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                                                                  Exhibit 10.99

                      PROMISSORY NOTE AND LOAN AGREEMENT

Principal Sum: $2,908,230.00                        Date: as of January 30, 1998
                                                              New York, New York

            FOR VALUE RECEIVED, MARKET SQUARE DEVELOPMENT INVESTORS ("Maker"), a
District of Columbia limited partnership, promises to pay to CORNERSTONE MARKET
SQUARE LLC ("Payee"), a Delaware limited liability company having an office at
126 East 56th Street, New York, New York 10022, or to order, or at such other
place as may be designated hereof, the principle sum of TWO MILLION NINE HUNDRED
EIGHT THOUSAND TWO HUNDRED THIRTY AND NO/100 DOLLARS ($2,908,230.00) with
interest thereon, or on the amount thereof from time to time outstanding, to be
computed as hereinafter provided, until the said principal sum shall be fully
paid, to be due and payable as provided. The said principal sum, or the amount
thereof outstanding, with accrued and unpaid interest thereon, shall be due and
payable on the Maturity Date (as hereinafter defined).

            1. Interest. Interest shall accrue from the date hereof up to and
through the date on which all principle and interest hereunder, is paid in full,
shall be computed on the basis of actual days elapsed in a 365-day year, and
shall be calculated on the outstanding principal balance hereunder at an annual
rate of interest equal to eleven percent (11%) percent per annum (the"Interest
Rate") .

            2. Installments.

                  a. No installments of interest or principal shall be payable
under this Note for the period commencing on the date hereof and ending on
August 1, 1999 (the "Deferral End Date"). During such period, all interest on
this Note shall accrue and, to the extent permitted by law, such accrued and
unpaid interest shall bear interest at the Interest Rate, compounded monthly.

                  b. Installments of principal and interest at the Interest Rate
(the "Installment Payments"), in the amount necessary to amortize in equal
monthly payments the sum of (a) the then-outstanding principal sum hereof and
(b) the amount of all interest accrued and deferred pursuant to the preceding
sentence as of the Deferral End Date, and the interest accrued thereon as of
Deferral End Date, less any sums paid on account of such accrued and deferred
interest and on account of principal as hereinafter provided, together with
interest on such sum, over a period of twenty (20) years (the "Amortization
Period"), shall be due and payable commencing on September 1, 1999 and
continuing on the first day of each and every calendar month thereafter ensuing
until September 1, 2002 (the "Maturity Date"), at which time the entire
outstanding principal sum hereof, all accrued interest and all other sums due
and payable hereunder shall be fully paid. Payee shall calculate the amount of
such installments and give notice thereof to Maker. Payee's calculation of the
amount of such installments shall be definitive absent manifest error.
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                  c. Maker agrees that in the event that Maker has any net cash
flow from any source after payment of any amounts due under that certain
Promissory Note and Loan Agreement dated August 15, 1997, from Maker, as "Maker"
therein, to DIHC Finance Corporation, as "Payee" therein, in the original
principal amount of up to $41,900,000.00, which loan has been assigned to
Cornerstone Properties Limited Partnership, such net cash flow shall be applied
first on account of any interest accrued and deferred hereunder; second, on
account of any Installment Payments then due hereunder; and third, on account of
the outstanding principal amount of this Note, prior to being used for any other
purpose.

                  d. Payee expressly acknowledges that (i) in no event shall the
obligations of Maker under this Note or the Security Documents (as hereinafter
defined) be enforced against DIHC Market Square Inc. ("DIHC-MS"), any interest
of DIHC-MS in Maker, or any shareholder, officer, director or agent of DIHC-MS
(collectively, the "Exculpated Parties") and (ii) payee shall not seek any
judgment against the Exculpated Parties in respect of this Note, the Security
Documents or otherwise relating to the indebtedness evidenced hereby.

            3. Default Interest Rate. In the event Maker fails to pay any
installment of principal or interest within ten (10) days after its due date,
the unpaid amount shall accrue interest at the rate (the "Default Rate") equal
to the lesser of (a) five percent (5%) in excess of the "prime rate" announced
from time to time by Bankers Trust Company at its offices in the City of New
York or (b) the maximum interest rate permitted by law to be charged to Maker
until paid.

            4. Security. Upon the request of Payee, Maker shall deliver (a) to
Payee a pledge of Maker's partnership interest under the joint venture agreement
for Market Square Associates, a District of Columbia general partnership
("MSA"), as security for Maker's obligations under this Note pursuant to a
pledge and security agreement satisfactory to Payee, and (b) such other security
documents as Payee may reasonably request to secure Maker's obligations
hereunder, including, but not limited to, UCC-1 Financing Statements
(collectively, the "Security Documents").

