<PAGE>

                                 EXHIBIT 10.16
                                 -------------

                                 COMMON STOCK


                  Minimum Shares:           Maximum Shares:

                     571,424                    952,381



                               ESCROW AGREEMENT


First Citizens Bank & Trust Company
Attn: Darrell V. Milton
Corporate Trust Department - DAC61
Post Office Box 29522
Raleigh, North Carolina 27626-0522

Gentlemen:

This letter will confirm the agreement between the undersigned MainStreet
BankShares, Inc., the holding company, (the "Company") and First Citizens Bank &
Trust Company (the "Escrow Agent"), whereby the Escrow Agent agrees to act as
escrow agent in connection with a subscription offering for a minimum of 571,424
shares and a maximum of 952,381 shares of the Company's common stock, no par
value per share (the "Shares"), which will be sold for an aggregate purchase
price of $10.50 per share. The offer and sale of the Shares (the "Offering) will
be made pursuant to an Offering Circular dated August 22, 2001.

Pursuant to the Offering Circular, prospective investors who desire to subscribe
for Shares (the "Subscribers") will submit written subscription agreements
("Subscription Offers") substantially in the form accompanying the Offering
Circular. Under the terms of the Offering, each Subscription Offer must be
accompanied by payment in the full amount of $10.50 per Share subscribed (the
"Expense Deposit"). Subscription Offers will be accepted through the date set
forth on Exhibit A hereto as the Expiration Date (the "Expiration Date"), which
date may be extended by the Company until the date set forth on Exhibit A hereto
as the Extended Expiration Date. The Offering may be closed, terminated and/or
withdrawn prior to the Expiration Date as described in the Offering Circular.

In connection with the foregoing, and the Escrow Agent's indicated willingness
to provide services in connection with the Offering as described herein, and in
confirmation of the terms of this escrow arrangement, the parties hereto agree
as follows:

           1.  Receipt and Delivery of Payments for Subscribed Shares. In
               ------------------------------------------------------
               connection with the Offering, and as described in the Offering
               Circular, the Subscribers will be instructed to make all checks
               or money orders delivered with a Subscription Offer as an Expense
               Deposit, or otherwise delivered in payment of the balance of the
               Purchase Price of Shares, payable to, and to forward the same
               with their executed Subscription Offers to, MainStreet
               BankShares, Inc. Escrow Account.

           2.  Escrow Account. All funds delivered to or received by the Company
               --------------
               as set forth above will be received and then given to the escrow
               agent in a separate and distinct escrow
<PAGE>

               account entitled "Escrow Account for the Benefit of Subscribers
               for the Shares of MainStreet BankShares, Inc. (the "Escrow
               Account").

           3.  Release of Escrowed Funds.
               -------------------------

               (a)  Subject to the other terms and conditions of this Agreement,
                    within two (2) business days following receipt by the Escrow
                    Agent of the written request of the Company's President, the
                    Escrow Agent shall deliver to the Company (i) the entire
                    amount of such Expense Deposits as shall have been deposited
                    to and remain on deposit in the Escrow Account (or such
                    lesser amount thereof as shall have been specified in the
                    written request), or (ii) the entire amount of payments for
                    the balance of the Purchase Price of Shares as shall have
                    been deposited to and remain on deposit in the Escrow
                    Account (or such lesser amount thereof as shall have been
                    specified in the written request).

                    However, notwithstanding anything contained herein to the
                    contrary, no funds shall be released to the Company unless
                    (i) there has been delivered to the Escrow Agent a copy of
                    correspondence received from the Office of the Comptroller
                    of the Currency and the Federal Deposit Insurance
                    Corporation to the effect that the Bank's charter has been
                    preliminarily approved and deposit insurance application has
                    been approved and from the Federal Reserve and Virginia
                    Bureau of Financial Institutions approving the Company's
                    ownership of Bank; (ii) the written request for such release
                    of funds contains or is accompanied by the written
                    certification of the Company's President that Subscription
                    Offers have been received and accepted for at least 547,600
                    Shares, (iii) the Escrow Agent shall have independently
                    determined that collected funds have been deposited in the
                    Escrow Account (including Expense Deposits and payments of
                    the balance of the Purchase Price of Shares, but excluding
                    any such funds that have been refunded to subscribers) in an
                    aggregate amount of at least $5,749,800, and (iv) the Escrow
                    Agent's fees and charges imposed hereunder to the date of
                    such proposed release of funds have been paid or otherwise
                    provided for the Escrow Agent's satisfaction.

