<PAGE>

                                                                    EXHIBIT 10.7

                           PURCHASE AND SALE AGREEMENT

                                     BETWEEN

                   ARMADA/HOFFLER INVESTMENT PROPERTIES, L.P.
                                    "SELLER"

                                       AND

                           COLUMBIA EQUITY TRUST, INC.
                                   "PURCHASER"

<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                         PAGE
                                                                         ----
<S>  <C>                                                                 <C>
1.   Purchase and Sale of the Property..............................       1
2.   Purchase Price and Method of Payment...........................       2
     2.1 Purchase Price.............................................       2
     2.2 Method of Payment..........................................       2
     2.3 Deposit....................................................       2
3.   Seller's Representations and Warranties........................       3
     3.1 Organization and Authority.................................       3
     3.2 Noncontravention...........................................       3
     3.3 Consents...................................................       3
     3.4 Ownership..................................................       4
     3.6 Condemnation...............................................       4
     3.7 Litigation or Proceedings..................................       4
     3.8 Compliance; Notice of Violations...........................       4
     3.9 Liens......................................................       4
     3.10 Lease.....................................................       5
     3.11 Service Contracts.........................................       5
     3.12 No Actions................................................       5
     3.13 Existing Indebtedness.....................................       5
     3.14 Absence of Bankruptcy.....................................       6
     3.15 Driveways and Access......................................       6
     3.16 Utilities.................................................       6
     3.17 Underground Storage Tanks.................................       6
     3.18 Property Information......................................       6
     3.19 Lease Guaranty............................................       6
     3.20 Deed Restriction/Purchase Option..........................       6
     3.21 Zoning....................................................       6
4.   Purchaser's Representations and Warranties.....................       7
     4.1 Organization and Authority.................................       7
     4.2 Noncontravention...........................................       8
     4.3 Litigation or Proceedings..................................       8
     4.4 Consents...................................................       8
5.   Inspection; Condition of Property and Title....................       8
     5.1 Right of Inspection........................................       8
     5.2 Inspection Period..........................................       9
     5.3 "As-Is and Where Is Condition".............................      10
     5.4 Title Examination..........................................      10
     5.5 Assumption of Existing Indebtedness........................      10
6.   Conditions Precedent to Closing................................      10
     6.1 Purchaser's Conditions Precedent to Closing................      10
     6.2 Failure of Condition to Purchaser's Obligations............      12
</TABLE>

                                       ii
<PAGE>

                               TABLE OF CONTENTS
                               -----------------
                                   CONTINUED...

<TABLE>
<CAPTION>
                                                                        PAGE
                                                                        ----
<S>  <C>                                                                <C>
7.   Closing........................................................      12
8.   Seller's Deliveries............................................      13
     8.1 Deed                                                             13
     8.2 Assignment of Lease and Service Contracts..................      13
     8.3 Seller's Affidavits........................................      13
     8.4 FIRPTA Affidavit...........................................      13
     8.5 Resolutions................................................      13
     8.6 Bill of Sale...............................................      13
     8.7 Possession; Keys...........................................      14
     8.8 Original Documents.........................................      14
     8.9 Files......................................................      14
     8.10 Notice of Sale............................................      14
     8.11 Termination of Management Agreement.......................      14
     8.12 Termination of Leasing Agreement..........................      14
     8.13 General Ledgers...........................................      14
     8.14 Other Documents...........................................      14
9.   Purchaser's Closing Obligations................................      14
10.  Settlement Charges; Prorations and Adjustments.................      14
     10.1 Allocation of Settlement Charges..........................      14
     10.2 Prorations and Adjustments................................      14
     10.3 Release of Closing Escrow.................................      16
11.  Condemnation and Risk of Loss..................................      16
12.  Default Provisions; Remedies...................................      16
     12.1 Purchaser's Default.......................................      17
     12.2 Seller's Default..........................................      17
13.  Obligations of Seller Pending Closing..........................      17
     13.1 Occupancy at Closing......................................      17
     13.2 Leasing...................................................      17
     13.3 Maintenance and Operation of Property.....................      18
     13.4 No Action.................................................      18
     13.5 Additional Deliveries.....................................      18
     13.6 Scheduled Payments of the Existing Indebtedness...........      18
14.  Miscellaneous Provisions.......................................      18
     14.1 Completeness and Modification.............................      18
     14.2 Additional Documents......................................      18
     14.3 Severability..............................................      18
     14.4 Cumulative Remedies.......................................      18
     14.5 Construction..............................................      19
     14.6 Pronouns..................................................      19
     14.7 Binding Effect; Assignment................................      19
     14.8 Waiver; Modification......................................      19
     14.9 Governing Law.............................................      19
</TABLE>

                                      iii
<PAGE>

                               TABLE OF CONTENTS
                               -----------------
                                   CONTINUED...

<TABLE>
<CAPTION>
                                                                        PAGE
                                                                        ----
<S>  <C>                                                                <C>
     14.10 Headings.................................................      19
     14.11 Exhibits.................................................      19
     14.12 Counterparts.............................................      19
     14.13 Notices..................................................      19
     14.14 Section 1031 Exchange....................................      20
     14.15 Business Day.............................................      20
     14.16 Survival.................................................      20
     14.17 Attorneys' Fees..........................................      20
     14.18 Waiver of Jury...........................................      21
     14.19 Brokerage Commission.....................................      21
     14.20 Confidentiality..........................................      21
     14.21 Standstill Period........................................      21
</TABLE>

                                       iv
<PAGE>

                           PURCHASE AND SALE AGREEMENT

      THIS PURCHASE AND SALE AGREEMENT ("AGREEMENT") is made and entered into as
of the 15th day of March, 2006, by and between ARMADA/HOFFLER INVESTMENT
PROPERTIES, L.P., a Virginia limited partnership ("SELLER"), and COLUMBIA EQUITY
TRUST, INC., a Maryland corporation, or its permitted assigns (collectively
"PURCHASER").

                                R E C I T A L S:

      A. Seller is the fee simple owner of that certain real property located in
Reston, County of Fairfax, Virginia consisting of certain improvements known by
street address 1741 Business Center Drive, Reston, Virginia 20190 comprising
approximately 207,725 square feet of land and containing approximately 41,357
net rentable square feet of office space in a building (the "Building") located
in the Lake Fairfax Business Center, such real property being more particularly
described on Exhibit A attached hereto; and all right, title and interest of
Seller, if any, that is appurtenant to the real property described on Exhibit A
in and to the following: any land lying in the bed of any existing, dedicated
street, road or alley, all strips and gores adjoining thereto and all
appurtenances, rights, easements, rights-of-way, covenants, tenements,
hereditaments and other rights incident thereto, including, without limitation,
any right or option to acquire or benefit from any future easement or
right-of-way to the extent that such rights and interests may benefit such real
property (collectively, the "LAND"), together with all improvements situated
thereon and all right, title and interest of Seller in and to all other
improvements, driveways, landscaping, paving, walkways, plumbing and heating
pipes and fixtures situated thereon that they may benefit such improvements,
situated thereon and/or used in connection therewith to the extent that they may
benefit such improvements (collectively, the "IMPROVEMENTS"), and, to the extent
assignable, any leases, contract rights, escrow or security deposits, utility
agreements, guarantees, licenses, approvals, amounts held in reserve by the
holder of the Existing Indebtedness (defined below) with respect to the
Improvements; certificates of occupancy, plans and specifications, logos,
permits, warranties or other rights related to the development of, construction
of, ownership or, or use and operation of, the real property (all such items
being collectively referred to as the "INTANGIBLES"), and all furniture,
fixtures and equipment and other items of personal property owned by Seller and
located in or on the real property, as described in Exhibit B attached hereto
and made a part hereof (collectively, the "PERSONALTY") (the Land and
Improvements, together with the Intangibles and Personalty, being hereinafter
sometimes referred to collectively as the "PROPERTY");

      B. Purchaser desires to purchase the Property, and Seller desires to sell
the Property, all pursuant to the following terms.

      NOW, THEREFORE, for and in consideration of the premises and mutual
covenants and agreements herein contained, and for other good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
parties hereto agree as follows:

      1. PURCHASE AND SALE OF THE PROPERTY. Seller agrees to sell and transfer
the Property and its right, title and interest in the Lease (hereinafter
defined), and Purchaser agrees to purchase the Property, together with all of
Seller's right, title and interest in the Lease, pursuant to the terms and
conditions set forth herein.

<PAGE>

      2. PURCHASE PRICE AND METHOD OF PAYMENT.

            2.1 PURCHASE PRICE. The purchase price for which the Seller agrees
to sell and assign the Property (including Seller's interests in the Lease as
aforesaid) and which the Purchaser agrees to pay or deliver to the Seller,
subject to the terms and conditions set forth herein, shall be equal to ELEVEN
MILLION FIVE HUNDRED SEVENTY-FIVE THOUSAND DOLLARS ($11,575,000.00) (the
"PURCHASE PRICE") to be paid as described in Section 2.2 hereof.

            2.2 METHOD OF PAYMENT. The Purchase Price shall be payable by
Purchaser as follows: (i) Purchaser shall, at its option, either assume or
defease the indebtedness outstanding as of the Closing Date (hereinafter
defined) owed by Seller to holder of a certain Promissory Note, dated June 1,
1999, in the original principal amount of $8,800,000.00 made by The Advance
Group/Lake Fairfax, L.L.C. payable to NationsBank, N.A. (the Note")(the current
holder(s) of the Note and its servicers are collectively referred to as the
"EXISTING LENDER"), and secured by the Property and more particularly described
on Exhibit C hereto (the "EXISTING INDEBTEDNESS"); Purchaser shall be
responsible for the assumption fees or, in the event of a defeasance, any
pre-payment penalties and all costs and expenses of such defeasance, and
reasonable costs and expenses of Existing Lender (including reasonable
attorney's fees) related to the assumption or defeasance of the Existing
Indebtedness (the "LOAN FEES") and the amount of the Loan Fees shall not be
deducted from the Purchase Price or be considered to be a part of the Existing
Indebtedness assumed by Purchaser; and (ii) the balance after application of the
assumption or the defeasance amounts described in (i) above, as further adjusted
to account for any reserves held by Existing Lender, in the case of an
assumption, and any prorations and adjustments required hereunder, and minus the
Deposit (below defined) shall be paid by Purchaser in escrow to the Escrow Agent
(below defined) in immediately available U.S. funds.

