration of
the 30-day period. If this Lease is terminated pursuant to the foregoing
provisions of this subsection, then, to the extent permitted by applicable law
and such Taking, Tenant shall have access to the Leased Premises in order to
remove Tenant's Special Installations and any other personal property then owned
by Tenant and which Tenant is entitled to remove pursuant to this Lease during
the period of 30 days from the date Tenant is permitted access therefor. If a
Taking occurs which does not result in the termination of this Lease, Landlord
shall repair, alter and restore the remaining portions of the Leased Premises to
their former condition to the extent that the same may be feasible.

          (b)  Award.  Landlord shall have the exclusive right to receive any
and all awards made for damages to the Leased Premises and the Building accruing
by reason of a Taking or by reason of anything lawfully done in pursuance of
public or other authority. Tenant hereby releases and assigns to Landlord all of
Tenant's rights to such awards, and covenants to deliver such further
assignments and assurances thereof as Landlord may from time to time request,
hereby irrevocably designating and appointing Landlord as its attorney-in-fact
to execute and deliver in Tenant's name and behalf all such further assignments
thereof. However, Tenant shall have the right to make its own claim against the
condemning authority for a separate award for the value of any of Tenant's
Special Installations and Alterations, for moving and relocation expenses and
for such business damages and/or consequential damages as may be allowed by law
which do not constitute part of the compensation for the Building and do not
diminish the amount of the award to which Landlord would otherwise be entitled.

          15.  Assignment and Subletting.

          (a)  Subletting to ICF Kaiser International, Inc. It is understood and
agreed that Tenant will sublet the entire Leased Premises to its affiliate, ICF
Kaiser International, Inc., for a basic rent in excess of the Basic Rent payable
hereunder. Upon the written request of Landlord or any Mortgagee following an
event of default under any loan secured by a Mortgage, Tenant shall pay to
Landlord one hundred percent (100%) of the amount of such excess, monthly as
received by Tenant from ICF Kaiser International, Inc.

          (b)  Assignment and Subletting Prohibited.  Tenant shall not mortgage,
pledge, encumber, sell, assign or transfer this Lease, in whole or in part, by
operation of law or otherwise, or sublease all or any part of the Leased
Premises, without Landlord's written consent, which consent may be withheld for
any reason whatsoever except as provided in subsection (a) and subsection (d).
In connection with any request by Tenant for such consent to assign or sublet,
Tenant shall submit to Landlord, in writing, a statement containing the name of
the proposed assignee or subtenant, such information as to its financial
responsibility and standing as Landlord may reasonably require, and all of the
terms and provisions upon which the proposed assignment or subletting is to be
made, and, unless the proposed sublet area shall constitute the entire Leased
Premises, such statement shall be accompanied by a floor plan delineating the
proposed sublet area.  Any attempted transfer, assignment, subletting,
mortgaging or encumbering of this Lease in violation of the provisions of this
Section shall be void and confer no rights upon any third person.  No permitted
assignment or subletting shall relieve Tenant of any of its obligations under
this Lease.

                                      -22-
<PAGE>

          (c)  Merger and Consolidation.  Notwithstanding the provisions of
subsection (b), Tenant shall have the privilege, without the consent of
Landlord, to assign its interest in this Lease to any corporation which is a
successor to Tenant, either by merger or consolidation, or to any corporation
which controls, is controlled by, or is under common control with, the Tenant.
However, no such assignment shall be valid unless, within 10 days after the
consummation thereof, Tenant shall deliver to Landlord (i) a duplicate original
instrument of assignment in form reasonably satisfactory to Landlord, duly
executed by Tenant, and (ii) an instrument in form and substance reasonably
satisfactory to Landlord, duly executed by the assignee, in which such assignee
shall agree to observe and perform, and to be personally bound by, all of the
terms, covenants and conditions of this Lease on Tenant's part to be observed
and performed, whether or not accruing prior to or after the date of such
assignment and whether or not relating to matters arising prior to such
assignment.

          (d)  Permitted Subletting.  Unless an Event of Default has occurred
and is continuing, Landlord shall not unreasonably withhold or delay Landlord's
consent to sublettings by Tenant of a part or parts of the Leased Premises, but
Landlord shall not be obligated to consent to a subletting for a use prohibited
by Section 6(a). Each such subletting shall be for undivided occupancy by the
subtenant of that part of the Floor affected thereby for the use permitted under
this Lease. Landlord may, however, withhold such consent if, in Landlord's
reasonable judgment, the proposed subtenant is not engaged in a business
consistent with the character and dignity of the Building, or will impose any
additional material burden upon Landlord in the operation of the Building (to an
extent greater than the burden to which Landlord would have been put if Tenant
continued to use, or used, such part of the Leased Premises for its own
purposes). In the event of any dispute between Landlord and Tenant as to the
reasonableness of Landlord's refusal to consent to any subletting such dispute
shall be submitted to mediation pursuant to Section 28. Except as otherwise set
forth in subsection (a), if any portion of the Leased Premises is sublet at any
time, and if the rent received by Tenant on account of such subletting exceeds
the Basic Rent, allocated to the space subject to the sublease in the proportion
of the area of such space to the Rentable Area of the Leased Premises, plus
actual out-of-pocket expenses incurred by Tenant in connection with Tenant's
subleasing of such space, including advertising, attorneys' fees, brokerage
commissions and the unamortized cost of preparing such space for occupancy by
the subtenant, then, except as otherwise provided in the next sentence, Tenant
shall pay to Landlord fifty percent (50%) of such excess, monthly as received by
Tenant from the subtenant. Except as otherwise set forth in subsection (a),
Landlord shall not share in any profit derived by Tenant from the permitted
subletting of all or any part of the space located on the Floor designated by
Tenant as its "Sublet Floor" in a notice given to Landlord before Tenant enters
into its first permitted sublease pursuant to this subsection. Notwithstanding
anything to the contrary in this Section 15(d), Tenant shall have the right to
sublet space in the Leased Premises to Tenant's affiliates (hereinafter
defined), subcontractors or consultants without notice to or the consent of
Landlord, and, except as set forth in Section 15(a), without paying any portion
of the profits of such subletting to Landlord. As used herein, a "Tenant's
affiliate" shall mean a corporation or other entity which controls, is
controlled by or is under common control with Tenant, or which is a joint
venture partner of Tenant.

