<PAGE>
                                                                  Exhibit 10.24


                    ASSIGNMENT OF CONTRACTS AND AGREEMENTS

                                 DEFINED TERMS

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EXECUTION DATE: As of November 25, 1998
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LOAN: A first deed of trust loan in an amount of $21,500,000.00 from Assignee
      to Assignor
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ASSIGNOR & ADDRESS:          Arlington Square Limited Partnership,
                             a Virginia limited partnership
                             c/o The Washington Corporation
                             4650 East-West Highway, Suite 251
                             Bethesda, Maryland 20814
                             Attention: William N. Demas
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ASSIGNEE & ADDRESS:          Metropolitan Life Insurance Company,
                             a New York corporation
                             200 Park Avenue, 12th Floor
                             New York, New York 10166
                             Attention: Senior Vice-President
                                        Real Estate Investments

          and:               Metropolitan Life Insurance Company
                             One Madison Avenue
                             New York, New York 10010-3690
                             Attention:  Vice-President and Investment Counsel
                                         Real Estate Investments
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NOTE: Promissory Note executed by Assignor in favor of Assignee in the amount of
the Loan dated as of the Execution Date, together with all extensions, renewals,
modifications, restatements and amendments thereof.
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DEED OF TRUST: Deed of Trust, Security Agreement and Fixture Filing dated as of
the Execution Date, executed by Assignor to secure repayment of the Note,
together with all extensions, renewals, modifications, restatements and
amendments thereof. The Deed of Trust will be recorded in the records of the
County in which the Property (defined below) is located.
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         THIS ASSIGNMENT OF CONTRACTS AND AGREEMENTS (this "ASSIGNMENT") is
entered into by Assignor as of the Execution Date in favor of Assignee and
affects Agreements (as defined below). Capital terms which are not defined in
this Assignment shall have the respective meanings set forth in the Deed of
Trust.

                                    RECITALS

         A. Assignee has loaned or will loan to Assignor the Loan evidenced
by the Note. Payment of the Note is secured by the Deed of Trust which
encumbers Assignor's interest in the real property more particularly
described in EXHIBIT A attached to Deed of Trust and certain other property
more particularly described in the Deed of Trust and referred to in this
Assignment as the "PROPERTY".

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          B. Assignor desires to absolutely, presently and unconditionally
assign to Assignee all of its right, title and interest in and to the
Agreement (defined below) in the manner hereinafter provided.

          NOW, THEREFORE, in consideration of the Recitals and for good and
valuable consideration, Assignor agrees with Assignee and its successors and
assigns as follows:

          1. PAYMENT OF NOTE. Assignor desires to secure (a) the timely payment
of the principal and interest on the Note and all other indebtedness secured
by the Deed of Trust and (b) the full compliance with the terms, conditions,
covenants and agreements contained in the Note, the Deed of Trust and the other
documents executed by Assignor in connection with the Loan.

          2. PRESENT AND ABSOLUTE ASSIGNMENT OF CONTRACTS. Assignor absolutely,
presently and unconditionally grants, assigns and transfers to Assignee all
right, title and interest which Assignor may now or hereafter have under:

                (a) each of the contracts, agreements, purchase orders, work
          orders, commitments, licenses, guarantees, warranties, permits and
          like or similar agreements identified on EXHIBIT A attached hereto,
          as the same may be amended, modified, supplemented, extended, renewed,
          substituted or replaced from time to time (the "EXISTING AGREEMENTS");
          and

                (b) all contracts, agreements purchase orders, work orders,
          commitments, licenses, guarantees, warranties, permits and like or
          similar agreements in which Assignor may hereafter obtain an interest,
          relating to the use, maintenance, operation, occupancy, management,
          design, construction, development, furnishing, outfitting or equipping
          of the Property, as the same may be amended, modified supplemented,
          extended, renewed, substituted or replaced from time to time (the
          "FUTURE AGREEMENTS"; collectively with the Existing Agreements, the
          "AGREEMENTS").