            2.3 DEPOSIT. Within three (3) business days following the Effective
Date, Purchaser shall deposit with Commercial Title Group, Inc. or another
escrow agent acceptable to Purchaser and Seller (the "ESCROW AGENT") in cash,
One Hundred Fifty Thousand Dollars ($150,000.00) (the "GOOD FAITH DEPOSIT"). The
Good Faith Deposit shall become non-refundable, except as otherwise provided in
this Agreement, in the event the Agreement is not terminated prior to the
expiration of the Inspection Period (below defined). If the Agreement is
terminated prior to the expiration of the Inspection Period, the Good Faith
Deposit will be fully refunded to Purchaser. If Purchaser does not terminate the
Agreement, then within three (3) business days following the expiration of the
Inspection Period, Purchaser will deposit with Escrow Agent the additional sum
of One Hundred Fifty Thousand Dollars ($150,000.00) (the "EARNEST MONEY,"
collectively with the Good Faith Deposit, being hereinafter referred to as the
"DEPOSIT"). The Deposit will be non-refundable except for a default by Seller
under the Agreement, a material casualty, a condemnation, or a failure to meet a
closing condition. As used herein, the term "DEPOSIT" shall include the Deposit
and all interest earned on the Deposit.

            2.4. ESCROW AGENT. The Escrow Agent shall not be liable for any acts
or omissions at any time unless caused by the gross negligence or willful
malfeasance of the Escrow Agent with respect to the escrow established herein.
If a dispute arises between the parties as to the disposition of the Deposit,
the Escrow Agent shall: (a) hold the Deposit until the Escrow Agent has received
releases signed by all parties to the transaction authorizing disposition of the
Deposit, or (b) hold the Deposit until such time as one of the parties to the
transaction files suit and the court in which the suit is filed orders the
disbursement of the

                                       2
<PAGE>

Deposit, or (c) deliver such Deposit into the court by filing an Interpleader
Action. In the event of any litigation between Seller and Purchaser concerning
the Deposit, Escrow Agent's sole responsibility may be satisfied, at Escrow
Agent's option, by delivering the Deposit into the court in which such
litigation is pending, and Purchaser and Seller agree that upon deliverance of
such Deposit into court, neither Purchaser nor Seller shall have any further
right, claim, demand, or action against the Escrow Agent. In the event any
dispute arises under this Agreement between Seller and Purchaser resulting in
the Escrow Agent being made a party to any litigation, Seller and Purchaser,
jointly and severally, shall indemnify the Escrow Agent for all costs, and
reasonable attorneys' fees and legal expenses incurred by the Escrow Agent as a
result thereof, provided that such litigation does not result in a judgment
against the Escrow Agent for acting improperly under this Agreement.
Notwithstanding anything to the contrary contained in this Section 2.4, Escrow
Agent and Seller acknowledge and agree that Purchaser has the unilateral right
to receive a refund of the Deposit pursuant to Section 5.2.

      3. SELLER'S REPRESENTATIONS AND WARRANTIES. In order to induce Purchaser
to enter into this Agreement and to purchase the Property, Seller makes the
following representations and warranties, each of which being true and correct
in all material respects as of the date hereof and, to the extent such
representations and warranties shall still be true and correct in all material
respects on the Closing Date, will reaffirm such on the Closing Date. To the
extent Seller discovers such representations and warranties are no longer true
and correct in all material respects, Seller shall, upon such discovery, provide
prompt written notice to Purchaser, with sufficient detail in order to
reasonably and fully advise Purchaser of any such change. (However, such a
notice shall not effect Purchaser's right to terminate this Agreement under
Section 6.2 hereof.)

            3.1 ORGANIZATION AND AUTHORITY. Seller has full power and authority
to enter into this Agreement, to sell the Property to Purchaser and to otherwise
perform its obligations hereunder. Seller further represents to Purchaser that
the execution, delivery and performance of this Agreement, the fulfillment of
and compliance with the terms and provisions hereof and the due consummation of
the transactions contemplated hereby have been duly and validly authorized and
approved by all requisite organizational action, all of which are in full force
and effect. The purchase and sale of the Property pursuant to this Agreement
(and the consummation of the transactions contemplated herein) shall not violate
any law, ordinance, judgment, decree or order to which Seller or the Property is
subject. Seller is not a "FOREIGN PERSON" as that term is defined by Section
1445 of the Internal Revenue Code of 1986, as amended (the "CODE").

            3.2 NONCONTRAVENTION. Neither the entry into nor the performance of,
or compliance with, this Agreement by Seller has resulted, or will result, in
any violation of, or default under, or result in the acceleration of, any
obligation under any existing organizational documents or agreements, mortgage,
indenture, lien agreement, note, contract, permit, judgment, decree, order,
restrictive covenant, statute, rule, or regulation applicable to Seller.

            3.3 CONSENTS. Each consent, approval, authorization, order, license,
certificate, permit, registration, designation, or filing by or with any
governmental agency or body necessary for the execution, delivery, and
performance of this Agreement or the transactions contemplated hereby by Seller
has been obtained or will be obtained on or before the Closing Date. The tenant
under the Lease, Chubb Computer Services, Inc., has provided Seller with a
written waiver of its rights to purchase the Property, a copy of which waiver is
attached hereto and made a part hereof as Exhibit D.

                                       3
<PAGE>

            3.4 OWNERSHIP. Seller is the sole, fee simple owner of full legal,
equitable and beneficial title to the Property, free and clear of liens and
encumbrances other than the Permitted Exceptions (defined below) and the lien
securing the Existing Indebtedness. To the best of Seller's actual knowledge,
Seller is not in default of any of its obligations under the Permitted
Exceptions, except a potential contingent liability to build an access road as
set forth under that certain letter agreement, dated May 28, 1999, between LFBC
Ten Limited Partnership, Lake Fairfax Seven Limited Partnership and The Advance
Group/Lake Fairfax, LLC.

            3.5. HAZARDOUS WASTES. With respect to the Property (including,
without limitation, the soil and ground water underneath the Improvements), no
summons, citation, directive, notice or complaint issued by the United States
Environmental Protection Agency or other federal or local Government authority
has been received by Seller, its employees or to Seller's knowledge, its agents,
concerning any alleged violations of any environmental laws and regulations or
any investigation or request for information relating to the handling,
packaging, transportation, treatment, storage or disposal of Hazardous
Substances on-site or when transported off-site. To Seller's knowledge, the
Property is in compliance with all laws, regulations, orders, decrees and
agreements relating to Hazardous Substances and there are no Hazardous
Substances on, at or under the Property as of the date hereof. The term
"HAZARDOUS SUBSTANCES" means any "HAZARDOUS CHEMICAL," "HAZARDOUS SUBSTANCE" or
similar term as defined in the Comprehensive Environmental Response,
Compensation and Liability Act of 1980, as amended (42 U.S.C. Section 9601 et
seq.), and all rules and regulations thereunder or in any other applicable
federal, state, or local law, rule or regulation dealing with environmental
protection (including but not limited to petroleum products). For the purposes
of this Agreement, the term Hazardous Substances also includes radon, petroleum
and petroleum products, asbestos and asbestos products, and mold and mildew.

            3.6 CONDEMNATION. No taking by power of eminent domain or
condemnation proceeding or similar proceeding has been instituted or, to
Seller's knowledge, threatened for the permanent or temporary taking or
condemnation of all or any portion of the Property.

            3.7 LITIGATION OR PROCEEDINGS. Seller has not received any notice
and has no knowledge of any action, suit, proceeding or claim affecting the
Property, or any portion thereof, relating to or arising out of the ownership,
operation, use or occupancy of the Property pending, threatened or being
prosecuted in any court or by or before any federal, state, county or municipal
department, commission, board, bureau or agency or other governmental
instrumentality.

            3.8 COMPLIANCE; NOTICE OF VIOLATIONS. Seller has not received any
written notice of any violation of any law, rule, regulation, order,
requirement, code, ordinance, statute or regulation issued by any Government
agency, board, commission, authority or other Government entity, or any
insurance board of underwriters, or of any action in any court or in any
Government or administrative body on account thereof, against or affecting the
zoning, use, development, maintenance, condition or operation of the Property or
any part thereof.

            3.9 LIENS. No labor has been performed or materials furnished at the
request or direction of Seller that could result in a materialman's or
mechanic's lien filed against the Property except as shall be fully paid or
released prior to Closing. All real estate taxes on the

                                       4
<PAGE>

Property which have become due and payable prior to Closing have been or will be
paid by Closing.

            3.10 LEASE. There are no leases, subleases, lease guaranties,
assignments, license agreements or other occupancy agreements for the Property
binding upon the Purchaser or its successors other than the Lease identified on
Exhibit E attached hereto (the "LEASE") and made a part hereof. To the best of
Seller's actual knowledge, the Lease is in full force and effect and shall not
be further extended, modified or amended in any manner prior to Closing without
the Purchaser's consent, which shall not be unreasonably withheld, conditioned
or delayed. To Seller's knowledge, neither landlord nor tenant is in default
under the Lease, and there are no other obligations of the landlord pertaining
to the Property except as expressly set forth in the Lease, Service Contracts,
Loan Documents and other matters disclosed in this Agreement. The tenant under
the Lease has not prepaid rent thereunder except for Property operating
expenses. To the knowledge of Seller, no controversy, claim, dispute or
disagreement exists between the parties to the Lease and no event has occurred
which, with the giving of notice or the passage of time, or both, would
constitute a default under the Lease. To the best of Seller's actual knowledge,
the Lease is valid and enforceable in accordance with its terms and in full
force and effect. Seller has not sent written notice of termination to the
tenant under the Lease. Seller has not received written notice of termination,
default, or challenge to the validity of the Lease from the tenant under the
Lease. There is no security deposit or other deposits or outstanding tenant
improvement obligations under the Lease, except as expressly set forth on
Exhibit E. There are no brokerage, leasing or other commissions payable with
respect to the Lease as of the date hereof, and at Closing, there shall be no
such commissions payable, whether with respect to the present term thereunder or
any renewal term, except as expressly set forth on Exhibit E.