          (e)  Collection of Rent from Assignee.  If Tenant's interest in this
Lease is assigned, whether or not in violation of the provisions of this
Section, Landlord may collect rent from the assignee; if the Leased Premises or
any part thereof are sublet to, or occupied by, or used by, any Person other
than Tenant, whether or not in violation of this Section, Landlord, after
default by Tenant under this Lease, may collect rent from the subtenant, user or
occupant.  In either case, Landlord shall apply the amount collected to the
rents reserved in this Lease, but neither any such assignment, subletting,
occupancy or use, whether with or without Landlord's prior consent, nor any such
collection or application, shall be deemed a waiver of any term, covenant or
condition of this Lease or the acceptance by Landlord of such assignee,
subtenant, occupant or user as tenant.  The consent by Landlord to any
assignment or subletting shall not relieve Tenant from its obligation to obtain
the express prior consent of Landlord to any further assignment or subletting.
The listing of any name other than that of Tenant on any door of the Leased
Premises or on any directory in the Building, or otherwise, shall not operate to
vest in the Person so named any right or interest in this Lease or in the Leased
Premises or be deemed to constitute, or serve as a substitute for, any prior
consent of Landlord required under this Section, and it is understood that any
such listing shall constitute a privilege extended by Landlord which shall be
revocable at Landlord's will by notice to Tenant.  Neither an assignment of
Tenant's interest in this Lease nor a subletting, occupancy or use of the Leased
Premises or any part thereof by any

                                      -23-
<PAGE>

Person other than Tenant as provided in this subsection, nor the application of
any such rent as provided in this subsection shall, in any circumstances,
relieve Tenant from its obligation fully to observe and perform the terms,
covenants and conditions of this Lease on Tenant's part to be observed and
performed.

          16.  Default Provisions.

          (a)  Events of Default.  Each of the following events shall be deemed
to be, and is referred to in this Lease as, an "Event of Default":

          (1)  A default by Tenant in making any payment of Basic Rent or
Additional Charges on the date such payment is due and payable which continues
for more than five days after Landlord shall have given Tenant a written notice
specifying such default; or

          (2)  If, within any period of 12 consecutive months, Landlord has
given two written notices to Tenant pursuant to paragraph (1), a further default
by Tenant, within the 12-month period after the giving of the second such
notice, in making any payment of Basic Rent or Additional Charges on the date
such payment is due which continues for more than 10 days after such payment is
due; or

          (3)  The neglect or failure of Tenant to perform or observe any of the
terms, covenants or conditions contained in this Lease on Tenant's part to be
performed or observed (other than those referred to in paragraph (1) above)
which is not remedied by Tenant (i) within 20 days after Landlord shall have
given to Tenant written notice specifying such neglect or failure, or (ii) in
the case of any such neglect or failure which cannot with due diligence and in
good faith be cured within 20 days, within such additional period, if any, as
may be reasonably required to cure such default with due diligence and in good
faith provided that Tenant commences the curing of the same within the 20-day
period (it being intended that, in connection with any such default which is not
susceptible of being cured with due diligence and in good faith within 20 days,
the time within which the Tenant is required to cure such default shall be
extended for such additional period as may be necessary for the curing thereof
with due diligence and in good faith); or

          (4)  The assignment, transfer, mortgaging or encumbering of this Lease
or the subletting of the Leased Premises in a manner not permitted by Section
15; or

          (5)  The taking of this Lease or the Leased Premises, or any part
thereof, upon execution or by other process of law directed against Tenant, or
upon or subject to any attachment at the instance of any creditor of or claimant
against Tenant, which execution or attachment shall not be discharged or
disposed of within 30 days after the levy thereof.

          (b)  Landlord's Rights Upon Event of Default.  Upon the occurrence of
an Event of Default, Landlord shall have the right, at its election, then or at
any time thereafter while such Event of Default shall continue, either:

          (1)  To give Tenant written notice that this Lease will terminate on a
date to be specified in such notice, which date shall not be less than three
days after such notice if such notice is sent by registered or certified mail,
but which date may be the date of such notice or any date thereafter if such
notice is delivered in person, and on the date specified in such notice Tenant's
right to possession of the Leased Premises shall cease and this Lease shall
thereupon be terminated, but Tenant shall remain liable as provided in
subsection (c); or

          (2)  Without demand or notice, to reenter and take possession of the
Leased Premises, or any part thereof, and repossess the same as of Landlord's
former estate and expel Tenant and those claiming through or under Tenant and
remove the effects of both or either, either by summary proceedings, or by
action at law or in

                                      -24-
<PAGE>

equity, without being deemed guilty of any manner of trespass and without
prejudice to any remedies for arrears of rent or preceding breach of covenant.

          If Landlord elects to re-enter under paragraph (2), Landlord may
terminate this Lease, or, from time to time, without terminating this Lease, may
relet the Leased Premises, or any part thereof, as agent for Tenant for such
term or terms and at such rental or rentals and upon such other terms and
conditions as Landlord may deem advisable, with the right to make alterations
and repairs to the Leased Premises.  No such re-entry or taking of possession of
the Leased Premises by Landlord shall be construed as an election on Landlord's
part to terminate this Lease unless a written notice of such intention is given
to Tenant under paragraph (1) or unless the termination thereof be decreed by a
court of competent jurisdiction.  Tenant waives any right to the service of any
notice of Landlord's intention to reenter provided for by any present or future
law.

          (c) Tenant's Liability for Damages.  If Landlord terminates this Lease
pursuant to subsection (b), Tenant shall remain liable (in addition to accrued
liabilities) to the extent legally permissible for (i) the sum of (A) all Basic
Rent and Additional Charges provided for in this Lease until the date this Lease
would have expired had such termination not occurred, and (B) any and all
reasonable expenses incurred by Landlord in reentering the Leased Premises,
repossessing the same, making good any default of Tenant, painting, altering or
dividing the Leased Premises, combining the same with any adjacent space for any
new tenants, putting the same in proper repair, reletting the same (including
any and all reasonable attorney's fees and disbursements and reasonable
brokerage fees incurred in so doing), and any and all expenses which Landlord
may incur during the occupancy of any new tenant (other than expenses of a type
that are Landlord's responsibility under the terms of this Lease); less (ii) the
proceeds of any reletting.  Tenant agrees to pay to Landlord the difference
between items (i) and (ii) above with respect to each month during the Term, at
the end of such month.  Any suit brought by Landlord to enforce collection of
such difference for any one month shall not prejudice Landlord's right to
enforce the collection of any difference for any subsequent month.  In addition
to the foregoing, Tenant shall pay to Landlord, whether or not the Lease is
terminated, such sums as the court which has jurisdiction thereover may adjudge
reasonable as attorney's fees with respect to any successful law suit or action
instituted by Landlord to enforce the provisions of this Lease.  Landlord shall
have the right, at its sole option, to relet the whole or any part of this
Leased Premises for the whole of the unexpired Term, or longer, or from time to
time for shorter periods, for any rental then obtainable, giving such
concessions of rent and making such special repairs, alterations, decorations
and paintings for any new tenant as Landlord, in its sole and absolute
discretion, may deem advisable.  Tenant's liability as aforesaid shall survive
the institution of summary proceedings and the issuance of any warrant
thereunder.  Landlord shall be under no obligation to relet the Leased Premises,
but agrees to use its best efforts to do so.