            5. Event of Default. The occurrence of any one of the following
events shall constitute an "Event of Default" hereunder:

                  a. Maker fails to pay any installment of principal or
interest, or any other sum due hereunder, when and as the same shall become due
and payable, and such failure is not cured within fifteen (15) days after
written notice thereof from Payee to Maker;

                  b. Maker, or any endorser makes any assignment for the benefit
of creditors; or a receiver, liquidator or trustee of Maker, or of substantially
all property of Maker or such endorser, is appointed; or any voluntary or
involuntary petition for the bankruptcy, reorganization or arrangement of, or
for the composition, extension, arrangement or adjustment of any of the
obligations of, Maker or such endorser, pursuant to the Federal Bankruptcy Code,
or any similar statute, is filed and not dismissed within sixty (60) days; or
Maker or such endorser


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shall have been adjudicated a bankrupt or insolvent; or any voluntary or
involuntary petition by or against Maker or such endorser, as debtor seeking an
order for relief pursuant to the Federal Bankruptcy Code, or any similar
statute, is pending or filed and not dismissed within sixty (60) days; or a
court enters an order for relief for Maker or such endorser, as debtor; or Maker
or any such endorser, is insolvent by reason of its inability to pay its debts
as they become due; or a writ of attachment is issued against any of the
Property of Maker or such endorser, and not dismissed within sixty (60) days; or
if Possession is taken to assume control of all or any substantial part of such
part of such property or of the business of Maker or such endorser by any
government or governmental agency; and/or

                  c. Any warranty, representation or statement of Maker in this
Note or any of the Security Documents or any other instrument or document now or
hereafter evidencing, securing or otherwise relating to the indebtedness
evidenced by this Note proves untrue or misleading in any material respect; or
Maker fails to keep, observe, and perform any other covenant, agreement,
obligation or condition contained herein, the Security Documents or in any other
instrument or document now or hereafter evidencing or securing the indebtedness
evidenced by this Note or any part thereof, and such untruth, misleading matter,
failure or default is not cured within thirty (30) days after written notice
thereof from Payee to Maker or such additional period as may be reasonably
needed as long as Payee commences the cure of same within the thirty (30)-day
period and thereafter diligently prosecutes the cure to completion.

            6. Rights of Payee upon Default. Upon and after the occurrence of an
Event of Default, it is expressly agreed that the principal sum of this Note
(and all accrued interest thereon and other sums payable hereunder) shall become
immediately due and payable at the option of Payee.

            7. Prepayment. This Note may be prepaid in whole or in part without
fee or penalty (but with accrued interest on the amount so prepaid) at any time
upon not less am ten (10) days' prior written notice by Maker to Payee.

            8. Applicable Law. This Note has been negotiated, executed, made and
delivered in the City, Country and State of New York. Maker agrees that this
Note shall be governed, construed and interpreted in accordance with the laws of
the State of New York.

            9. Waiver.

                  a. Maker and any endorsers, sureties and guarantors hereof or
hereon hereby waive presentment for payment, demand, protest, notice of
non-payment or dishonor and of protest, and agree to remain bound until the
principal sum of this Note or the amount thereof outstanding and interest and
all other sums payable hereunder are paid in full notwithstanding any
extensions of time for payment which may be granted, even though the period of
extension may be indefinite, and notwithstanding any inaction by, or failure to
assert any legal right available to, Payee.


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                  b. It is further expressly agreed that any waiver by Payee,
other than a waiver in writing signed by Payee, of any term or provision hereof,
of the Security Documents or of any right, remedy or option under this Note or
the Security Documents shall not be controlling, nor shall it prevent or estop
Payee from thereafter enforcing such term, provision, right, remedy or option,
and the failure or refusal of Payee to insist in any one or more instances upon
the strict performance of any of the terms or provisions of this Note, or the
Security Documents shall not be construed as a waiver or relinquishment for the
future of any such term or provision, but the same shall continue in full force
and effect, it being understood and agreed that Payee's rights, remedies and
options under this Note and the Security Documents are and shall be cumulative
and are in addition to all other rights, remedies and options of Payee at law or
in equity or under any other agreement.

                  c. No modification or waiver by Payee of any right or remedy
under this Note shall be effective unless made in writing. No delay by Payee in
exercising any right or remedy hereunder, or otherwise afforded by law, shall
operate as a waiver thereof or preclude the exercise thereof upon the occurrence
of an Event of Default. No failure by Payee to insist upon the strict
performance by Maker of each and every covenant and agreement of Maker under
this Note shall constitute a waiver of any such covenant or agreement, and no
waiver by Payee of any Event of Default shall constitute a waiver of or consent
to any subsequent Event of Default. No failure of Payee to exercise its option
to accelerate the maturity of the indebtedness evidenced hereby, nor any
forbearance by Payee before or after the exercise of such option shall be
construed as a waiver of an option, power, right or remedy of Payee hereunder.