            3.11 SERVICE CONTRACTS. All service, maintenance, supply,
management, leasing contracts or other agreements ("SERVICE CONTRACTS") which
affect the Property are shown on Exhibit F attached hereto and made a part
hereof. To Seller's knowledge, Seller is not in default under any of the Service
Contracts and to its knowledge no other parties to any of the Service Contracts
are in default thereunder. On or before the expiration of the Inspection Period,
Purchaser shall notify Seller which of the Service Contracts, if any, Purchaser
elects to assume at Closing and Purchaser and Seller will enter into a mutually
acceptable assignment and assumption agreement at Closing for all such assumed
Service Contracts. Those Service Contracts not assumed by Purchaser shall be
terminated by Seller on or before Closing, as of the date of Closing. True and
complete copies of the Service Contracts have been or will be delivered to
Purchaser by or on behalf of Seller within five (5) days of the Effective Date
and, to Seller's knowledge, all the Service Contracts are in full force and
effect and none of them has been further modified, amended or extended.

            3.12 NO ACTIONS. Seller shall not take any action or cause or permit
by its agents or employees any action to be taken which would cause any of the
representations or warranties contained or incorporated in this Agreement to be
untrue as of the Closing Date. Seller agrees to notify Purchaser promptly in
writing of any event or condition of which Seller becomes aware which occurs
prior to Closing hereunder and which causes a material change in the truth of
any of the representations or warranties contained herein.

            3.13 EXISTING INDEBTEDNESS. To the extent not previously provided or
made available to Purchaser, Seller represents that copies of the Existing
Indebtedness shall be provided to Purchaser within three (3) business days
following the Effective Date hereof. Seller

                                       5
<PAGE>

represents and warrants to the Purchaser that, to the best of Seller's actual
knowledge, (i) there are no defaults existing, nor has any event occurred which,
with the giving of notice or the passage of time, or both, would constitute a
default, under any loan documents securing or otherwise delivered by Seller in
connection with the Existing Indebtedness; and (ii) the Existing Indebtedness is
assumable subject to the terms of the Existing Indebtedness. As of March 6,
2006, to the best of Seller's actual knowledge, (a) the outstanding principal
amount of the Existing Indebtedness is $7,339,548.04, and (b) the reserves held
by the holder of the Existing Indebtedness are as follows: (i) Replacement
Reserve of $12,588.42 and (ii) Tenant Improvement Reserve of $24,087.15.

            3.14 ABSENCE OF BANKRUPTCY. Neither Seller nor any general partner
of Seller has commenced (within the meaning of any Bankruptcy Law) a voluntary
case, consented to the entry of an order for relief against it in an involuntary
case, or consented to the appointment of a custodian of it or for all or any
substantial part of its property, nor has a court of competent jurisdiction
entered an order or decree under any Bankruptcy Law that is for relief against
Seller or any of its general partners in any involuntary case or appoints a
custodian of Seller or any of its general partners or for all or any substantial
part of its or their property.

            3.15 DRIVEWAYS AND ACCESS. Seller has no actual knowledge of any
federal, state, county, municipal or other governmental plans to change the
highway or road system in the vicinity of the Property or to restrict or change
access from any such highway or road to the Property.

            3.16 UTILITIES. To the best of Seller's actual knowledge, (a) all
water, sewer, gas, electricity, telephone and other utilities required for the
use, occupancy, operation and maintenance of the Improvements are connected
thereto and in service, are adequate to serve the normal operation of the
Property, are supplied directly to the Property by facilities of public or
private utilities, and the cost of installation and connection of such utilities
has been fully paid and (b) all public utilities required for the operation of
the Property enter the Property through lands as to which valid public or
private easements exist that will inure to the benefit of Purchaser.

            3.17 UNDERGROUND STORAGE TANKS. To the best of Seller's actual
knowledge, there are no underground storage tanks located on the Property.
Seller has not removed, or caused to be removed, any underground storage tanks
from the Property and, to the best of Seller's knowledge, no underground storage
tanks were removed from the Property before Seller acquired title to the
Property.

            3.18 PROPERTY INFORMATION. The copies of the Lease, the Guaranty
(hereinafter defined) and the Rent Roll provided or to be provided to Purchaser
are true, accurate and complete in all material respects and, to the best of
Seller's actual knowledge, the copies of the Property Information (hereinafter
defined) delivered or to be delivered by Seller to Purchaser are complete in all
material respects. Except as may otherwise be provided in the Agreement, Seller
does not represent or warrant to Purchaser the truthfulness or accuracy of any
of the Property Information and Purchaser shall rely on such Property
Information at its own risk.

            3.19 LEASE GUARANTY. The Guaranty of Lease dated September 15, 1998
(the "GUARANTY") by Federal Insurance Company (the "GUARANTOR") with regard to
the Lease is in full force and effect, has not been amended, and, to Seller's
knowledge, neither landlord nor Guarantor is in default under the Guaranty.

                                       6
<PAGE>

            3.20 DEED RESTRICTION/PURCHASE OPTION. In connection with the
Special Warranty Deed, Building Restriction, Purchase Option and Grant of
Easements dated June 8, 1999 (the "1999 DEED") with respect to the Land by and
between Lake Fairfax Seven Limited Partnership, as Grantor, and The Advance
Group/Lake Fairfax, LLC, as Grantee, (a) to the best of Seller's actual
knowledge, the tenant under the Lease moved into the Property on or about
January 28, 2000; (b) to the best of Seller's actual knowledge, the Option to
purchase the Service Land and the Service Building (as such terms are defined in
the 1999 Deed) remains in full force and effect, and Seller will assign all of
its rights, title and interest in such Option to Purchaser upon its purchase of
the Property; and (c) Seller has not received an Exercise Notice, as defined in
the 1999 Deed.

            3.21. ZONING. To the best of Seller's actual knowledge, there are no
outstanding zoning proffers applicable to the Property or any part thereof.

      When used in this Section 3 and elsewhere in this Agreement, "TO SELLER'S
KNOWLEDGE," "TO SELLER'S ACTUAL KNOWLEDGE," "SELLER IS NOT AWARE OF," "SELLER
DOES NOT KNOW" and words of similar import mean the knowledge of (i) Shelly R.
Hampton, Seller's Director of Asset Management, and of (ii) Eric L. Smith,
Seller's asset manager, without investigation or duty of investigation, and such
words expressly do not include any constructive or imputed knowledge.

      Seller shall have the right, from time to time after the Effective Date
and at or prior to Closing, to amend its representations and warranties set
forth above due to any change in the facts outside the control of and otherwise
not caused by Seller and not actually known by Seller as of the Effective Date
by providing Purchaser with written notice thereof and providing the specific
nature of such untrue representation; provided, however, in the event that
Seller does so amend its representations or warranties (in any material adverse
respect with respect to representations and warranties not qualified by
materiality), Purchaser shall have the right, as its sole remedy for such
amendment, to terminate this Agreement, and receive a refund of the Deposit, if
Seller does not cure or otherwise correct such matter to the Purchaser's
reasonable satisfaction. Seller's representations and warranties shall survive
Closing for a period of twelve (12) months thereafter and same shall constitute
a contingent liability of Seller during such survival period. Notwithstanding
the foregoing, no representation or warranty shall be deemed to have survived
Closing, if Purchaser shall have had actual knowledge of a breach or violation
of such representation or warranty at the time of Closing and elected to proceed
to Closing notwithstanding such breach or violation.

      4. PURCHASER'S REPRESENTATIONS AND WARRANTIES. In order to induce Seller
to enter into this Agreement and to sell the Property, Purchaser makes the
following representations and warranties, each of which being true and correct
in all material respects as of the date hereof and each of which shall be true
and correct in all material respects on the Closing Date.

            4.1 ORGANIZATION AND AUTHORITY. Purchaser has full power and
authority to enter into this Agreement. Purchaser will have at Closing, full
power and authority to purchase the Property from Seller and to otherwise
perform its obligations hereunder. Purchaser further represents to Seller that
the execution, delivery and performance of this Agreement, the fulfillment of
and compliance with the terms and provisions hereof and the due consummation of
the transactions contemplated hereby will be at Closing duly and validly
authorized and approved by all requisite organizational action, all of which
will be in full force and effect. The purchase of the Property pursuant to this
Agreement (and the consummation of the transactions

                                       7
<PAGE>

contemplated herein) will not violate any law, ordinance, judgment, decree or
order to which Purchaser is subject.

            4.2 NONCONTRAVENTION. Neither the entry into nor the performance of,
or compliance with, this Agreement by Purchaser has resulted, or will result, in
any violation of, or default under, or result in the acceleration of, any
obligation under any existing organizational documents or agreements, mortgage,
indenture, lien agreement, note, contract, permit, judgment, decree, order,
restrictive covenant, statute, rule, or regulation applicable to Purchaser.

            4.3 LITIGATION OR PROCEEDINGS. Purchaser has received no notice and
has no knowledge of any action, suit, proceeding or claim affecting Purchaser
pending, threatened or being prosecuted in any court or by or before any
federal, estate, county or municipal department, commission, board, bureau or
agency or other governmental instrumentality that impairs or affects Purchaser's
ability to enter into this Agreement and perform its obligations hereunder or
that could materially and adversely affect the business, financial position, or
results of operations of the Purchaser.

            4.4 CONSENTS. Except as may otherwise be set forth in Section 6
hereof, each consent, approval, authorization, order, license, certificate,
permit, registration, designation, or filing by or with any governmental agency
or body necessary for the execution, delivery, and performance of this Agreement
or the transactions contemplated hereby by the Purchaser has been obtained or
will be obtained on or before the Closing Date.