          (d) Liquidated Damages.  If Landlord terminates this Lease pursuant to
subsection (b), Landlord shall have the right, at any time, at its option, to
require Tenant to pay to Landlord, on demand, as liquidated and agreed final
damages in lieu of Tenant's liability under subsection (c), an amount equal to
the difference discounted to the date of such demand at an annual rate of
interest equal to the then-current yield on actively traded U.S. Treasury bonds
with 10-year maturities, as published in the Federal Reserve Statistical Release
for the week prior to the date of such termination, between (i) the Basic Rent
and Additional Charges, computed on the basis of the then current annual rate of
Basic Rent and Additional Charges, which would have been payable from the date
of such demand to the date when this Lease would have expired, if it had not
been terminated, and (ii) the then fair rental value of the Leased Premises for
the same period.  Upon exercise of this option by Landlord and payment of such
liquidated and agreed final damages, Tenant shall be released from all further
liability under this Lease with respect to the period after the date of such
demand.  If, after the Event of Default giving rise to the termination of this
Lease, but before presentation of proof of such liquidated damages, the Leased
Premises, or any part thereof, shall be relet by Landlord for a term of one year
or more, the amount of rent reserved upon such reletting shall be deemed to be
the fair rental value for the part of the Leased Premises so relet during the
term of such reletting.

          (e) Rights and Remedies Cumulative.  The rights and remedies herein
conferred are cumulative and not exclusive of any other rights or remedies, and
shall be in addition to every other right, power

                                      -25-
<PAGE>

and remedy that Landlord may have, whether specifically granted herein, or
presently or hereafter existing at law, in equity, or by statute.

          17.  Bankruptcy.

          (a)  Events of Bankruptcy.  The following shall be Events of
Bankruptcy under this Lease: (i) Tenant's becoming insolvent, as that term is
defined in Title 11 of the United States Code (the "Bankruptcy Code"), or under
the insolvency laws of any state, district, commonwealth or territory of the
United States (the "Insolvency Laws"); (ii) the appointment of a receiver or
custodian for any or all of Tenant's property or assets, or the institution of a
foreclosure action upon any of Tenant's real or personal property; (iii) the
filing of a voluntary petition under the provisions of the Bankruptcy Code or
Insolvency Laws; (iv) the filing of an involuntary petition against Tenant as
the subject debtor under the Bankruptcy Code or Insolvency Laws, which either
(A) is not dismissed within sixty (60) days of filing, or (B) results in the
issuance of an order for relief against the debtor; or (iv) Tenant's making or
consenting to an assignment for the benefit of creditors or a common law
composition of creditors.

          (b)  Landlord's Rights Upon Event of Bankruptcy.  Upon the occurrence
of an   Event of Bankruptcy, Landlord shall have all rights and remedies
available to Landlord pursuant to Section 16; provided, however, that while a
case in which Tenant is the subject debtor under the Bankruptcy Code is pending,
Landlord shall not exercise its rights and remedies pursuant to Section 16 so
long as (1) the Bankruptcy Code prohibits the exercise of such rights and
remedies, and (2) Tenant or its Trustee in Bankruptcy (hereinafter referred to
as "Trustee") (i) cures all defaults under this Lease, (ii) compensates Landlord
for monetary damages incurred as a result of such defaults, (iii) provides
adequate assurance of future performance on the part of Tenant as debtor in
possession or on the part of the assignee tenant, and (iv) complies with all
other requirements of the Bankruptcy Code.

          18.  Either Party May Perform the Other's Obligations.

          If Tenant shall fail to keep or perform any of its obligations as
provided in this Lease in respect to (a) maintenance of insurance, (b) repairs
and maintenance of the Leased Premises, (c) compliance with Legal Requirements,
or (d) the making of any other payment or performance of any other obligation,
then Landlord may (but shall not be obligated to do so) upon the continuance of
such failure on Tenant's part for 10 days after written notice to Tenant (or
after such additional period, if any, as Tenant may reasonably require to cure
such failure if of a nature which cannot be cured within said 10 day period), or
without notice in the case of an emergency, and without waiving or releasing
Tenant from any obligation, and as an additional but not exclusive remedy, make
any such payment or perform any such obligation and all sums so paid by Landlord
and all necessary incidental costs and expenses, including attorney's fees,
incurred by Landlord in making such payment or performing such obligation,
together with interest thereon from the date of payment at the Default Interest
Rate, shall be deemed additional rent and shall be paid to Landlord on demand,
or at Landlord's option may be added to any installment of Basic Rent thereafter
falling due, and if not so paid by Tenant, Landlord shall have the same rights
and remedies as in the case of a default by Tenant in the payment of Basic Rent.
If Landlord shall fail to keep or perform any of its obligations as provided in
this Lease in respect to (a) maintenance of insurance, (b) repairs and
maintenance of the Leased Premises, the Building or the common areas, or (c) the
making of any other payment or performance of any other obligation, then Tenant
may (but shall not be obligated to do so) upon the continuance of such failure
on Landlord's part for 10 days after written notice to Landlord (or after such
additional period, if any, as Landlord may reasonably require to cure such
failure if of a nature which cannot be cured within said 10 day period), or
without notice in the case of an emergency, and without waiving or releasing
Landlord from any obligation, and as an additional but not exclusive remedy,
make any such payment or perform any such obligation and all sums so paid by
Tenant and all necessary incidental costs and expenses, including attorney's
fees, incurred by Tenant in making such payment or performing such obligation,
together with interest thereon from the date of payment at the Default Interest
Rate, shall be paid by Landlord to Tenant on demand.