               (b)  If: (i) on the Expiration Date of the Offering (as such date
                    may be extended as provided in the Offering Circular), there
                    have not been delivered to the Escrow Agent copies of
                    Subscription Offers for at least 571,424 Shares and deposits
                    to the Escrow Account of collected funds representing the
                    aggregate Purchase Price therefor (an aggregate of
                    $5,999,952) or (ii) the Escrow Agent receives written notice
                    from the Company's President that the Offering has otherwise
                    been terminated or withdrawn with no Shares to be sold, or,
                    (iii) the Escrow Agent receives written notices from the
                    Company's President from time to time that certain specified
                    Subscription Offers will be rejected or accepted for a
                    lesser number of Shares than the number for which the
                    Purchase Price has been received, then the Escrow Agent
                    shall promptly thereafter return the escrowed funds (or the
                    appropriate portion thereof related to such specified
                    Subscription Offers) without any deduction for expenses,
                    charges or fees, to the Subscribers entitled thereto. Such
                    payments to Subscribers shall be made by Escrow Agent's
                    check mailed to the Subscribers at their addresses listed in
                    the Subscription Offers. The Company's President agrees to
                    give the Escrow Agent notice of any extension of the
                    Expiration Date prior to such date.

           4.  Investment of Funds. The Escrow Agent shall invest and reinvest
               -------------------
               the Escrow Funds, as MainStreet BankShares, Inc., shall direct
               (subject to any applicable minimum investment requirements), in
               the following:
<PAGE>

               (a)  Direct obligations of the United States of America or
                    obligations the principal and the interest on which are
                    unconditionally guaranteed by the Untied States of America;
                    or
               (b)  Certificates of deposit issued by any bank, bank and trust
                    company, or national banking association (including the
                    Escrow Agent and its affiliates), which certificates of
                    deposit are insured by the Federal Deposit Insurance
                    Corporation or a similar government agency; or
               (c)  Any money market fund substantially all of which is invested
                    in the foregoing categories, including any money market fund
                    managed by the Escrow Agent and any of its affiliates.

               If the Escrow Agent has not received a written direction from
          MainStreet BankShares, Inc. at any time that an investment decision
          must be made, the Escrow Agent shall invest the Escrow Funds, or such
          portion thereof as to which no written direction has been received, in
          investments described in clause (c) above.

               Each of the foregoing investments shall be made in the name of
          the Escrow Agent. No investment shall be made in any instrument or
          security that has a maturity of greater than thirty (30) days.
          Notwithstanding anything to the contrary contained herein, the Escrow
          Agent may, without notice to MainStreet BankShares, Inc. sell or
          liquidate any of the foregoing investments at any time if the proceeds
          thereof are required for any release of funds permitted or required
          hereunder, and the Escrow Agent shall not be liable or responsible for
          any loss, cost, or penalty resulting from any such sale or
          liquidation. With respect to the funds received by the Escrow Agent
          for deposit in to the Escrow Funds or any written direction from
          MainStreet BankShares, Inc. received by the Escrow Agent with respect
          to investment of any funds received by the Escrow Agent for deposit
          into the Escrow Funds or any written direction from MainStreet
          BankShares, Inc. received by the Escrow Agent with respect to
          investment of any funds in the Escrow Funds after 10:00 A.M., Eastern
          Standard time, the Escrow Agent shall not be required to invest such
          funds or to effect such investment instruction until the next day upon
          which banks in Raleigh, North Carolina are open for business.

               The Escrow Agent shall not be liable or responsible for any loss
          resulting from any investment made in accordance with the provisions
          of this Agreement or made pursuant to instructions from or with the
          consent of MainStreet BankShares, Inc.

          5. Interest on Escrowed Funds. At such time as the Escrow Account
             --------------------------
             shall be closed and Escrow Agent shall deliver all escrowed funds
             remaining in the Escrow Account to the Company, or shall return all
             such funds to Subscribers, as provided in Paragraph 3 above, it
             also shall deliver or make available to the Company any and all
             interest or income earned to date or such funds. All interest or
             other income earned or paid on funds in the Escrow Account shall
             belong to the Company.

          6. Fees and Expenses of the Escrow Agent. MainStreet BankShares, Inc.
             -------------------------------------
             shall compensate the Escrow Agent for its services hereunder in
             accordance with Exhibit A attached hereto and in addition shall
             reimburse the Escrow Agent for all its reasonable out-of-pocket
             expenses, including attorney's fees, travel expenses, telephone and
             facsimile transmission costs, postage (including express mail and
             overnight charges), copying charges, litigation expenses,
             arbitration costs and the like. All of the compensation and
             reimbursement obligations shall be payable by MainStreet
             BankShares, Inc. Escrow Agent shall have a lien on the Escrow Funds
             and/or Property, in preference to all other claims and release
             obligations, for the payment of all such fees, expenses, and costs.
<PAGE>