      5. INSPECTION; CONDITION OF PROPERTY AND TITLE.

            5.1 RIGHT OF INSPECTION. Purchaser shall have the right, at its own
risk, cost and expense, at any time prior to Closing during normal business
hours (i.e. Monday through Friday from 9:00 a.m. to 5:00 p.m. (federal holidays
excepted) upon not less than twenty-four (24)) hours prior notice to Seller, and
subject to the approval of the tenant under the Lease with respect to any entry
into the leased premises (if required under the terms of the Lease), to enter,
or cause its agents or representatives to enter, upon the Property for the
purpose of making surveys, tests, test borings, inspections, investigations and
architectural, structural, economic, environmental and other studies of the
Property as Purchaser may deem desirable and to interview the tenant under the
Lease. Seller shall, within two (2) business days after the Effective Date
(unless otherwise provided on Exhibit M), forward to Purchaser all of the
documents related to the Property as set forth on Exhibit M attached hereto and
made a part hereof (the "PROPERTY INFORMATION") to the extent such Property
Information is in the possession of Seller or within Seller's reasonable
control. Seller agrees that it shall reasonably cooperate with Purchaser in
connection with any other information regarding the Property reasonably
requested by Purchaser and will provide or make available such information
during the Inspection Period and at all periods thereafter through the Closing
to the extent in Seller's possession. Purchaser shall, at Purchaser's sole cost
and expense, promptly and fully restore any damage or destruction to the
Property occurring as a result of any act or omission of Purchaser by reason of
such tests, studies or investigations. Purchaser shall indemnify, defend and
hold Seller harmless from and against all loss, cost, damage or claim (including
attorneys' fees reasonably incurred, court costs and costs of investigation)
arising out of or resulting from Purchaser's exercise of the right and privilege
granted to Purchaser contained in this Section 5.1, and the undertakings
contained in this Section 5 shall survive Closing or prior termination of this
Agreement. The parties acknowledge that Purchaser may be required to perform a
historical

                                       8
<PAGE>

audit of the Property in order to comply with Item 3-14 of Regulation S-X
promulgated under the Securities Act of 1933 and the Securities Exchange Act of
1934. Seller shall, effective as of the Closing Date, made commercially
reasonable efforts to permit Purchaser's auditors access at that location where
Seller customarily maintains its records, upon reasonable advance notice and
during normal business hours, to all of the Property's books and records and the
operating statements (certified by an officer of the general partner of Seller)
and property management balance sheets for the Property for one (1) calendar
year prior to the Closing Date and for the period from the end of the prior
fiscal year through the Closing Date. To the extent that the originals or copies
of same are not otherwise provided by Seller to Purchaser at the Closing, and to
the extent that the same are ordinarily maintained by Seller in its normal
course of business, such books and records shall include the detail general
ledger of profits and loss, accounts receivable records, rent rolls, billing
records, accounts payable records, and contracts. Purchaser's access rights
shall commence on the Closing Date and shall continue until the successful
completion of the audit and the filing of the 3-14 report with the SEC, written
notice of which shall be delivered promptly by Purchaser to Seller. The
foregoing obligation shall fully survive the Closing. Notwithstanding anything
to the contrary in the foregoing, other than providing the access to Purchaser
specified herein, Seller shall not have any liability or responsibility in
connection with or in any manner related to, directly or indirectly, any audit
required to be made by Purchaser or any compliance required of Purchaser with
any Regulation under the Securities Act of 1933 or the Securities Act of 1934.

            5.2 INSPECTION PERIOD. Purchaser's obligations under this Agreement
are subject to Purchaser's approval of the Property for Purchaser's intended use
and to satisfaction of certain other contingencies more fully described below.
Purchaser shall have the period commencing on the Effective Date and ending at 5
p.m. on that date which is thirty (30) days after the Effective Date (the
"INSPECTION PERIOD") to inspect the Property and to conduct such tests and
investigations as it deems advisable in order to determine that the Property can
be used for Purchaser's intended use. If, during the Inspection Period,
Purchaser in its sole discretion is not satisfied with its findings hereof for
any or no reason whatsoever, Purchaser shall notify Seller and Escrow Agent in
writing (prior to the expiration of the Inspection Period) in which event:

                  a. the Good Faith Deposit shall be returned to Purchaser by
Escrow Agent without any authorization by Seller;

                  b. this Agreement shall be terminated; and

                  c. the parties shall be relieved of any further obligation and
responsibility under this Agreement, subject only to the Purchaser's obligations
under Section 5.1.

It is expressly recognized and agreed by the parties that if Purchaser fails to
terminate this Agreement prior to the expiration of the Inspection Period,
Purchaser shall be deemed to have waived its termination right under this
Section 5.2, and the entire Deposit shall thereupon be deemed at risk to
Purchaser, subject to the other terms of this Agreement. Consequently, should
Purchaser wrongfully fail to settle on the Property pursuant to the terms of
this Agreement, the Deposit shall be non-refundable to Purchaser and paid to
Seller in accordance with the Default provisions below as final, liquidated
damages.

                                       9
<PAGE>

            5.3 "AS-IS AND WHERE IS CONDITION". The Purchaser acknowledges that,
except as otherwise expressly set forth herein and subject to Purchaser's rights
in Sections 5.1 and 5.2 above, it is accepting the Property "as is and where
is," in its present physical condition, which Purchaser is familiar with or has
had adequate opportunity to become familiar with. Except as specifically
provided in this Agreement, the Purchaser acknowledges that Seller has made no
representations or warranties to the Purchaser regarding the condition of the
Property.

            5.4 TITLE EXAMINATION. Purchaser shall have until the expiration of
the Inspection Period, at Purchaser's sole expense, to obtain title and survey
examinations of the Property and owner's title insurance commitments, in form
and substance, and issued by a title insurance company, acceptable to Purchaser
and subject only to those exceptions to title to the Property Purchaser agrees
to accept. If Purchaser is not satisfied with the state of title or survey
matters to the Property, Purchaser shall notify Seller of such title or survey
objections in writing ("OBJECTIONS NOTICE") prior to the expiration of the
Inspection Period. If Seller does not agree in writing ("SELLER'S RESPONSE")
within five (5) days of Seller's receipt of the Objection Notice to attempt to
cure any such title or survey objections raised by Purchaser (which Seller shall
not be obligated to do), then Purchaser may terminate this Agreement by
providing written notice thereof to Seller within five (5) days of Purchaser's
receipt of the Seller's Response or if no such written notice is received by
Purchaser within five (5) days of the date Seller's Response was due, in which
event the Deposit shall be returned to Purchaser and neither party shall have
any further rights or obligations hereunder, except as expressly provided
herein. If (i) Purchaser fails to deliver an Objections Notice, or (ii) Seller
does not agree in writing to attempt to cure any such noticed title or survey
objections and Purchaser fails to terminate this Agreement pursuant hereto,
then, in either event, Purchaser shall be deemed to have waived any such title
or survey objections and shall proceed to Closing without any reduction in the
Purchase Price, in which event the Property will be conveyed to Purchaser
subject to such title or survey objections and such title or survey objections
shall thereafter constitute "PERMITTED EXCEPTIONS" for all purposes of this
Agreement. If Seller undertakes in writing to attempt to cure any noticed title
or survey objections raised by Purchaser, but Seller is unable to cure such
title or survey objections at or prior to Closing, then, subject to Section 6.2,
Purchaser may terminate this Agreement by providing written notice thereof to
Seller, in which event the Deposit shall be returned to Purchaser and neither
party shall have any further rights or obligations hereunder.

            5.5 ASSUMPTION OF EXISTING INDEBTEDNESS. Commencing on the Effective
Date, Purchaser shall work actively and in good faith with Existing Lender to
ensure that Purchaser will be able to timely and satisfactorily assume the
Existing Indebtedness at Closing. Seller shall cooperate with Purchaser in good
faith prior to Closing in connection with such Purchaser efforts, and shall sign
such documents as may be reasonably required by Existing Lender to effectuate
such assumption. In connection therewith and as a condition to Seller's
obligations hereunder, Seller and any guarantors shall be released from any
obligations under the Existing Indebtedness which accrue after the Closing.
Purchaser shall be responsible for the Loan Fees and such amounts shall not be
deducted from the Purchase Price.

      6. CONDITIONS PRECEDENT TO CLOSING.

            6.1 PURCHASER'S CONDITIONS PRECEDENT TO CLOSING. It shall be a
condition precedent to Purchaser's obligation to make a full settlement
hereunder that each and every one of the following conditions shall exist on the
Closing Date:

                                       10
<PAGE>

                  a. REPRESENTATIONS AND WARRANTIES. Each of Seller's
representations and warranties contained herein shall be true and correct in all
material respects in the same manner and with the same effect as though such
representations and warranties had been made on and as of the Closing Date. In
addition, Seller shall have complied with its obligations under Sections 8 and
13 below as of the Closing Date.

                  b. CONDITION OF PROPERTY. Seller shall not have committed
waste or nuisance upon the Property and shall have maintained and kept the
Property (including the grounds thereof) in substantially the same order and
condition as exists as of the date hereof, normal wear, tear and obsolescence
excepted. Seller shall not cause any renovations, alterations or significant
cosmetic changes to be made at or to the Property prior to Closing except
required repairs and any alterations or changes made with Purchaser's written
consent (which consent shall not be unreasonably delayed, withheld or
conditioned). Seller shall not have undertaken or permitted any action within
Seller's control, without the consent of Purchaser, which would impair or
otherwise affect the use, ownership, acquisition or development of the Property
on or after Closing in any material, adverse respect or which would cause any of
the representations or warranties set forth herein to be untrue in any material
respect.

                  c. EXISTING INDEBTEDNESS. The Existing Indebtedness shall have
been assumed or defeased by Purchaser, and all necessary consents related to the
Existing Indebtedness (including, but not limited to the delivery of all
assumption or defeasance documents executed by Existing Lender) shall have been
received by Purchaser. Purchaser shall be responsible for any Loan Fees,
including, but not limited to, pre-payment penalties and other expenses
associated with defeasance of the Existing Indebtedness. In the event that
Purchaser elects to exercise its option to cause a defeasance of the Existing
Indebtedness, Seller shall cooperate fully with Purchaser to effectuate such
defeasance, including without limitation, by executing documents requested by
the holder of the Existing Indebtedness required to effectuate the defeasance.

                  d. TENANT ESTOPPEL CERTIFICATE. Seller shall obtain from the
tenant of the Lease and shall deliver to Purchaser at least three (3) business
days prior to Closing, a signed estoppel certificate, dated no more than thirty
(30) days prior to the Closing Date, in the form of the estoppel certificate
attached hereto and made a part hereof as Exhibit G or in the form which may be
required by the Lease. If Seller has obtained the foregoing estoppel certificate
in accordance with this subparagraph and Purchaser exercises its right pursuant
to Section 7 to extend the date of Closing, Seller shall make reasonable efforts
to update or obtain a new estoppel certificate, but such updated or new estoppel
certificate shall not be a condition to Purchaser's obligations under this
Agreement.