                                      -26-
<PAGE>

          19.  Security Deposit.

          (a)  Use and Application.  Tenant has deposited with Landlord the
Security Deposit, as security for the prompt, full and faithful performance by
Tenant of each and every provision of this Lease and of all obligations of
Tenant hereunder.  Landlord has invested the Security Deposit, and shall keep
the same invested, in (i) prime commercial paper, banker's acceptances or
certificates of deposit in United States commercial banks (having net assets in
excess of $100,000,000), in each case having a maturity of not more than 30
days, or (ii) obligations of the United States Government having a maturity of
not more than 90 days, or (iii) one or more mutual funds which invest their
assets primarily in investment of the type described in clauses (i) and (ii), or
(iv) one or more interest-bearing accounts in financial institutions the
deposits in which are insured by an agency of the United States.  If an Event of
Default occurs, Landlord may use, apply or retain the whole or any part of the
Security Deposit for the payment of (i) any Basic Rent or Additional Charges
which Tenant may not have paid or which may become due after the occurrence of
such Event of Default, (ii) any sum expended by Landlord on Tenant's behalf in
accordance with the provisions of this Lease, or (iii) any sum which Landlord
may expend or be required to expend by reason of Tenant's default, including
damages or deficiency in the reletting of the Leased Premises as provided in
Section 16.  The use, application or retention of the Security Deposit, or any
portion thereof, by Landlord shall not prevent Landlord from exercising any
other right or remedy provided by this Lease or by law and shall not operate as
a limitation on any recovery to which Landlord may otherwise be entitled.  If
any portion of the Security Deposit is used, applied or retained by Landlord for
the purpose set forth above, Tenant agrees, within 10 days after a written
demand therefor is made by Landlord, to deposit cash with the Landlord in an
amount sufficient to restore the Security Deposit to its original amount.

          (b)  Return of Security Deposit.  Provided that Tenant is not then in
default, the Security Deposit, or any balance thereof, and all accrued interest
or gains thereon, shall be returned to Tenant within thirty (30) days after the
expiration of the Term.  In the absence of evidence satisfactory to Landlord of
any permitted assignment of the right to receive the Security Deposit, or the
remaining balance thereof, Landlord may return the same to the original Tenant,
regardless of one or more assignments of Tenant's interest in this Lease or the
Security Deposit.  In such event, upon the return of the Security Deposit (or
balance thereof) to the original Tenant, Landlord shall be completely relieved
of liability under this Section.

          (c)  Return of Accrued Interest on Security Deposit. Within thirty
(30) days after the execution of this Lease by both parties hereto, Landlord
will return all accrued interest on the Security Deposit to Tenant.

          (d)  Transfer of Security Deposit.  In the event of a transfer of
Landlord's interest in the Leased Premises, Landlord shall have the right to
transfer the Security Deposit to the transferee thereof.  In such event, upon
the delivery by Landlord to Tenant of such transferee's written acknowledgment
of its receipt of the Security Deposit, Landlord shall be deemed to have been
released by Tenant from all liability or obligation for the return of the
Security Deposit, and Tenant agrees to look solely to such transferee for the
return of the Security Deposit and the transferee shall be bound by all
provisions of this Lease relating to the return of the Security Deposit.

          (e)  Restrictions on Encumbering.  The Security Deposit shall not be
mortgaged, assigned or encumbered in any manner whatsoever by Tenant without the
prior written consent of Landlord.

          (f)  Letter of Credit. At any time during the Term, Tenant shall have
the right to deliver to Landlord a letter of credit in the amount of the
Security Deposit, to be held by Landlord as security for the performance by
Tenant of all of the obligations to be performed by it under this Lease.  In
such event, Landlord shall refund the cash Security Deposit and all accrued
interest thereon to Tenant within fifteen (15) days after receipt of such letter
of credit.  The letter of credit (and each replacement or renewal thereof) shall
(i) be irrevocable, (ii) be issued by NationsBank, N.A. or another national bank
having an office in Washington, D.C. or Fairfax County, Virginia, which has net
assets of $50,000,000 or more, (iii) be for a term of not less than 12 months
after the date of issuance, and (iv) authorize Landlord to draw thereon by a
sight draft delivered to the issuing bank

                                      -27-
<PAGE>

accompanied by an affidavit of a general partner, or executive officer, of
Landlord that an Event of Default has occurred and is continuing or that Tenant
has failed to deliver a replacement letter of credit within the time required by
this subsection. Tenant shall, on or before the 30th day before the expiration
date of the letter of credit then being held by Landlord under this subsection,
deliver to Landlord an extension or renewal of the letter of credit for a period
of not less than 12 months. Tenant shall extend or renew the letter of credit,
or any extension or renewal thereof, for successive periods of at least 12
months each throughout the Term. Upon the occurrence of an Event of Default or
the Tenant's failure to deliver a replacement letter of credit within the time
required by this subsection, Landlord shall be authorized to draw on the letter
of credit then being held by it. Landlord shall receive, hold and apply the
proceeds of the letter of credit in the same manner and on the same terms as the
Security Deposit. All references in this Lease to the "Security Deposit" shall
be deemed to include the proceeds of the letter of credit.

          20.  Subordination.

          (a)  Mortgages. This Lease and Tenant's interest hereunder shall have
priority over, and be senior to, the lien of any Mortgage made by Landlord after
the date of this Lease.  However, if at any time or from time to time during the
Term, a Mortgagee or prospective Mortgagee requests that this Lease be subject
and subordinate to its Mortgage, this Lease and Tenant's interest hereunder
shall be subject and subordinate to the lien of such Mortgage and to all
renewals, modifications, replacements consolidations and extensions thereof and
to any and all advances made thereunder and the interest thereon.  Tenant agrees
that, within 10 days after receipt of a written request therefor from Landlord,
it will, from time to time, execute and deliver any instrument or other document
required by any such  Mortgagee to subordinate this Lease and its interest in
the Leased Premises to the lien of such Mortgage.  If, at any time or from time
to time during the Term, a Mortgagee of a Mortgage made prior to the date of
this Lease shall request that this Lease have priority over the lien of such
Mortgage, and if Landlord consents thereto, this Lease shall have priority over
the lien of such Mortgage and all renewals, modifications, replacements,
consolidations and extensions thereof and all advances made thereunder and the
interest thereon, and Tenant shall, within 10 days after receipt of a written
request therefor from Landlord, execute, acknowledge and deliver any and all
documents and instruments confirming the priority of this Lease.  In any event,
however, if this Lease shall have priority over the lien of a Mortgage, this
Lease shall not become subject or subordinate to the lien of any subordinate
Mortgage, and Tenant shall not execute any subordination documents or
instruments for any subordinate Mortgagee, without the written consent of the
prior Mortgagee.

          (b)  Ground Leases.  This Lease and Tenant's interest hereunder shall
be subject and subordinate to each and every ground or underlying lease
hereafter made of the Building or the land on which it is constructed, or both,
and to all renewals, modifications, replacements and extensions thereof.  Tenant
agrees that, within 10 days after receipt of written request therefor from
Landlord, it will, from time to time, execute, acknowledge and deliver any
instrument or other document required by any such lessor to subordinate this
Lease and its interest in the Leased Premises to such ground or underlying
lease.