This assignment is made as part of the consideration for the transactions
contemplated by the Deed of Trust and the other Loan Documents, it being
intended by Assignor and Assignee that such assignment constitutes an
absolute assignment and not an assignment for additional security only. The
foregoing assignment encompasses the right of Assignor to terminate any of
the Agreements, to perform thereunder and to compel performance and otherwise
exercise all remedies thereunder, together with the immediate and continuing
right to collect and receive all sums that may become due to Assignor or that
Assignor may now or shall hereafter become entitled to demand or claim,
arising from or out of the Agreements, including claims of Assignor for
refunds or damages arising out of, or for breach of, or default under, any of
the Agreements and all rights of Assignor to receive proceeds of any
insurance, indemnity, warranty or guaranty with respect to any of the
Agreements.

          3. NO CANCELLATION OR MODIFICATION OF THE AGREEMENTS. Assignor
covenants and agrees that, without the prior written consent of Assignee and
except as otherwise permitted in the Deed of Trust, Assignor will not:

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                (a) further sell, pledge, assign, mortgage or otherwise
          encumber or transfer (except hereby) the Agreements or any right,
          title or interest of Assignor therein;

                (b) except as otherwise permitted under the Deed of Trust,
          waive, excuse, condone, discount, set off, compromise, or in any
          manner release or discharge any party to any of the Agreements of and
          from any obligations, covenants, terms, conditions and agreements to
          be kept, observed and performed by such party; and

                 (c) except as otherwise permitted under the Deed of Trust,
          amend, modify, extend, terminate or cancel, or permit the amendment,
          modification, extension, termination or cancellation, of any of the
          Agreements in any material respect or waive any rights of Assignor
          thereunder.

If any of these acts described in this SECTION 3 are done without the consent
of Assignee or as otherwise permitted under the Deed of Trust, at the option
of Assignee, they shall be of no force or effect and shall constitute a
breach of the terms of this Agreement and of the Deed of Trust.

         4. SPECIFIC COVENANTS OF ASSIGNOR. Assignor covenants and agrees:

                  (a) to keep, observe, perform, comply with and discharge,
         or cause to be kept, observed, performed, complied with and discharged,
         in a timely manner all the material terms and provisions of the
         Agreements to be kept, observed, performed, complied with and
         discharged by Assignor;

                  (b) to give promptly to Assignee copies of all notices of
         default that Assignor shall send or receive under the Agreements;

                  (c) if Assignor fails to make any payment or to do any acts
         required by this Assignment, then Assignee may in its sole discretion
         and without notice to Assignor perform Assignor's obligations under the
         Agreements as Assignee may deem necessary, at Assignor's cost and
         expense. These acts may include without limitation appearing in and
         defending any proceeding connected with the Agreements, including
         without limitation any proceedings of any parties thereto under the
         Bankruptcy Code. No action by Assignee shall release Assignor from its
         obligations under this Agreement. Assignor irrevocably appoints
         Assignee its true and lawful attorney to exercise its rights under this
         Assignment, which appointment is coupled with an interest and with full
         power of substitution;

                  (d) to pay immediately upon demand all sums expended by
         Assignee under this Assignment, together with interest at the Default
         Rate (as defined in the Note). These expenditures shall be secured by
         the Deed of Trust:

                  (e) if a petition under the Bankruptcy Code shall be filed
         by or against Assignor and Assignor, as debtor thereunder, shall
         determine to reject any Agreement pursuant to Bankruptcy Code
         Section 365(a), then Assignee shall have the right, but not the
         obligation, to demand that Assignor assume and assign such Agreement
         to Assignee;

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<PAGE>

                  (f) except as otherwise permitted under the Deed of Trust,
         to enforce and obtain, short of termination thereof, the performance
         of each and every material obligation, term, covenant, condition and
         agreement in the Agreements to be kept, observed, performed, complied
         with and discharged in relation to the other parties to such Agreements
         (each such other party, a "CONTRACTOR", and collectively, the
         "CONTRACTORS"), and exercise such rights and remedies under each
         Agreement and take such other action as may be necessary or proper to
         protect the interests of Assignor and Assignee thereunder, unless
         expressly released and discharged from such obligation by Assignee in
         writing;

                  (g) to appear in and defend (with counsel reasonably
         satisfactory to Assignee) any action or proceeding arising under or in
         any manner connected with the Agreements or Assignor's duties or
         liabilities thereunder and upon request by Assignee (as an additional
         party), to do so in the name and on behalf of Assignee but at the
         expense of Assignor, and to pay all reasonable costs and expenses of
         Assignee, including reasonable attorney's fees, forum costs and
         disbursements, incurred with respect to any such action or proceeding;