                  e. CC&R ESTOPPEL CERTIFICATES. Purchaser shall obtain from
each Benefited Owner (as such term is defined in the Ingress-Egress Easement and
Maintenance Agreement dated February 26, 1999 and recorded among the land
records of Fairfax County, Virginia at Deed Book 10896, Page 1139), at least
three (3) business days prior to Closing, a signed estoppel certificate, dated
no more than thirty (30) days prior to the Closing Date, in the form of the
estoppel certificate attached hereto and made a part hereof as Exhibit H-1.
Purchaser shall obtain from Lake Fairfax Business Center Owners' Association at
least three (3) business days prior to Closing, a signed estoppel certificate,
dated no more than thirty (30) days prior to the Closing Date, in the form of
the estoppel certificate attached hereto and made a part hereof as Exhibit H-2.
If Purchaser has obtained either of the foregoing estoppel certificates in
accordance

                                       11
<PAGE>
with this subparagraph and Purchaser exercises its right pursuant to Section 7
to extend the date of Closing, while Purchaser may attempt to update or obtain a
new estoppel certificate, the receipt of such update or new estoppel certificate
shall not be a condition to Purchaser's obligations under this Agreement. Seller
agrees to cooperate with Purchaser in the obtaining of the certificates required
by this paragraph. If Purchaser shall fail to obtain the foregoing certificates
prior to the Closing, Seller may extend the Closing for up to twenty (20) days
by giving Purchaser written notice of such extension prior to the originally
scheduled Closing in order to provide Seller with an opportunity to obtain such
certificates.

                  f. GUARANTOR ESTOPPEL CERTIFICATE. Seller shall obtain from
Guarantor and shall deliver to Purchaser at least three (3) business days prior
to Closing, a signed estoppel certificate, dated no more than thirty (30) days
prior to the Closing Date, in the form of the estoppel certificate attached
hereto and made a part hereof as Exhibit I or in the form which may be required
by the Guaranty. If Seller has obtained the foregoing estoppel certificate in
accordance with this subparagraph and Purchaser exercises its right pursuant to
Section 7 to extend the date of Closing, Seller shall make reasonable efforts to
update or obtain a new estoppel certificate, but such updated or new estoppel
certificate shall not be a condition to Purchaser's obligations under this
Agreement.

            6.2 FAILURE OF CONDITION TO PURCHASER'S OBLIGATIONS. In the event of
the failure of any condition precedent set forth in Section 6.1 above as of the
Closing Date, Seller shall have the right to extend the Closing Date by written
notice to Purchaser prior to the Closing Date by up to ten (10) days, in order
to attempt to satisfy such condition. In the event of the failure as of the
Closing Date (as the same may have been extended) of any condition precedent set
forth in Section 6.1 above, Purchaser, at its sole election, may, at its option,
either:

                  a. terminate this Agreement, in which event the Deposit shall
be returned to Purchaser and, if the failure of a condition precedent is under
Section 6.1 a or 6.1 b and such failure is caused by the Seller, Seller shall
reimburse Purchaser for all out-of-pocket costs actually incurred by Purchaser
in connection with the negotiation of this Agreement and the reasonable pursuit
by Purchaser of the transactions contemplated hereunder, including without
limitation, reasonable attorney's fees and all consultant's costs to investigate
the Property (collectively, the "PURSUIT COSTS") up to a maximum amount of Forty
Thousand Dollars ($40,000.00), whereupon neither party shall have any further
obligations or liabilities to the other, subject only to the obligations of the
Purchaser under Section 5.1, or

                  b. waive the condition and proceed to Closing.

     However, nothing contained herein shall be deemed to affect the rights of
Purchaser under Section 6.1 in the event Seller has breached a representation or
warranty made by Seller under this Agreement, or Seller shall default in its
obligations to settle on the Property. Notwithstanding the foregoing, the
failure of Seller to obtain any of the estoppel certificates described in
subsections d, e or f of Section 6.1 shall not be an event of default under this
Agreement.

      7. CLOSING. Prior to the end of the Inspection Period, Purchaser shall
advise Seller in writing if Purchaser elects to assume the Existing Indebtedness
or to defease the Existing Indebtedness. The purchase and sale contemplated
herein shall be consummated at a settlement ("CLOSING") which shall take place
on the date (the "CLOSING DATE") that is (i) forty-five (45) days after the
expiration of the Inspection Period, if Purchaser has elected to defease the
Existing

                                       12
<PAGE>

Indebtedness, or (ii) ten (10) business days after the Existing Lender has
approved Purchaser's assumption of the Existing Indebtedness. The Existing
Lender shall not be deemed to have approved Purchaser's assumption of the
Existing Indebtedness until the Existing Lender and Purchaser have agreed upon
the final form of all assumption documents. If Purchaser has elected to assume
the Existing Indebtedness and in the event that Existing Lender has not approved
Purchaser's assumption by the date which is forty-five (45) days after the
expiration of the Inspection Period, Purchaser shall have the right to terminate
this Agreement, upon written notice to Seller, and to receive a return of the
Deposit. If such assumption has not been approved within sixty (60) days after
the expiration of the Inspection Period, Seller shall have the right to
terminate this Agreement, upon written notice to Purchaser, and Purchaser shall
receive a return of the Deposit. The Closing shall take place during normal
business hours on the Closing Date at the offices of the Escrow Agent or at such
other location as the parties may mutually agree. Purchaser shall have the right
to extend the Closing Date by an additional thirty (30) days by posting an
additional Two Hundred Fifty Thousand Dollars ($250,000.00) as part of the
non-refundable Deposit with the Escrow Agent, upon three (3) days written notice
prior to the original Closing Date.

      8. SELLER'S DELIVERIES. Seller, with respect to the Property, shall
execute, as appropriate, and deliver to the Escrow Agent at Closing:

            8.1 DEED. Special warranty deed ("DEED") in the form attached hereto
and made a part hereof as Exhibit J, whereunder Seller grants and conveys fee
simple title to the Property.

            8.2 ASSIGNMENT OF LEASE AND SERVICE CONTRACTS. An agreement (the
"ASSIGNMENT AND ASSUMPTION AGREEMENT") evidencing the Seller's assignment and
the Purchaser's assumption of the Lease and any accepted Service Contracts as of
the Closing Date in the form attached hereto and made a part hereof as Exhibit
K.

            8.3 SELLER'S AFFIDAVITS. Such certificates, owner's affidavits and
other evidence signed and delivered by Seller, as may reasonably be required to
induce the title company to issue the Title Policy, without exception except for
the Permitted Exceptions and the liens securing the Existing Indebtedness.

            8.4 FIRPTA AFFIDAVIT. An affidavit certifying that Seller is not a
"FOREIGN PERSON" as that term is defined by Section 1445 of the Code.

            8.5 RESOLUTIONS. Seller's resolutions authorizing the sale
contemplated herein and the execution of this Agreement and all other documents
delivered by Seller at Closing and such other certificates, documents and
instruments as may reasonably be required by the title company to issue the
Title Policy.

            8.6 BILL OF SALE. A bill of sale in the form attached hereto and
made a part hereof as Exhibit L, conveying to Purchaser all Personal Property
and the Intangibles, and all of Seller's right, title and interest, to the
extent assignable, in and to any (i) unexpired warranties and guarantees now in
effect with respect to any part of the Property and/or mechanical equipment and
appliances at the Property, (ii) all architectural, engineering, rezoning and
subdivision plans (if any), specifications, drawings, and reports, and (iii) all
licenses and permits relating to the Property to the extent the same exist and
are assignable.

                                       13
<PAGE>

            8.7 POSSESSION; KEYS. Possession of the Property and keys for the
Improvements in the possession or control of Seller or its agents.

            8.8 ORIGINAL DOCUMENTS. The originals (or copies if originals are
not available) of all the Building Documents.

            8.9 FILES. To the extent available, originals (or copies, if
originals are not available) of all documents and books and records necessary
for the continued operation of the Property, other than proprietary information,
including without limitation, Lease files, rent records, escalation records and
statements and maintenance records.

            8.10 NOTICE OF SALE. Sufficient original letters, executed by
Seller, advising the tenant under the Lease of the sale of the Property to
Purchaser and directing that all rents and other payments thereafter becoming
due be sent to Purchaser or as Purchaser may direct.

            8.11 TERMINATION OF MANAGEMENT AGREEMENT. A termination of
management agreement executed by Seller and its managing agent(s) terminating
any management agreement(s) relating to the Property.

            8.12 TERMINATION OF LEASING AGREEMENT. A termination of leasing
commission agreement executed by Seller and its leasing agent(s) terminating any
leasing agreement(s) relating to the Property, which termination shall set forth
any amounts which Purchaser may be required to pay (with respect to extensions
and renewals) after the Closing, but only to the extent such amounts are
specifically set forth on Exhibit E.

            8.13 GENERAL LEDGERS. Detail general ledgers and trial balances for
the Property, in Excel format, for the fiscal year prior to the Closing Date and
for the interim period from the most recent fiscal year through the Closing
Date.

            8.14 OTHER DOCUMENTS. Any other documents reasonably required by
Purchaser's title company, including but not limited to a Virginia Department of
Taxation Form R-5E and all necessary information for IRS Form 1099-S.

      9. PURCHASER'S CLOSING OBLIGATIONS. Purchaser shall assume or defease the
Existing Indebtedness, and shall pay all other funds required hereunder to be
paid by the Purchaser in connection with the Closing, by federal wire transfer
to the Escrow Agent on the Closing Date. Purchaser shall also execute the
Assignment and Assumption Agreement, and such other documents or instruments as
the Escrow Agent or title company may reasonably require in connection with the
Closing.

      10. SETTLEMENT CHARGES; PRORATIONS AND ADJUSTMENTS.

            10.1 ALLOCATION OF SETTLEMENT CHARGES. Seller shall pay the
Grantor's Tax and the cost of preparation of the Deed in connection with the
Property. Purchaser shall pay the recordation taxes on the Deed, title
examination fees, the title insurance premium, any survey costs, all costs
involved with the assumption of the Existing Indebtedness, including but not
limited to, all assumption fees and costs of Existing Lender's legal fees, all
clerk's and indexing fees and all other settlement expenses except as otherwise
expressly set forth in this Section 10.1. Purchaser and Seller each shall pay
their own legal fees related to the preparation of this Agreement and all
documents required to settle the transaction contemplated hereby.