         7.  Liability of Escrow Agent. The Escrow Agent shall have no liability
             -------------------------
             or obligation for damages, loss or expenses with respect to the
             Escrow Funds except for damages, loss or expenses resulting from
             the Escrow Agent's willful conduct or gross negligence or breach of
             this contract. The Escrow Agent's sole responsibility shall be for
             the safekeeping, investment and disbursement of Escrow Funds in
             accordance with the terms of this Escrow Agreement. The Escrow
             Agent's duties are entirely administrative, not discretionary. The
             Escrow Agent shall have no implied duties or obligations forth
             herein and shall not be charged with knowledge or notice of any
             fact or circumstance not specifically set forth herein. The Escrow
             Agent shall have no responsibility not specifically provided herein
             and shall not be responsible for anything done or omitted to be
             done by it, except for its own willful misconduct, gross negligence
             or breach of this contract. The Escrow Agent shall have no
             liability for following any instructions given pursuant to this
             Escrow Agreement or set forth in any court or administrative order.
             The Escrow Agent may rely upon any instrument, not only as its due
             execution, validity and effectiveness, but also as to the truth and
             accuracy of any information contained herein, which the Escrow
             Agent shall in good faith believe to be genuine, to have been
             signed or presented by the Person or Parties purporting to sign the
             same and conform to the provisions of this Escrow Agreement. The
             Escrow Agent shall have no responsibility for verifying the
             genuineness, correctness, or competence of any such instrument. In
             no event shall the Escrow Agent be liable for incidental, indirect,
             special, consequential or punitive damages. The Escrow Agent shall
             not be obligated to take any legal action or commence any
             proceeding in connection with the Escrow Funds, any account in
             which Escrow Funds are deposited. The Escrow Agent may, but shall
             not be required to, consult legal counsel selected by it in the
             event of any dispute or question as to the construction of any of
             the provisions hereof or of any other agreement or of its duties
             hereunder, and shall incur no liability and shall be fully
             indemnified from any liability whatsoever in acting in accordance
             with the opinion or instructions of such counsel. MainStreet
             BankShares, Inc. shall pay promptly to the Escrow Agent upon demand
             the reasonable fees and expense of such counsel.

             The Escrow Agent may refrain from taking any action, other than
             keeping the Escrow Funds in escrow, if (i) it is uncertain
             concerning its duties or rights under this Escrow Agreement or
             under any laws or regulations that might affect or override the
             terms herein; or (ii) it receives conflicting claims or demands
             concerning this Escrow Agreement from any person or entity; or
             (iii) it receives instructions that might be in conflict with any
             of the terms of this Escrow Agreement.

             The Escrow Agent, except as herein specifically provided for, is
             not a party to, nor is it bound by or need it give consideration to
             the terms or provisions of any other agreement or undertaking
             between MainStreet BankShares, Inc., and the Escrow Agent is
             obligated to give consideration only to the terms and provisions of
             this Agreement. Unless specifically proved herein, the Escrow Agent
             has no duty to determine or inquire into the happening or
             occurrence of any event or contingency or the performance or
             failure of performance of any party, person, or entity.

         8.  Indemnification. From and at all times after the date of this
             ---------------
             Escrow Agreement, MainStreet BankShares, Inc. shall to the fullest
             extent permitted by law and to the extent provided herein,
             indemnify and hold harmless the Escrow Agent and each director,
             officer, employee, attorney, agent and Affiliate of the Escrow
             Agent against any and all actions, claims losses, damages,
             liabilities, costs and expenses, including reasonable attorneys'
             fees and litigation expenses, of any kind or nature whatsoever
             incurred by or asserted against it except those for which Escrow
             Agent is liable under Section F. The indemnification obligations of
             MainStreet BankShares, Inc. shall survive the termination of this
             Agreement.
<PAGE>

          9. Interpleader. In the event any disagreement or dispute arises under
             ------------
             this Escrow Agreement, or in the event adverse claims or demands
             are made in connection with this Agreement or any property involved
             herein or affected hereby, the Escrow Agent may petition any court
             of competent jurisdiction to resolve the disagreement or dispute or
             adverse claims or demands. In connection therewith, the Escrow
             Agent may (but shall not be required to) tender into the custody of
             the court all money of property in its hands under the terms of
             this Escrow Agreement, and thereupon be discharged from all further
             duties under this Escrow Agreement. The filing of any such legal
             proceeding shall no deprive Escrow Agent of its compensation earned
             prior to such filing. MainStreet BankShares, Inc. shall be
             responsible for all costs, expenses and attorneys' fees relating to
             any such action.