                  (h) to deliver to Assignee at its request executed and
         certified copies of the Agreements and all amendments or modifications
         thereof;

                  (i) to obtain, within thirty (30) days after the date
         hereof, a written consent to this Assignment, containing an agreement,
         in form and substance reasonably satisfactory to Assignee, from the
         Contractor under each Existing Agreement in excess of $25,000.00 that,
         upon the exercise by Assignee of its rights hereunder, such Contractor
         shall continue to perform under this respective Agreement for the
         benefit of Assignee, unless, with respect to such Agreement, Assignee
         waives such requirement;

                  (j) to include in each Future Agreement in excess of
         $25,000, a provision, in form and substance reasonably satisfactory to
         Assignee, pursuant to which the Contractor thereunder consents to this
         Assignment and agrees that, upon the exercise by Assignee of its rights
         hereunder, such Contractor shall continue to perform under its
         respective Agreement for the benefit of Assignee, unless, with respect
         to such Agreement, Assignee waives such requirement; provided that
         Assignee hereby agrees that, with respect to Future Agreements
         consisting of work orders for government tenants, Assignor shall obtain
         the Contractor's consent and agreement described above, but such
         consent and agreement may be contained in a separate document executed
         by the Contractor and need not be included in the work order; and

                  (k) that Assignee's rights under this Assignment may be
         exercised either independently of or concurrently with any other right
         in this Assignment, the Deed of Trust, any other Loan Document, the
         Guaranty or the Unsecured Indemnity Agreement. No action taken by
         Assignee under this Assignment shall cure or waive any default nor
         affect any notice under the Deed of Trust.

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          5.  REPRESENTATIONS AND WARRANTIES.  Assignor represents and
          warrants that:

                  (a)  Assignor has the right, power and authority to sell,
          assign, transfer, set over and deliver all of its right, title and
          interest in and to the Existing Agreements;

                  (b)  Assignor has duly and timely performed to date all
          of the obligations, terms, covenants, conditions and warranties of
          the Existing Agreements to be kept, observed and performed by
          Assignor and has not done any act which might prevent Assignee from
          exercising its rights under this Assignment;

                  (c)  except as set forth on EXHIBIT A, the Contractors
          have duly and timely performed to date all of the obligations,
          terms, covenants, conditions and warranties of the Existing
          Agreements to be kept, observed and performed by each such
          Contractor;

                  (d)  Assignor has not previously sold, assigned,
          mortgaged, pledged or otherwise transferred or encumbered any of
          the Agreements, or any right, title or interest therein and, except
          as set forth on EXHIBIT A, none of the Existing Agreements has
          expired or been terminated;

                  (e)  the Existing Agreements are in full force and
          effect on the date hereof, subject to no defenses, setoffs, claims
          or counterclaims whatsoever and have not been amended or modified
          in any material respect except as set forth on EXHIBIT A;

                  (f)  the Existing Agreements identified on EXHIBIT A
          constitute all contracts, agreements, purchase orders, work orders,
          commitments, licenses, guarantees, warranties, permits and like or
          similar agreements in which Assignor has an interest relating to
          the use, maintenance, operation, occupancy, management, design,
          construction, development, furnishing, outfitting or equipping of the
          Property, other than leases or occupancy agreements with space
          tenants; and

                  (g)  Assignor and the undersigned representatives of
          Assignor represent that it and they have full power, authority and
          legal right to execute this Assignment and to observe and perform
          all of the terms of this Assignment on Assignor's part to be
          observed and performed and that this Assignment and the other Loan
          Documents constitute valid and binding obligations of Assignor,
          enforceable in accordance with their respective terms, except as
          such enforcement may be limited by bankruptcy laws and other laws
          affecting the rights of creditors generally, or by virtue of the
          application of general principals of equity.