            10.2 PRORATIONS AND ADJUSTMENTS. At Closing, interest on the
Existing Indebtedness, rents (to the extent prepaid), all real and personal
property taxes, water rents,

                                       14
<PAGE>

sewer charges, electric and other utility charges, operating expenses, any
special assessments, if any, owner's association assessments, and other similar
charges affecting the Property shall be adjusted and prorated as of midnight of
the day prior to the Closing Date, the day of Closing being a day of income and
expense for the Purchaser. Seller shall assign to Purchaser at Closing all of
Seller's right, title and interest in and to reserves, if any, held by the
holder of the Existing Indebtedness as of the Closing Date. Such amount of
reserves will be credited to Seller and paid by Purchaser on the Closing Date.
To the extent practicable, Seller shall attempt to have utility providers read
the meters for the Property on the day prior to Closing for purposes of making
such prorations and adjustments. All other charges or fees customarily prorated
and adjusted in similar transactions shall be adjusted at Closing. All rent
(other than prepaid rent, which shall be paid by Seller to Purchaser) payable by
the tenant of the Property shall be adjusted (prorated) as of the Closing Date
and paid in accordance with the following provisions:

                  a. Base Rent (as defined in the Lease) and Additional Rent (as
defined in the Lease) under the Lease attributable to the month in which the
Closing occurs, shall be adjusted as of the Closing, with Seller being entitled
to the portion thereof attributable to the period of the month immediately
preceding the Closing Date and Purchaser entitled to the balance of such monthly
installment.

                  b. Purchaser shall be entitled to all Base Rent and other sums
due under the Lease to the extent collected on any date after the Closing with
the exception of (a) common area maintenance ("CAM") and real estate tax
reimbursements attributable to periods prior to the Closing; (b) the Base Rent
for the Closing month to which Seller is entitled under (i) above, and (c) to
the extent specified in Subsection c. below, rentals paid by the tenant on
account of rental arrearages for periods preceding the Closing. Annual CAM and
tax reimbursements which are payable by the tenant on an annual basis for the
year of Closing after the conclusion of the calendar year, will be adjusted with
the tenant within ninety (90) days after the expiration of such calendar year
and shall be apportioned between Seller and Purchaser as of the date of Closing,
with Seller being entitled to the portion thereof attributable to the period of
the year immediately preceding the Closing Date and Purchaser being entitled to
the balance of such payment. Purchaser shall pay over to Seller within two (2)
business days following receipt the portion of the installment to which the
Seller is entitled. Additionally, any post-Closing tenant payments of amounts
for special services which were specifically billed by Seller prior to the
Closing Date shall be remitted by Purchaser to Seller within two (2) business
days following Purchaser's receipt thereof.

                  c. Base Rent and Additional Rent which are due, but
uncollected, as of the Closing shall not be adjusted, but Purchaser shall cause
the rent for the period prior to Closing to be remitted to Seller if, as and
when collected, less any reasonable, out-of-pocket expenses incurred by
Purchaser for such collection; provided, that, except with respect to Base Rent
and Additional Rent for the Closing month, which shall be treated as specified
in (i) above, all rents collected subsequent to Closing by Purchaser shall first
be applied to current rentals then due which have accrued subsequent to Closing
and any remaining amounts shall be applied to rental arrearages as of Closing.
Similarly, if Seller receives any Base Rent or other sums under the Lease which
are payable to Purchaser under this Section 10.2, then Seller shall promptly
deliver such sums to Purchaser. Purchaser, at Seller's request, will use
reasonable efforts for six (6) months after the Closing Date to collect past due
rental amounts or other payments owed to

                                       15
<PAGE>

Seller in accordance with this Section 10.2, except that Purchaser has no
obligation to incur any out-of-pocket expenses in the course of such collection
efforts.

                  d. Seller agrees to pay in full as of the Closing Date the
following amounts with respect to the Lease as of the Effective Date: (i) all
leasing commissions and brokerage fees owing in connection with the current
terms of such Lease, (ii) the tenant improvement allowance (if any) due and
payable under such Lease, (iii) the cost of completing any commenced tenant
improvements (if any) even if completion is to occur after Closing, and (iv) to
the extent applicable, any relocation, rent subsidies or other expenses or
incentives offered to the tenant under such Lease in order to satisfy or
terminate the obligations of the tenant to a landlord under another lease.
Purchaser shall be responsible for any commissions, tenant improvements or other
such expenses accruing in connection with leases entered into by Purchaser after
Closing.

All adjustment items to the extent they cannot be precisely determined at
Closing (or to the extent found to be erroneous after the Closing), shall be
estimated at Closing and shall be resolved by the parties in good faith no later
than sixty (60) days after the Closing.

            10.3 RELEASE OF CLOSING ESCROW. Upon receipt of Purchaser's
deliveries required under Section 9 above, and subject to all of Seller's
deliveries having been received and such other conditions to Purchaser's
performance as are contained in Section 6.1 hereof, Escrow Agent shall record
the Deed, disburse the settlement proceeds as indicated on the settlement
statement signed by Purchaser and Seller, and distribute all Closing documents
as directed by counsel for Purchaser and Seller.

      11. CONDEMNATION AND RISK OF LOSS. The risk of condemnation of all or any
portion of the Property or loss or damage to the Property by fire or other
casualty shall be borne by the Seller until Closing. In the event of (a) the
threatened or actual commencement of eminent domain proceedings or actual
condemnation or taking of all or any part of the Property, or (b) damage to the
Property by fire or other casualty, act of God or any other event on or prior to
the Closing Date, which would cost in excess of Four Hundred Thousand Dollars
($400,000.00) to repair or cause a material loss in the income generated by such
Property, Purchaser, at its sole option exercisable within thirty (30) days
following receipt of written notice of the event giving rise to the exercise of
such option, shall have the right to terminate this Agreement, in which event
the Deposit shall be returned to Purchaser, and neither party shall have any
further obligations or liabilities to the other, subject to the obligations of
the Purchaser under Section 5 above. In the event of a casualty which does not
fall within (b) above, then the Closing shall occur as provided herein.
Purchaser understands and agrees that if it does not exercise its termination
option in the event of condemnation or casualty as described in (a) or (b)
above, or if Purchaser is required to proceed to Closing pursuant to the
immediately preceding sentence, the terms and conditions of the documents
governing the Existing Indebtedness will control the use of any insurance
proceeds and the settlement of any insurance claims related thereto with respect
to the Property, and that Purchaser will have no rights with respect to such
proceeds or claims. Notwithstanding the foregoing, in such an event, Seller
shall assign all of its rights to applicable insurance or condemnation proceeds,
as applicable, to Purchaser and the Purchase Price shall be reduced by the
amount of any deductible under such insurance policy. The provisions of this
Section 11 shall expressly survive Closing and delivery of the Deed for the
Property.

      12. DEFAULT PROVISIONS; REMEDIES.

                                       16
<PAGE>

            12.1 PURCHASER'S DEFAULT. If Purchaser fails to consummate the
purchase contemplated herein after all conditions precedent to Purchaser's
obligation to consummate the transactions herein contemplated have been
satisfied or waived by Purchaser, and Seller is not in default hereunder, and
Seller has notified Purchaser of such default and Purchaser has failed to cure
such default within ten (10) days of Seller's written notice, then Escrow Agent
shall deliver to Seller the Deposit. In such event, the Deposit shall be deemed
as full and complete liquidated damages and the sole and exclusive remedy of
Seller, the parties hereby agreeing that they have considered carefully the loss
to Seller that would be a consequence of such default and that the Deposit is a
reasonable estimate of such loss. Upon payment to Seller of the Deposit, this
Agreement shall terminate, and neither party shall have any further obligations
or liabilities to any other party, other than any obligations or liabilities
which expressly survive any termination of this Agreement.

            12.2 SELLER'S DEFAULT. Except as otherwise provided herein, if
Seller breaches its representations, warranties, covenants and/or agreements
hereunder or fails to consummate the sale contemplated herein by the Closing
Date after all conditions precedent to Seller's obligations hereunder have been
satisfied or waived by Purchaser and provided that Purchaser is not in default
hereunder, and Purchaser has notified Seller of such default and Seller has
failed to cure such default within ten (10) days of Purchaser's written notice
then, except as otherwise provided herein, Purchaser shall be entitled, at its
option, to notify Seller of the election by Purchaser to terminate this
Agreement, whereupon Escrow Agent shall return the Deposit to Purchaser, Seller
shall reimburse Purchaser for its Pursuit Costs in connection with the
transactions contemplated by this Agreement (including but not limited to
reasonable attorneys' and consultants' fees) up to a maximum aggregate amount
equal to Forty Thousand Dollars ($40,000.00), such costs to be included in
Purchaser's written notice accompanied by reasonable documentation evidencing
such Pursuit Costs, and neither party will have any further obligation to the
other hereunder, other than the obligations of the Purchaser under Section 5.
Alternatively, in the event the Seller shall fail to close as required
hereunder, Purchaser, at its election, shall be entitled to bring suit for
specific performance, inasmuch as the parties recognize and acknowledge that the
Property owned by Seller is unique, and that there is no adequate remedy at law
to compensate fully Purchaser for a breach by Seller of Seller's obligations to
convey the Property of the Seller to Purchaser in accordance with the terms and
conditions of this Agreement. Except as otherwise specifically provided for
under this Section 12.2, in no event shall Purchaser be entitled to monetary
damages for a default by Seller to close hereunder.

      13. OBLIGATIONS OF SELLER PENDING CLOSING. Between the date hereof and the
Closing Date, Seller agrees:

            13.1 OCCUPANCY AT CLOSING. The parties understand that the Property
will be delivered subject only to the rights of the tenant under the Lease and
rights of parties under the Service Contracts assumed by Purchaser, Permitted
Exceptions and the Existing Indebtedness.

            13.2 LEASING. Seller agrees that it will not enter into any new
leases for premises in the Property or extend, modify or terminate the existing
Lease without the Purchaser's consent, which consent shall not be unreasonably
delayed, withheld or conditioned (except that Purchaser shall have no obligation
to consent to any termination of the Lease under any circumstance).