          (c)  First Mortgagee's Right of Cure.  If (i) the Building, or any
part thereof, or the land on which the Building is constructed, or the
Landlord's leasehold estate in the Building, is at any time subject to a first
Mortgage, and (ii) this Lease, or the Basic Rent and Additional Charges payable
under this Lease, is assigned to the first Mortgagee, and (iii) the Tenant is
given written notice of such assignment, including the name and address of the
assignee, then, in that event, Tenant shall not terminate this Lease or make any
abatement in the Basic Rent payable hereunder for any default on the part of the
Landlord without first giving written notice, in the manner provided elsewhere
in this Lease for the giving of notices, to such first Mortgagee, specifying the
default in reasonable detail, and affording such first Mortgagee a reasonable
opportunity to make performance, at its election, for and on behalf of the
Landlord.

          (d)  Non-Disturbance Agreement.  Notwithstanding the provisions of
subsections (a) and (b), neither this Lease nor any right, title or interest of
Tenant in the Leased Premises shall be subordinate to the lien of any ground or
underlying lease

                                      -28-
<PAGE>

or any Mortgage made or placed after the date of this Lease, and Tenant shall
not be required to subordinate this Lease or Tenant's interest in the Leased
Premises to any such ground or underlying lease or any such Mortgage, unless
such lease or Mortgage contains an express provision (or the lessor or the
Mortgagee or other party secured by the Mortgage agrees in writing) to the
effect that so long as this Lease has not been terminated by reason of the
occurrence of an Event of Default, the lessor or the Mortgagee (or other party
secured by the Mortgage) will be bound by all of the terms and provisions of
this Lease (except as otherwise set forth in such agreement), a default by the
Landlord under such lease or by the mortgagor under such Mortgage shall not have
any effect upon Tenant's right to occupy the Leased Premises in accordance with
all of the terms and conditions of this Lease, and the term, estate and options
of Tenant under this Lease shall not be terminated or otherwise affected by a
termination of such ground or underlying lease or a foreclosure and sale or
other action instituted under or in connection with such Mortgage.
Contemporaneously with the execution of this Lease, Landlord shall deliver to
Tenant a non-disturbance agreement, in form reasonably satisfactory to Tenant,
from the Mortgagee under any existing Mortgage, to the effect that so long as
this Lease has not been terminated by reason of the occurrence of an Event of
Default, the Mortgagee (or other party secured by the Mortgage) will be bound by
all of the terms and provisions of this Lease, a default by the mortgagor under
such Mortgage shall not have any effect upon Tenant's right to occupy the Leased
Premises in accordance with all of the terms and conditions of this Lease, and
the term, estate and options of Tenant under this Lease shall not be terminated
or otherwise affected by a foreclosure and sale or other action instituted under
or in connection with such Mortgage. Contemporaneously with the execution of
this Agreement, Landlord shall deliver to Tenant a non-disturbance agreement, in
form reasonably satisfactory to Tenant, from the lessor under the Ground Lease,
to the effect that so long as this Lease has not been terminated by reason of
the occurrence of an Event of Default, the lessor will be bound by all of the
terms and provisions of this Lease, a default by the Landlord under such Ground
Lease shall not have any effect upon Tenant's right to occupy the Leased
Premises in accordance with all of the terms and conditions of this Lease, and
the term, estate and options of Tenant under this Lease shall not be terminated
or otherwise affected by a termination of such Ground Lease.

          21.  Attornment.

          In the event of (a) a transfer of Landlord's interest in the Leased
Premises, (b) the termination of any ground or underlying lease of the Building
or the land on which it is constructed, or both, or (c) the purchase of the
Building or Landlord's interest therein in a foreclosure sale or by deed in lieu
of foreclosure under any Mortgage or pursuant to a power of sale contained in
any Mortgage, then in any of such events Tenant shall, at Landlord's request,
attorn to and recognize the transferee or purchaser of Landlord's interest or
the lessor under the terminated ground or underlying lease, as the case may be,
as Landlord under this Lease for the balance then remaining of the Term, and
thereafter this Lease shall continue as a direct lease between such person, as
"Landlord,"  and Tenant, as "Tenant,"  except that such lessor, transferee or
purchaser shall not be liable for any act or omission of Landlord prior to such
lease termination or prior to such person's succession to title, nor be subject
to any offset, defense or counterclaim accruing prior to such lease termination
or prior to such person's succession to title, nor be bound by any payment of
Basic Rent or Additional Charges prior to such lease termination or prior to
such person's succession to title for more than one month in advance.  Tenant
shall, upon request by Landlord or the transferee or purchaser of Landlord's
interest or the lessor under the terminated ground or underlying lease, as the
case may be, execute and deliver an instrument or instruments confirming the
foregoing provisions of this Section.  Tenant hereby waives the provisions of
any present or future law or regulation which gives or purports to give Tenant
any right to terminate or otherwise adversely affect this Lease, or the
obligations of Tenant hereunder, upon or as a result of the termination of any
such ground or underlying lease or the completion of any such foreclosure and
sale.

          22.  Quiet Enjoyment.

          Landlord covenants that Tenant, upon paying the Basic Rent and the
Additional Charges provided for in this Lease, and upon performing and observing
all of the terms, covenants, conditions and provisions of this Lease on Tenant's
part to be kept, observed and performed, shall quietly hold, occupy and enjoy
the Leased Premises during the Term without hindrance, ejection or molestation
by Landlord or any party lawfully claiming through or under Landlord.