          6.  ASSIGNOR'S LICENSE UNTIL DEFAULT BY ASSIGNOR.  So long as no
Event of Default exists and so long as there is no default by Assignor under
this Assignment or under any of the Agreements (all of the foregoing are
collectively referred to as a "DEFAULT"), Assignor shall have a license to
obtain, use and enjoy the benefits of the Agreements, including the right to
collect and retain all sums that may become payable to Assignor under the
Agreements. This license shall be terminated at the sole option of Assignee,
without regard to the adequacy of its security

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<PAGE>

under this Assignment or under the Deed of Trust and without notice to
Assignor, if there is a Default.

          7.  REVOCATION OF LICENSE. Upon the occurrence of a Default,
whether or not legal proceedings have commenced, and without regard to
waste, adequacy of security for the Secured Indebtedness or solvency of
Assignor, the license herein granted shall automatically expire and
terminate, without notice by Assignee (any such notice being hereby expressly
waived by Assignor). Assignee shall thereupon and thereafter have all right,
power and authority to exercise and enforce any and all of its rights and
remedies as provided herein, under any of the other Loan Documents or by law
or in equity. Such rights and remedies shall expressly include the right to
exercise and enjoy, in Assignee's sole and absolute discretion, all of the
rights, powers and benefits under the Agreements assigned to Assignee
hereunder, it being understood and agreed that Assignee shall not be liable,
and Assignor shall at all times remain solely liable, to the other parties to
such Agreements to perform any and all duties or obligations owing to such
parties under the Agreements, unless Assignee shall elect, in its sole and
absolute discretion, to undertake such duties or obligations.

          8.  INDEMNIFICATION. Assignor shall indemnify Assignee against and
hold it harmless from any and all liability, claims, loss or damage which it
may incur and which arises out of or relates to any of the Agreements or this
Assignment.

          9.  SATISFACTION AND TERMINATION. Upon the payment in full of the
Loan, as evidenced by the recording of an instrument of full satisfaction of
the Deed of Trust, this Assignment shall be void and of no effect.

          10.  NO OBLIGATION. Nothing in this Assignment shall (a) be
construed to obligate Assignee (i) to appear in or defend any action or
proceeding relating to the Agreements or the Property, or (ii) to take any
action or incur any expense or perform or discharge any obligation, duty or
liability under the Agreements, (b) operate to place any obligation or
liability for the control, care, management or repair of the Property upon
Assignee or (c) operate to make Assignee responsible or liable for any waste
committed on the Property by the Contractors or any other person or entity,
or for any dangerous or defective condition of the Property, including the
presence of any Hazardous Materials or for any negligence in the management,
upkeep, repair or control of the Property resulting in loss or injury or
death to any Contractor, tenant, licensee, employee or any other person or
entity. Although Assignee has the right to do so, it shall not be obligated
to perform any obligation under any Agreement by reason of this Assignment.
To the fullest extent permitted by law, neither this Assignment nor any
action or inaction on the part of Assignee shall constitute an assumption on
the part of Assignee of any obligation or liability under any of the
Agreements.

          11.  CONTRACTORS ENTITLED TO RELY ON ASSIGNEE'S REQUESTS. Assignor
irrevocably authorizes and directs the Contractors and their successors upon
receipt of any written request of Assignee stating that a Default exists, to
make any and all payments due and to become due under such Agreements to
Assignee. Assignor agrees that the Contractors shall have the right to rely
upon any such statement without any obligation to inquire as to whether a
Default actually exists and regardless of any claim of Assignor to the
contrary. Assignor agrees that it shall have

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<PAGE>

no claim against the Contractors for any payments made by the Contractors to
Assignee. Upon the curing of all Defaults, Assignee shall give written notice
to the Contractors to recommence making payments to Assignor.

          12. SUCCESSORS AND ASSIGNS. This Assignment shall be binding upon
the successors and assigns of Assignor and shall inure to the benefit of and
be enforceable by Assignee, its successors and assigns and any trustee
appointed for the benefit of the holder of the Note. If more than one person,
corporation, partnership or other entity shall execute this Assignment, then
the obligations of the parties executing the Assignment shall be joint and
several.

          13. EXCULPATION. The provisions of Section 9.01 of the Deed of
Trust are incorporated herein by this reference to the fullest extent as if
the text of such section were set forth in its entirety herein.