                                       17
<PAGE>

            13.3 MAINTENANCE AND OPERATION OF PROPERTY. Seller shall continue to
maintain the Property consistent with its prior practices, in order that its
present operating condition be maintained, normal wear and tear excepted, and
shall cause the continuation of the normal operation thereof, including the
purchase and replacement of supplies and equipment. Seller shall not remove or
permit to be removed from the Property any Personalty, except as may be
necessary for repairs or discarding worn out or useless items, provided that
discarded items shall be replaced with new items of substantially equal quality
and quantity and shall be free and clear of any lien or encumbrance.

            13.4 NO ACTION. Seller shall not knowingly take any action or
direct, require or advise any other person or entity to take any action that
would invalidate, void or make untrue any representation or warranty provided
under this Agreement or otherwise breach this Agreement.

            13.5 ADDITIONAL DELIVERIES. Seller shall deliver to Purchaser
promptly following its receipt copies of any notices received by Seller or its
management agent from the holder of any liens existing against the Property or
the tenants pertaining to the Property from and after the date hereof through
Closing.

            13.6 SCHEDULED PAYMENTS OF THE EXISTING INDEBTEDNESS. Seller will
make the scheduled monthly payments of principal and interest under the Existing
Indebtedness until Closing and shall not take any action or fail to take any
action which would constitute a default under the Existing Indebtedness.

      14. MISCELLANEOUS PROVISIONS.

            14.1 COMPLETENESS AND MODIFICATION. This Agreement constitutes the
entire agreement between the parties hereto with respect to the transactions
contemplated herein, and it supersedes all prior discussions, understandings or
agreements between the parties. This Agreement shall not be modified or amended
except by an instrument or writing signed by and on behalf of the parties.

            14.2 ADDITIONAL DOCUMENTS. Purchaser and Seller agree that they
will, within six (6) months after the Closing, duly execute and deliver to each
other any additional conveyances, assignments, documents and instruments, and
shall take or cause to be taken such further actions (including the making of
filings), which are necessary in connection with the consummation of the
acquisition and contribution contemplated herein.

            14.3 SEVERABILITY. If fulfillment of any provision of this
Agreement, or performance of any transaction related hereto, at the time such
fulfillment or performance shall be due, shall involve transcending the limit of
validity prescribed by law, then the obligation to be fulfilled or performed
shall be reduced to the limit of such validity; and if any clause or provision
contained in this Agreement operates or would prospectively operate to
invalidate this Agreement in whole or in part, then such clause or provision
only shall be held ineffective, as though not herein contained, and the
remainder of this Agreement shall remain operative and in full force and effect.

            14.4 CUMULATIVE REMEDIES. Except as specifically provided in this
Agreement, each and every of the rights, benefits, and remedies provided to
Purchaser or Seller by this Agreement, or any instruments or documents executed
pursuant to this Agreement, are

                                       18
<PAGE>

cumulative and shall not be exclusive of any other rights, remedies and benefits
allowed to such party by this Agreement, at law or in equity.

            14.5 CONSTRUCTION. Each party hereto hereby acknowledges that all
parties hereto participated equally in the negotiation and drafting of this
Agreement and that, accordingly, no court construing this Agreement shall
construe it more stringently against one party than against the other.

            14.6 PRONOUNS. All pronouns and any variations thereof shall be
deemed to refer to the masculine, feminine, neuter, singular or plural, as the
identity of the person or entity may require.

            14.7 BINDING EFFECT; ASSIGNMENT. This Agreement shall be binding
upon and inure to the benefit of the parties hereto, and their respective
successors and permitted assigns. Purchaser may not assign this Agreement
without the prior written consent of Seller, which consent shall not be
unreasonably withheld, conditioned or delayed; provided, however, that Purchaser
shall have the right to assign this Agreement (or any portion hereof) to one or
more subsidiaries or affiliates of Purchaser without Seller's consent, so long
as Purchaser has direct or indirect control or management of any such assignee.
Seller shall not assign this Agreement.

            14.8 WAIVER; MODIFICATION. Failure by Purchaser or Seller to insist
upon or enforce any of its rights hereto shall not constitute a waiver thereof.

            14.9 GOVERNING LAW. This Agreement shall be governed by and
construed under the laws of the Commonwealth of Virginia.

            14.10 HEADINGS. The headings are used herein for convenience of
reference only, and shall not be deemed to vary the content of this Agreement.

            14.11 EXHIBITS. All Exhibits attached hereto are incorporated herein
and made a part of this Agreement.

            14.12 COUNTERPARTS. To facilitate execution, this Agreement may be
executed in as many counterparts as may be required; and it shall not be
necessary that the signature of each party, or that the signatures of all
persons required to bind any party, appear on each counterpart; but it shall be
sufficient that the signature of each party or that the signatures of the
persons required to bind any party, appear on one or more such counterparts. All
counterparts shall collectively constitute a single agreement. This document and
any amendment hereto may be executed by facsimile and any such facsimile shall
be deemed to constitute an original for all purposes hereof.

            14.13 NOTICES. All notices, requests, consents, and other
communications hereunder shall be in writing and shall be personally delivered,
sent by facsimile transmission, sent by Federal Express or other recognized
overnight delivery service, prepaid by the party sending such notice, to the
addresses indicated below.

            IF INTENDED FOR SELLER TO:
                  Armada/Hoffler Investment Properties, L.P.
                  222 Central Park Avenue
                  Suite 2100
                  Virginia Beach, Virginia 23462
                  Fax No.: (757) 424-2513

                                       19
<PAGE>

                  Attention: Shelly R. Hampton

            WITH A COPY TO:
                  Faggert & Frieden, P.C.
                  222 Central Park Avenue, Suite 1300
                  Virginia Beach, Virginia 23462
                  Fax No.:  (757) 424-0102
                  Attention: David Y. Faggert

            IF INTENDED FOR PURCHASER TO:
                  Columbia Equity Trust, Inc.
                  1750 H Street, NW, Suite 500
                  Washington, D.C. 20006
                  Fax No.:  (202) 303-3088
                  Attention:  Clinton D. Fisch

            WITH A COPY TO:
                  Watt, Tieder, Hoffar & Fitzgerald LLP
                  8405 Greensboro Drive, Suite 100
                  McLean, Virginia 22102
                  Fax No. (703) 749-0479
                  Attention: Colin J. Smith, Esq.

      The addresses and parties set forth above may be changed from time to time
by any party by notice to the other. For purposes of this Agreement, notices
shall be effective upon receipt or refusal thereof.

            14.14 SECTION 1031 EXCHANGE. Upon request of either party made not
later than five (5) business days prior to Closing, Purchaser and Seller agree
to reasonably cooperate with the other (at the requesting party's sole cost and
expense) in structuring the purchase and sale of the Property as contemplated by
this Agreement as part of a like-kind exchange pursuant to Section 1031 of the
Code. The requesting party shall indemnify the other party against all costs
associated with the like-kind exchange process. The like-kind exchange shall not
reduce, diminish or adversely affect the parties' rights or remedies under this
Agreement in any respect, nor shall the consummation of the exchange cause any
delay in the Closing.

            14.15 BUSINESS DAY. As used herein, the term "BUSINESS DAY" shall
mean any day other than a Saturday or Sunday, or other day recognized as a
holiday by the U.S. Government.

            14.16 SURVIVAL. It is the express intention and agreement of the
parties hereto that the covenants, agreements, statements, representations,
warranties and indemnities made in this Agreement by the respective parties
shall survive the execution and delivery of the Deed at Closing for twelve (12)
months following Closing.

            14.17 ATTORNEYS' FEES. If any party institutes any proceeding or
action to obtain enforce this Agreement against another party, the party which
substantially prevails in such proceeding or action, as determined by the
trier-of-fact, shall be entitled to be reimbursed by the non-prevailing party
for reasonable, out-of-pocket costs and other expenses, including reasonable

                                       20
<PAGE>

attorneys' fees, incurred by the substantially prevailing party in connection
with such proceeding or action.

            14.18 WAIVER OF JURY. SELLER AND PURCHASER EACH HEREBY IRREVOCABLY
WAIVES TRIAL BY JURY IN ANY ACTION OR PROCEEDING BROUGHT BY OR AGAINST THE OTHER
PARTY UNDER OR IN CONNECTION WITH THIS AGREEMENT.

            14.19 BROKERAGE COMMISSION. Seller and Purchaser represent and
warrant to each other that they have dealt with no brokers or finders in
connection with the sale of the Property other than Cushman and Wakefield (the
"BROKER") and that no brokerage fee or real estate commission is or shall be due
or owing in connection with this transaction other than to the Broker, who shall
be paid solely by Seller in accordance with the terms of a separate written
agreement. Seller and Purchaser hereby indemnify and hold the other harmless
from any and all loss, costs or damage (including, without limitation,
reasonable attorneys fees and expenses) arising out of any claims of any broker
or agent so claiming based on action or alleged action of the indemnifying party
recognizing the Seller alone shall bear the cost of the Broker as aforesaid.
This Section 14.19 shall survive Closing.

            14.20 CONFIDENTIALITY. All surveys, tests, studies, inspections and
investigations conducted by Purchaser under this Agreement, all documents, books
and records provided by Seller to Purchaser under this Agreement, including
without limitation the Building Documents and the Lease, and all terms of this
Agreement will be treated by Purchaser as confidential information, and
Purchaser will not disclose the same to any other person other than its
attorneys, accountants, prospective lenders, mortgage bankers, financial
advisors or investors, and any architects, engineers or consultants specifically
retained by Purchaser in connection with its acquisition of the Property. It is
understood by Seller that Purchaser may be required to disclose certain details
of this transaction in order to comply with Securities and Exchange Commission
guidelines which may be applicable to Purchaser as a public real estate
investment trust. Purchaser will advise all such attorneys, accountants,
prospective lenders, mortgage bankers, financial advisors and investors,
architects, engineers and consultants of the confidential nature of such
information, and will instruct each such person to maintain confidentiality. All
documents, books and records provided by Purchaser to Seller under this
Agreement and all terms of this Agreement will be treated by Seller as
confidential information, and Seller will not disclose the same to any person
other than its attorneys. Both parties' obligations under this Section 14.20
will survive any termination of this Agreement.