                                      -29-
<PAGE>

          23.  Landlord's Right of Access to Leased Premises.

          (a)  Right of Entry.  Landlord and its agents shall have the following
rights in and about the Leased Premises: (i) to enter the Leased Premises at all
reasonable times to examine the Leased Premises or for any of the purposes set
forth in this Section or for the purpose of performing any obligation of
Landlord under this Lease or exercising any right or remedy reserved to Landlord
in this Lease, and if Tenant, its officers, partners, agents or employees shall
not be personally present or shall not open and permit an entry into the Leased
Premises at any time when such entry shall be necessary or permissible, to use a
master key or forcibly to enter the Leased Premises; (ii) to erect, install, use
and maintain pipes, ducts and conduits in and through the Leased Premises which,
when completed, will not substantially interfere with the use or appearance or
materially reduce the space afforded to Tenant in the Leased Premises; (iii) to
exhibit the Leased Premises to others at reasonable times and for reasonable
purposes; (iv) to make such repairs, alterations or improvements, or to perform
maintenance of all heating, air-conditioning, elevator, plumbing, electrical and
other mechanical facilities installed by Landlord, as may be required from time
to time by this Lease to be made or performed by Landlord; (v) to take all
materials into and upon the Leased Premises that may be required in connection
with any such repairs, alterations, improvements or maintenance; and (vi) to
alter, renovate and decorate the Leased Premises at any time during the Term if
Tenant shall have removed all or substantially all of Tenant's property from the
Leased Premises.  Landlord agrees to give prior notice before it exercises its
rights under this subsection, except that Landlord may enter the Leased Premises
without notice in the case of an emergency.  In making such an entry,  Landlord
agrees to use reasonable efforts to avoid interfering with the regular and usual
conduct of the Tenant's business.  Notwithstanding anything to the contrary
herein, Landlord may obtain access to the double-secured areas of the Leased
Premises only with the permission and assistance of Tenant's Director of
Facilities, except in the event of an emergency posing a threat of immediate
injury to persons or property.

          (b)  Rights in Adjacent Areas.  Except as otherwise provided in
Section 10, all parts (except surfaces facing the interior of the Leased
Premises) of all walls, windows and doors bounding the Leased Premises
(including exterior Building walls, corridor walls, doors and entrances), all
balconies, terraces and roofs adjacent to the Leased Premises, all space in or
adjacent to the Leased Premises used for shafts, stacks, stairways, chutes,
pipes, conduits, ducts, fan rooms, heating, air-conditioning, plumbing,
electrical and other mechanical facilities installed by Landlord, service
closets and other Building facilities, and the use thereof, as well as access
thereto through the Leased Premises for the purposes of operation, maintenance,
alteration and repair, are hereby reserved to Landlord. Nothing contained in
this Section shall impose any obligation upon Landlord with respect to the
operation, maintenance, alteration or repair of the Leased Premises or the
Building.

          (c)  Effect of Landlord's Entry.  The exercise by Landlord or its
agents of any right reserved to Landlord in this Section shall not constitute an
actual or constructive eviction, in whole or in part, or entitle Tenant to any
abatement or diminution of rent, or relieve Tenant from any of its obligations
under this Lease, or impose any liability upon Landlord, or its agents, or upon
any lessor under any ground or underlying lease, by reason of inconvenience or
annoyance to Tenant, or injury to or interruption of Tenant's business, or
otherwise.  Landlord agrees to exercise its rights under this Section in a
manner designed to minimize interference with Tenant's normal business
operations, without any obligation, however, to employ labor at overtime or
other premium pay rates.

          24.  Limitation on Landlord's Liability.

          (a)  Accidents, etc.  Except for damages resulting from the willful or
negligent act or omission of Landlord, its agents, employees or contractors,
Landlord shall not be liable to Tenant, its employees, agents, business
invitees, licensees, customers, guests or trespassers, for any damage or loss to
the property of Tenant or others located on the Leased Premises, or in the
Building or the land on which it is built, or for any accident or injury to
Persons in the Leased Premises or the Building, resulting from the necessity of
repairing any portion of the Building; the use or operation (by Tenant or any
other Person or Persons whatsoever) of any elevators, or heating, cooling,
electrical or plumbing equipment or apparatus; the termination of this Lease by

                                      -30-
<PAGE>

reason of the destruction of the Building or the Leased Premises; any fire,
robbery, theft, and/or any other casualty; any leaking in any part or portion of
the Leased Premises or the Building; any water, wind, rain, or snow that may
leak into, or flow from, any part of the Leased Premises or the Building; any
acts or omissions of any occupant of any space adjacent to or adjoining all or
any part of the Leased Premises; any water, gas, steam, fire, explosion,
electricity or falling plaster; the bursting, stoppage or leakage of any pipes,
sewer pipes, drains, conduits, appliances or plumbing works; or any other cause
whatsoever.

          (b) Unavoidable Delays.  Neither Landlord nor Tenant shall be required
to perform any of its obligations under any provision of this Lease, or be
liable for loss or damage for failure to do so, nor shall the other party be
released from any of its obligations under this Lease because of such party's
failure to perform, where such failure arises from or through Unavoidable Delays
or Legal Requirements.  If Landlord or Tenant is so delayed or prevented from
performing any of its obligations during the Term, the period of such delay or
such prevention shall be deemed added to the time herein provided for the
performance of any such obligation.  Lack of funds shall not be deemed an
Unavoidable Delay for purposes of this Section 24(b), and nothing in this
Section 24(b) shall excuse Tenant's failure to promptly pay any Basic Rent or
Additional Charges due under this Lease, or Landlord's or Tenant's failure to
maintain policies or deliver certificates of insurance required hereunder.

          (c) Building Services.  If Landlord shall fail to supply, or be
delayed in applying, any service expressly or impliedly to be supplied under
this Lease, or shall be unable to make, or be delayed in making, any repairs,
alterations, additions, improvements or decorations, or shall be unable to
supply, or be delayed in supplying, any equipment or fixtures, and if such
failure, delay or inability shall result from Unavoidable Delays, such failure,
delay or inability shall not constitute an actual or constructive eviction, in
whole or in part, or relieve Tenant from any of its obligations under this
Lease, or impose any liability upon Landlord or its agents by reason of
inconvenience to Tenant, or injury to, or interruption of, Tenant's business, or
otherwise, or entitle Tenant to any abatement or diminution of rent except as
provided in Section 3(i).

          (d) Liability Limited to Landlord's Estate.  Notwithstanding any
provision to the contrary, Tenant shall look solely to the estate and property
of Landlord in and to the Building (or the proceeds received by Landlord on a
sale of such estate and property but not the proceeds of any financing or
refinancing thereof) in the event of any claim against Landlord arising out of
or in connection with this Lease, the relationship of Landlord and Tenant or
Tenant's use of the Leased Premises, and Tenant agrees that the liability of
Landlord arising out of or in connection with this Lease, the relationship of
Landlord and Tenant or Tenant's use of the Leased Premises, shall be limited to
such estate and property of Landlord (or sale, insurance or condemnation
proceeds in connection therewith).  No other properties or assets of Landlord
shall be subject to levy, execution or other enforcement procedures for the
satisfaction of any judgment (or other judicial process) or for the satisfaction
of any other remedy of Tenant arising out of or in connection with this Lease,
the relationship of Landlord and Tenant or Tenant's use of the Leased Premises,
and if Tenant shall acquire a lien on or interest in any other properties or
assets by judgment or otherwise, Tenant shall promptly release such lien on or
interest in such other properties and assets by executing, acknowledging and
delivering to Landlord an instrument to that effect prepared by Landlord's
attorneys.