          14. NOTICES. All notices pursuant to this Assignment shall be given
in accordance with the Notice provision of the Deed of Trust, which is
incorporated into this Assignment by this reference.

          15. GOVERNING LAW. This Assignment and the rights and obligations
of the parties under this Assignment shall in all respects be governed by,
and construed and enforced in accordance with, the laws of the State in which
the Property is located, without regard to conflict of laws principles.

          16. MISCELLANEOUS. This Assignment may be modified, amended,
waived, or terminated only by an instrument in writing signed by the party
against which enforcement of such modification, amendment, waiver, or
termination is sought. No failure or delay in exercising any of these rights
shall constitute a waiver of any Default. Assignor, at its expense, will
execute all documents and take all action that Assignee from time to time may
reasonably request to preserve and protect the rights provided under this
Assignment. The headings in this Assignment are for convenience of reference
only and shall not expand, limit or otherwise affect the meanings of the
provisions. This Assignment may be executed in several counterparts, each of
which shall be an original, but all of which shall constitute one document.

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





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     IN WITNESS WHEREOF, Assignor has, by its duly authorized
representatives, duly executed this Assignment under seal as of the day and
year first above written.

          ASSIGNOR:          ARLINGTON SQUARE LIMITED PARTNERSHIP,
                             a Virginia limited partnership

                             By:  Arlington Square, Inc.,
                                  a Virginia corporation,
                                  its general partner


                                  By:  /s/ William N. Demas     [SEAL]
                                       -------------------------------
                                       William N. Demas
                                       President






                                      8


<PAGE>




STATE OF District of                          )
                                              )ss:
CITY/COUNTY OF: Columbia                      )

On the 24th day of November in the year 1998 before me, the undersigned, a
notary public in and for said state, personally appeared William N. Demas,
President of Arlington Square, Inc., the general partner of Arlington Square
Limited Partnership, who is personally known to me or proved to me on the
basis of satisfactory evidence to be the individual whose name is subscribed
to the within instrument and acknowledged to me that he executed the same on
behalf of and in his capacity as President of said corporation, the general
partner of said partnership.


                                             /s/ Veronica Jenkins
                                             ----------------------------

My Commission Expires:

         VERONICA JENKINS
NOTARY PUBLIC, DISTRICT OF COLUMBIA
My Commission Expires April 30, 2003



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<PAGE>

                                     EXHIBIT A

                               THE EXISTING AGREEMENTS


1.  Service Contracts - see list attached hereto as Exhibit A-1.

2.  Management Agreement dated January 1, 1998 by and between Greenway Asset
    Management, L.C. and Arlington Square Limited Partnership, for the
    management of the property located at 4401 North Fairfax Drive,
    Arlington, Virginia.

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                                   EXHIBIT A-1

                                 ARLINGTON SQUARE
                                 SERVICE PROVIDERS

<TABLE>
<CAPTION>

Vendor                      Service                 Address
------                      -------                 -------
<S>                         <C>                     <C>

CBM Experts                 Janitorial Contract     1400 Dolley Madison Blvd.
                                                    McLean, VA 22101

Datawatch                   Security Service        4401 East-West Highway
                                                    Suite 500
                                                    Bethesda, MD 20814

Miller Elevator             Elevator Service        5050 Lawrence Place
                                                    Hyattsville, MD 20781

Enterprise Communications   Answering Service       8100 Stansbury Road
                                                    Suite 200
                                                    Baltimore, MD 21222

Mid-Atlantic Power          Emergency Generator     114 Oak Grove Road
Specialists, Inc.                                   Suite 103
                                                    Sterling, VA 22170

EMS Consultants, Inc.       HVAC                    2134 Espey Court, Suite 7
                                                    Crofton, MD 21114

Metrocall                   Pager Service           P.O. Box 79058
                                                    Baltimore, MD 21270-0058

Western Termite             Pest Control            10843 Main Street
                                                    Fairfax, VA 22030

STH, Inc.                   Pump Maintenance        P.O. Box 118
                                                    Gaithersburg, MD 20884

BFI                         Trash Removal           P.O. Box 912011
                                                    Orlando, Fla 32891-2011

Valcourt Building           Window Cleaning         1001 N. Highland Street
Services, Inc.                                      Arlington, VA 22201

</TABLE>