         10. Protection of Escrow Agent. The Escrow Agent is authorized to
             --------------------------
             comply with orders issued or process entered by any court with
             respect to the Escrow Fund, without determination by the Escrow
             Agent of such court's jurisdiction in this matter. If the Escrow
             Fund or any portion is at any time attached or levied upon under
             any court order, or if the payment, assignment, transfer or
             delivery of any such property shall be stayed or enjoined by any
             court order, or in case any order, judgment or decree shall be made
             or entered by any court affecting such property, then and in any
             such event, the Escrow Agent is authorized to rely upon and comply
             with any such order, judgment or decree without the need for appeal
             or other action; and if the Escrow Agent complies with any such
             order, judgment or decree, it shall not be liable to any party
             hereto or to any other person or entity by reason of such
             compliance even if such order, judgment or decree is subsequently
             reverse, modified, set aside or vacated.

         11. Notices and Communications. All notices and communications
             --------------------------
             hereunder shall be in writing and shall be deemed duly given if
             sent by U. S. mail, postage prepaid, or by hand delivery, to the
             following parties:

             The Escrow Agent:     First Citizens Bank and Trust Company
                                   Attn: Darrell V. Milton
                                   Corporate Trust Department - DAC61
                                   Post Office Box 29522
                                   Raleigh, North Carolina 27626-0522

             The Company:          MainStreet BankShares, Inc.
                                   730 E. Church Street, Suite #12
                                   P.O. Box 1224
                                   Martinsville, Virginia 24114-1224

         12. Resignation and Removal of the Escrow Agent. The Escrow Agent may
             -------------------------------------------
             resign from the performance of its duties hereunder at any time by
             giving thirty (30) days prior written notice to MainStreet
             BankShares, Inc., or may be removed, with or without cause, by
             MainStreet BankShares, Inc. acting jointly by furnishing a Joint
             Written Direction to the Escrow Agent, at any time by the giving of
             thirty (30) days prior written notice to the Escrow Agent. Such
             resignation or removal shall take effect upon the appointment of a
             successor Escrow Agent as provided herein. Upon any such notice of
             resignation or removal, MainStreet BankShares, Inc. shall appoint a
             successor Escrow Agent hereunder. If such designation of the
             successor Escrow Agent is not made within thirty (30) days after
             the Escrow Agent sends its notice of resignation, the Escrow Agent
             may apply to a court of competent jurisdiction to appoint a
             successor Escrow Agent. Upon the acceptance in writing of any
             appointment as the Escrow Agent hereunder by a successor Escrow
             Agent, such successor Escrow Agent shall thereupon succeed to and
             become vested with all the rights, powers, privileges, and duties
             of the retiring Escrow Agent, and the retiring Escrow Agent shall
             be discharged from its duties and obligations under this Escrow
             Agreement, but shall not be discharged from any liability for
             actions taken as the
<PAGE>

                 Escrow Agent hereunder prior to such succession. After any
                 retiring Escrow Agent's resignation or removal, the provisions
                 of this Escrow Agreement shall inure to its benefit as to any
                 actions taken or omitted to be taken while it was the Escrow
                 Agent under this Escrow Agreement.

             13. General.
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                 (a)  This Agreement shall be binding upon, inure to the benefit
                      of, and be enforceable by the parties and their respective
                      successors and assigns.
                 (b)  This Agreement contains the entire agreement of the
                      parties with respect to the subject manner hereof and may
                      be amended only by an agreement in writing duly signed by
                      the parties hereto
                 (c)  This Agreement will be governed by and construed in
                      accordance with the laws of North Carolina.
                 (d)  This Agreement will remain in full force and effect until
                      the Escrow Agent has disbursed the entire escrowed funds
                      in accordance with the terms hereof.
                 (e)  This Agreement may be executed in duplicate, any one copy
                      of which shall be deemed to be an original.

     If the foregoing correctly sets forth the understanding between the Company
and the Escrow Agent, please indicate the Company's and the Escrow Agent's
acceptance thereof in the space provided below for that purpose.
<PAGE>

                                   EXHIBIT A
                                   ---------

The subscriber information be delivered to First Citizens in a diskette format
that can be readily accessed by First Citizens, the following fee will be in
effect:

The greater of $2,000 or $5.00 per Subscription Offer for which any funds are
deposited to the Escrow Account. Fees shall be payable at the time the Escrow
Account is closed and all remaining funds are released to the bank or returned
to the Subscribers.
<PAGE>

ACCEPTED AND AGREED TO as of this 17/th/ day of August, 2001.



FIRST CITIZENS BANK & TRUST COMPANY
                (Escrow Agent)


By:     Darrell V. Milton
        -----------------


Title:  Vice President
        --------------



ACCEPTED AND AGREED TO as of this 16/th/ day of August, 2001.



MAINSTREET BANKSHARES, INC.
        (Company)


By:     Brenda H. Smith
        ---------------


Title:  Senior Vice President/CFO
        -------------------------