          25. Estoppel Certificates.

          Tenant and Landlord each agrees, from time to time, within 15 days
after written request therefor by the other party, to execute, acknowledge and
deliver to the other party a statement in writing certifying to the other party,
any Mortgagee, assignee of a Mortgagee, or any purchaser, of the Building or the
land on which it is constructed, or both, or any other Person designated by the
other party, as of the date of such statement, (i) that Tenant is in possession
of the Leased Premises; (ii) that this Lease is unmodified and in full force and
effect (or, if there have been modifications, that this Lease is in full force
and effect as modified and setting forth such modifications);  (iii) whether or
not there are then existing any set-offs or defenses known to such party against
the enforcement of any right or remedy of the other party, or any duty or
obligation of such party, hereunder (and, if so, specifying the same in detail);
(iv) the dates, if any, to which any Basic Rent or Additional Charges have been
paid in advance; (v) that such party has no knowledge of any uncured defaults on
the part of the other party under this Lease (or, if such party has knowledge of
any such uncured defaults, specifying the same in detail); (vi) that such

                                      -31-
<PAGE>

party has no knowledge of any event having occurred that authorizes the
termination of this Lease by such party (or, if such party has such knowledge,
specifying the same in detail); (vii) the amount of any Security Deposit held by
Landlord; and (viii) any additional facts reasonably requested by any such
Mortgagee, assignee of a Mortgagee, purchaser or other Person.

          26.  Surrender of Leased Premises.

          (a)  Possession.  Tenant shall, on or before the last day of the Term,
except as otherwise expressly provided elsewhere in this Lease, remove all of
its property and peaceably and quietly leave, surrender and yield up to the
Landlord the Leased Premises, free of subtenancies, broom clean and in good
order and condition except for reasonable wear and tear, damage by fire or other
casualty, or conditions requiring repair by Landlord hereunder at Landlord's
expense.

          (b)  Inspection of Leased Premises.  At the time Tenant surrenders the
Leased Premises at the end of the Term, or within twenty (20) days thereafter,
Landlord and Tenant, or their respective agents, shall inspect the Leased
Premises and shall prepare and sign an inspection form to describe the condition
of the Leased Premises at the time of surrender.

          (c)  Survival.  The provisions of this Section shall survive any
expiration or termination of this Lease.

          27.  Holding Over.

          If Tenant shall hold over possession of the Leased Premises after the
end of the Term, Tenant shall be deemed to be occupying the Leased Premises as a
Tenant from month to month, at one hundred fifty percent (150%) of the Basic
Rent, adjusted to a monthly basis, and subject to all the other conditions,
provisions and obligations of this Lease insofar as the same are applicable, or
as the same shall be adjusted, to a month-to-month tenancy.

          28.  Mediation.

          In any case in which it is provided by the terms of this Lease that
any matter shall be determined by mediation, then such mediation shall be in
accordance with the Commercial Mediation Rules then in effect of the American
Arbitration Association ("AAA"). The mediation proceeding shall be conducted in
Washington, D.C., by one mediator selected by the AAA.  The cost of the
mediation, including filing fees with the AAA and the cost of the mediator,
shall be borne equally by the parties.  In the mediation sessions, the parties
shall endeavor in good faith to resolve the claim or controversy at issue.  Any
party or the mediator shall have the right to terminate the mediation at any
time after the first mediation session.  Neither party may make any disclosure
of the existence or results of the mediation without the prior written consent
of the other party.  The mediator may not make any disclosure of the existence
or results of the mediation without the prior written consent of both parties.
No discussions in the mediation shall be admissible in any litigation between
the parties, and the mediator shall not be subject to subpoena to testify to any
communication between the mediator and either party.  If the parties are unable
to settle the matter by mediation, then either party may submit such matter to
litigation.

          29.  Parking.

          Throughout the Term, Tenant shall be entitled to the use of 334
parking spaces in the structured parking facility for the Office Park (the
"Parking Spaces"), without additional charge therefor.  The Parking Spaces shall
be available to Tenant and/or its employees on an unreserved basis, in common
with the other tenants of the Office Park.  If at any time Tenant leases any
additional space in the Building, Tenant shall be entitled, without charge, to
the use of one additional parking space in such parking facility for each 297
square feet of net rentable area of such space.

                                      -32-
<PAGE>

          30.  Renewal of Term.

          Provided that this Lease shall be in full force and effect and that
Tenant shall not then be in default, Tenant shall have the right, at Tenant's
sole option, to extend the Lease for one (1) consecutive additional period of
five (5) years (such additional period being hereinafter referred to as the
"Renewal Period", if exercised, and included in the definition of the Term).
Such option to extend shall be exercised by Tenant giving written notice of the
exercise to Landlord at least twenty-four (24) months prior to the expiration of
the Initial Term of this Lease.  The Renewal Period shall be for the same Basic
Rent payable during the last Lease Year of the Initial Term, escalated at the
commencement of the Renewal Period and at the commencement of each Lease Year
thereafter by the Inflation Adjustment, and upon the same terms, covenants and
conditions set forth in this Lease with respect to the Initial Term, and
Tenant's obligations to pay Operating Expense Increases pursuant to Section 3(b)
shall continue without interruption during the Renewal Period.  In the event
Tenant defaults beyond any applicable cure period under this Lease after
providing notice of exercise of its renewal option but prior to the expiration
of the Initial Term, such exercise shall, at Landlord's option exercised by
written notice to Tenant, be void ab initio.

          31.  Shuttle Service.

          Landlord shall provide for Tenant' s employees, other tenants of the
Building and other adjacent buildings owned by Landlord or its affiliates, and
the employees of such other tenants a private shuttle bus service between the
Building and the Vienna Metro Station. Subject to Unavoidable Delays, the
shuttle bus service shall be provided throughout the Term and continuously
during the hours between 7:00 a.m. and 8:00 p.m. on Business Days.  Landlord
shall use shuttle buses which have reasonably adequate seating capacity taking
into account average passenger usage from time to time.  Landlord shall provide
private shuttle bus service for Tenant's employees at times in addition to those
specified in this Section, at Tenant's expense, as mutually agreed upon by
Landlord and Tenant.  Landlord shall charge Tenant for after-hours service at an
hourly rate from time to time established by Landlord, in its sole discretion,
but in no event will the rate per hour charged to Tenant be more than an amount
per hour which represents Landlord's reasonable estimate of its actual cost of
providing such after-hours service, including labor, cost of fuel, and wear and
tear on equipment, plus an allowance of 10% thereof to cover general overhead.
In the event the same after-hours service is also requested by other tenants of
the Building (or any other building owned by Landlord or its affiliates) in
addition to Tenant, the charge therefor to each tenant requesting such after-
hours service shall be a pro-rated amount based upon the net rentable area of
the leased premises of all tenants requesting such after-hours service.  Payment
for such charges shall be due and payable to Landlord within 15 days after
Tenant's receipt of an invoice therefor.  Any dispute between Landlord and
Tenant with respect to the adequacy of Landlord's shuttle bus service shall be
submitted to mediation pursuant to Section 28.