            14.21 STANDSTILL PERIOD. Until Closing or the earlier termination of
this Agreement by either party, Seller agrees that it will not, directly or
indirectly, offer to sell, or solicit any offers to purchase or negotiate for
the sale or disposal of the Property with any other party other than Purchaser.

            14.22 EFFECTIVE DATE. THE "EFFECTIVE DATE" SHALL BE THE DATE
UPON WHICH BOTH SELLER AND PURCHASER HAVE EXECUTED THIS AGREEMENT AND AN
ORIGINAL THEREOF HAS BEEN DELIVERED TO EACH.

[THE BALANCE OF THIS PAGE HAS BEEN LEFT BLANK INTENTIONALLY]

                                       21
<PAGE>

IN WITNESS WHEREOF, the parties hereto have executed this Agreement under seal
as of the day and year first above written.

                              PURCHASER:

                              COLUMBIA EQUITY TRUST, INC., a Maryland
                              corporation

                              By: /s/ Clinton Fisch
                                  ----------------------------------------------
                              Name: Clinton Fisch
                              Title: SVP

                              SELLER:

                              ARMADA/HOFFLER INVESTMENT PROPERTIES, L.P.

                              By: AGLF, INC., its General Partner

                              By: /s/ Louis S. Haddad
                                  ----------------------------------------------
                                  Louis S. Haddad, Vice President

                              ESCROW AGENT:

                              COMMERCIAL TITLE GROUP, INC.

                              By: /s/ Douglas Nichols
                                  ----------------------------------------------
                              Name: Douglas Nichols
                              Title: President

                                LIST OF EXHIBITS

<TABLE>
<S>                 <C>
EXHIBIT A           Legal Description - Property
EXHIBIT B           Schedule of Personal Property
EXHIBIT C           Description of Existing Indebtedness
EXHIBIT D           Chubb Waiver Letter
EXHIBIT E           Schedule of Lease, Security Deposits, Commissions, Tenant
                    Improvements
EXHIBIT F           Schedule of Service Contracts
EXHIBIT G           Form of Tenant Estoppel Certificate
EXHIBIT H-1         Form of CC&R Estoppel Certificate (Ingress-Egress Easement)
EXHIBIT H-2         Form of CC&R Estoppel Certificate (Declaration)
EXHIBIT I           Form of Guarantor Estoppel Certificate
EXHIBIT J           Form of Deed
EXHIBIT K           Form of Assignment and Assumption of Lease and Contracts
EXHIBIT L           Form of Bill of Sale
EXHIBIT M           Property Information
</TABLE>


                                       22
<PAGE>

                                    EXHIBIT A
                          LEGAL DESCRIPTION - PROPERTY

ALL THOSE CERTAIN lots, pieces or parcels of land, situate, lying and being in
Fairfax County, Virginia, and more particularly described as follows:

All of that certain lot, piece or parcel of land known as Parcel 10A-1, Lake
Fairfax Business Center, as shown on that certain plat entitled "PLAT SHOWING
MINOR LOT LINE ADJUSTMENT OF PARCELS 9 AND 10A LAKE FAIRFAX BUSINESS CENTER
HUNTER MILL DISTRICT FAIRFAX COUNTY, VIRGINIA", dated January 29, 1999, which
plat is attached to instrument recorded in Deed Book 10916 at Page 469, among
the land records of Fairfax County, Virginia, and being more particularly
described by metes and bounds as follows:

Beginning at an iron pipe found on the southeasterly line of Parcel 7A, Lake
Fairfax Business Center marking the northwesterly corner of Parcel 8, Lake
Fairfax Business Center; thence with the westerly line of said Parcel 8, Lake
Fairfax Business Center

S 12 degrees 44' 54" E, 106.60 feet

To an iron pipe set marking the most northerly corner of Parcel 9A, Lake Fairfax
Business Center;

Thence with the northwesterly line of said Parcel 9A, Lake Fairfax Business
Center;

S 47 degrees 02' 27" W, 320.90 feet

To an iron pipe set on the northeasterly line of Outlot D, Reston, Section 909
marking the most westerly corner of Parcel 9A, Lake Fairfax Business Center;

Thence with said northeasterly line of Outlot D, Reston, Section 909 and
continuing with the northeasterly lines of Outlot E and Outlot F, Reston,
Section 909

N 42 degrees 58' 28" W, 580.18 feet

To an iron pipe set on the southeasterly corner of Outlot 8A, Reston, Section
909 and marking the northeasterly corner of said Outlot F, Reston, Section 909;

Thence with the northeasterly line of said Outlot 8A, Reston, Section 909

N 42 degrees 57' 01" W, 134.16 feet

To an iron pipe set marking the most southerly corner of Parcel 18B, Lake
Fairfax Business Center;

Thence with the southeasterly lines of Parcel 18B, Lake Fairfax Business Center;

N 47 degrees 02' 59" E, 182.60 feet to an iron pipe set and

N 41 degrees 05' 46" E, 179.37 feet

To an iron pipe set on the southwesterly line of aforementioned Parcel 7A, Lake
Fairfax Business Center marking the southeasterly corner of said Parcel 18B,
Lake Fairfax Business Center;

Thence with the southwesterly and southeasterly lines of said Parcel 7A, Lake
Fairfax Business Center the following eight (8) courses:

S 31 degrees 54' 10" E, 549.42 feet to an iron pipe set;

<PAGE>

S 58 degrees 05' 50" W, 75.01 feet to an iron pipe set;

S 31 degrees 54' 10" E, 36.00 feet to an iron pipe set;

S 42 degrees 05' 39" E, 45.21 feet to an iron pipe set;

S 31 degrees 54' 10" E, 50.00 feet to an iron pipe set;

N 58 degrees 05' 50" E, 85.51 feet to an iron pipe set;

N 31 degrees 54'10" W, 56.83 feet to an iron pipe set and

N 59 degrees 38' 08" E, 117.84 feet to the point of beginning.

Containing 209,973 square feet or 4.82032 acres of land, more or less.

TOGETHER WITH AND SUBJECT TO the rights, benefits, burdens and obligations
created by that certain Ingress-Egress Easement and Maintenance Agreement dated
February 26, 1999 and recorded on April 30, 1999 in Deed Book 10896 at Page
1139, among the Land Records of Fairfax County, Virginia.

AND BEING the same property conveyed to Armada/Hoffler Investment Properties,
L.P., a Virginia limited partnership by Deed from The Advance Group/Lake
Fairfax, LLC, a Virginia limited liability company dated as of November 17, 2000
and recorded December 12, 2000 among the land records of Fairfax County,
Virginia in Deed Book 11632 at page 1125.


                               EXHIBIT A, PAGE 2
<PAGE>

                                    EXHIBIT B
                          SCHEDULE OF PERSONAL PROPERTY

                                      NONE

<PAGE>

                                    EXHIBIT C
                      DESCRIPTION OF EXISTING INDEBTEDNESS

1.    PROMISSORY NOTE

2.    DEED OF TRUST, ASSIGNMENT OF LEASES AND RENTS AND SECURITY AGREEMENT
      RECORDED IN BOOK 10955, PAGE 1545 IN THE CLERK'S OFFICE

3.    LOAN AGREEMENT

4.    ENVIRONMENTAL INDEMNIFICATION AGREEMENT

5.    UCC-1 FINANCING STATEMENT FILED WITH THE CLERK'S OFFICE AS FILE NO.
      99-6308

6.    UCC-1 FINANCING STATEMENT FILED WITH THE CHESAPEAK CLERK'S OFFICE AS FILE
      NO. 62847

7.    UCC-1 FINANCING STATEMENT FILED WITH THE SCC AS FILE NO. 9906117002

8.    ASSIGNMENT OF DEED OF TRUST, DATED SEPTEMBER 20, 2000 RECORDED IN DEED
      BOOK 11633, AT PAGE 380 IN THE CLERK'S OFFICE F FAIRFAX COUNTY (THE
      "FAIRFAX CLERK'S OFFICE")

9.    CONSENT AND ASSUMPTION AGREEMENT WITH RELEASE RECORDED IN DEED BOOK 11633,
      AT PAGE 385 IN THE CLERK'S OFFICE

10.   ENVIRONMENTAL AND HAZARDOUS SUBSTANCE INDEMNITY AGREEMENT

11.   UCC 1 FINANCING STATEMENT, BEING FILE NO. 00-013046, IN THE CLERK'S OFFICE

12.   UCC AMENDMENT TO FINANCING STATEMENT, BEING FILE NO. 00-013047, IN THE
      CLERK'S OFFICE

13.   UCC AMENDED FINANCING STATEMENT RECORDED AS INSTRUMENT NO. 062847 IN THE
      CLERK'S OFFICE, CITY OF CHESAPEAKE

14.   UCC FINANCING STATEMENT RECORDED AS INSTRUMENT NO. 065763 IN THE CITY OF
      CHESAPEAKE, CLERK'S OFFICE

<PAGE>

15.   UCC FINANCING STATEMENT FILED WITH THE SCC AS INSTRUMENT NO. 00-12-13-7007

16.   UCC FINANCING STATEMENT AMENDMENT FILED WITH THE SCC AS INSTRUMENT NO.
      01-01-08-7016


                               EXHIBIT A, PAGE 2
<PAGE>

                                    EXHIBIT E
     SCHEDULE OF LEASES, SECURITY DEPOSITS, COMMISSIONS, TENANT IMPROVEMENTS

                  1. Schedule of Leases.

Deed of Lease, dated effective as of September 15, 1998, between The Advance
Group/Lake Fairfax, L.L.C. (the "Original Landlord") and Chubb Computer
Services, Inc. ("Tenant"), as modified by an Agreement, dated April 28, 1999,
between Original Landlord, Tenant and Armada/Hoffler Construction Company, and
as amended pursuant to a First Amendment to Lease Agreement, dated effective as
of May 4, 1999, and a Second Amendment to Lease Agreement, dated February 7,
2000, and a Guaranty of Lease, made as of September 15, 1998, made by Federal
Insurance Company in favor of the Original Landlord.

2.    Security Deposit. - None

3.    Commissions - None

4.    Tenant Improvements - None