          32.  Leasing Commission.

          Landlord and Tenant each represent and warrant to the other that
neither of them has employed any broker, other than The Carey Winston Company,
in carrying on the negotiations relative to this Lease.  Tenant shall pay any
commission due The Carey Winston Company in connection with this Lease.
Landlord and Tenant shall each indemnify and hold harmless the other from and
against any claim or claims for brokerage or other commission arising from or
out of any breach of the foregoing representation and warranty.

          33.  General Provisions.

          (a)  Binding Effect.  The covenants, conditions, agreements, terms and
provisions herein contained shall be binding upon, and shall inure to the
benefit of, the parties hereto and, subject to the provisions of Section 15,
each of their respective personal representatives, successors and assigns.

                                      -33-
<PAGE>

          (b)  Governing Law.  It is the intention of the parties hereto that
this Lease (and the terms and provisions hereof) shall be construed and enforced
in accordance with the laws of the State of Virginia.

          (c)  Waivers.  No failure by Landlord to insist upon the strict
performance of any term, covenant, agreement, provision, condition or limitation
of this Lease or to exercise any right or remedy consequent upon a breach
thereof, and no acceptance by the Landlord of full or partial rent during the
continuance of any such breach, shall constitute a waiver of any such breach or
of any such term, covenant, agreement, provision, condition or limitation.  No
term, covenant, agreement, provision, condition or limitation of this Lease to
be kept, observed or performed by Landlord or by Tenant, and no breach thereof,
shall be waived, altered or modified except by a written instrument executed by
Landlord or by Tenant, as the case may be.  No waiver of any breach shall affect
or alter this Lease, but each and every term, covenant, agreement, provision,
condition and limitation of this Lease shall continue in full force and effect
with respect to any other then existing or subsequent breach thereof.

          (d)  Notices.  No notice, request, consent, approval, waiver or other
communication which may be or is required or permitted to be given under this
Lease shall be effective unless the same is in writing and is delivered in
person or sent by registered or certified mail, return receipt requested, first-
class postage prepaid, (1) if to Landlord, at Landlord's Notice Address, or (2)
if to Tenant, at Tenant's Notice Address, or at any other address that may be
given by one party to the other by notice pursuant to this subsection.  Such
notices, if sent by registered or certified mail, shall be deemed to have been
given at the time of mailing.

          (e)  Entire Agreement.  It is understood and agreed by and between the
parties hereto that this Lease contains the final and entire agreement between
said parties, and that they shall not be bound by any terms, statements,
conditions or representations, oral or written, express or implied, not herein
contained.  It is understood and agreed, however, that the terms hereof shall be
modified, if so required, for the purpose of complying with or fulfilling the
requirements of any Mortgagee secured by a first Mortgage that may now be or
hereafter become a lien on the Building, provided, however, that such
modification shall not be in substantial derogation or diminution of any of the
rights of the parties hereunder, nor increase any of the obligation or
liabilities of the parties hereunder.

          (f)  Jury Trial.  Landlord and Tenant each hereby waives all right to
trial by jury in any claim, action, proceeding or counterclaim by either
Landlord or Tenant against the other on any matters arising out of or in any way
connected with this Lease, the relationship of Landlord and Tenant and/or
Tenant's use or occupancy of the Leased Premises.

          (g)  Venue.  Tenant hereby waives any objection to the venue of any
action filed by Landlord against Tenant in any state or federal court in the
jurisdiction in which the Building is located, and Tenant further waives any
right, claim or power, under the doctrine of forum non conveniens or otherwise,
to transfer any such action filed by Landlord to any other court.

          (h)  Corporate Authority. Concurrently with the signing of this Lease,
Tenant shall furnish to Landlord certified copies of the resolutions of its
Board of Directors (or of the executive committee of its Board of Directors)
authorizing Tenant to enter into this Lease; and Tenant shall also furnish to
Landlord evidence (reasonably satisfactory to Landlord and its counsel) that
Tenant is a duly organized corporation in good standing under the laws of the
jurisdiction of its incorporation, is qualified to do business in good standing
in the State of Virginia, has the power and authority to enter into this Lease,
and that all corporate action requisite to authorize Tenant to enter into this
Lease has been duly taken.

          (i)  Time of the Essence.  Time is of the essence in the performance
of Landlord's and Tenant's obligations under this Lease.

          (j)  Gender.  Wherever appropriate herein, the singular includes the
plural and the plural includes the singular.

                                      -34-
<PAGE>

          (k) Invalidity.  If any provision of this Lease shall be invalid,
illegal or unenforceable, the validity, legality and enforceability of the
remaining provisions shall not be affected thereby.

          (1) Captions.  The captions in this Lease are for convenience only and
shall not affect the interpretation of the provisions hereof.

          (m) No Partnership.  This Lease is not intended to create a
partnership or joint venture between Landlord and Tenant in the conduct of their
respective businesses.

          (n) Counterparts.  This Lease has been executed in several
counterparts, but all counterparts shall constitute one and the same instrument.

          (o) Deed of Lease.  To the extent required under applicable law to
make this Lease legally effective, this Lease shall constitute a deed of lease.

          34. Termination of Prior Lease.

          This Lease entirely supersedes the Lease Agreement dated April 27,
1988, as amended by the First Amendment, the Second Amendment and the Third
Amendment, and the Lease Agreement dated April 27, 1988, as amended, is hereby
terminated.

          IN WITNESS WHEREOF, Landlord and Tenant have caused this Lease to be
signed by their duly authorized partners or officers as of the day and year
first above written.

                                    Landlord

                                    HMCE ASSOCIATES LIMITED
                                    PARTNERSHIP, R.L.L.P.


                                    By   /s/ David W. Evans
                                         ----------------------------


                                    Tenant


                                    ICF KAISER HUNTERS BRANCH LEASING,
                                    INC.


                                    By   /s/ Timothy P. O'Commor
                                         ----------------------------

                                      -35-