            10. Successors. The term "Payee" shall mean the then holder of this
Note from time to time and its successors and permitted assigns.

            11. Costs of Collection. Maker shall pay all costs of collection
when incurred, including, without limitation, the reasonable attorneys' fees and
disbursements of the Payees counsel and court costs, which costs may be added to
the indebtedness evidenced hereby and must be paid promptly on demand, together
with interest thereon at the Default Rate.

            12. Interest Not to Exceed Maximum Allowed by Law. If from any
circumstances whatsoever, the fulfillment of any provision of this Note or of
any other instrument evidencing or securing the indebtedness evidenced hereby,
at the time performance of such provision shall be due, shall involve
transcending the limit of validity presently prescribed by any applicable usury
statute or any other applicable law with regard to obligations of like character
and amount, then ipso facto, the obligation to be fulfilled shall be reduced to
the limit of such validity so that in no event shall any exaction be possible
under this Note or under any other instrument evidencing or securing the
indebtedness evidenced hereby that is in excess of the current limit of
such validity, but such obligation shall be fulfilled to the limit of such
validity. In the event of any such reduction of said obligation, the unpaid
principal balance of this Note together with all accrued interest thereon and
any other sums advanced hereunder or under any instruments securing


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the indebtedness evidenced hereby shall at the option of Payee become
immediately due and payable.

            13. Assignment. Payee's right, title and interest in and to this
Note are freely assignable by Payee to Cornerstone Properties Inc. ("CPP"), or
any affiliate or subsidiary of CPP, without the consent or approval of any
person or entity, and any such assignment hereof by Payee shall operate to vest
in such assignee all rights, titles, interests and powers herein conferred upon
Payee. Notwithstanding the foregoing, Maker acknowledges that Payee may, at any
time and from time to time, sell this Note or any interest herein, pledge or
assign this Note or any interest herein as security in connection with any
financing arrangement and enter into any participation or similar cooperative
arrangements with respect hereto.

            14. Time of the Essence. Time is of the essence with respect to each
and every covenant, agreement and obligation of Maker under this Note.

            15. Successors and Assigns. Each and every covenant, warranty and
agreement of Maker herein, if Maker be more than one, shall be jointly and
severally binding upon and enforceable against Maker, and each of them except as
otherwise provided in this Note. As used herein the terms "Maker" and "Payee"
shall include the Maker and the named Payee and their respective heirs,
executors, administrators, legal representatives, successors, successors in
title and permitted assigns.

            16. Severability. If any provision, paragraph, sentence, clause,
phrase or word of this Note, or the application thereof in any circumstance, is
held invalid or unenforceable, the validity and enforceability of the remainder
of this Note, and of the application of any such provision, paragraph, sentence,
clause, phrase or word in any other circumstance, shall not be affected thereby,
it being intended that all rights, powers and privileges of Payee hereunder
shall be enforceable to the fullest extent permitted by law.

            17. Notices. Any and all notices, elections or demands permitted or
required to be made under this Note (collectively, "Notices") shall be in
writing and shall be delivered personally, or sent by registered or certified
mail, to the other party at the address set forth above, or at such other
address as may be supplied in writing in accordance with the terms of this
paragraph. The date of personal delivery, the third (3rd) business day following
the date of mailing or the first business day following a transmission by
overnight courier, as the case may be, shall be the date of the Notice.

            18. Captions. Titles or captions of articles and paragraphs
contained in this Note are inserted only as a matter of convenience and for
reference, and in no way define, limit, extend or describe the scope of this
Note or the intent of any provision hereof.

            19. Number and Gender. Whenever required by the context, the
singular number shall include the plural and the gender of any pronoun shall
include the other genders.


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            IN WITNESS WHEREOF, Maker has executed this Note as of the 30th day
of January, 1998.

                              "Maker":

                              MARKET SQUARE DEVELOPMENT
                              INVESTORS, a District of Columbia general
                              partnership

                              By: DIHC MARKET SQUARE, INC., a
                                  Georgia corporation, as authorized general
                                  partner

                                  By: _______________________________
                                     Name: __________________________
                                     Title:__________________________


                              By: CORNERSTONE MARKET SQUARE
                                  LLC, a Delaware limited liability company,
                                  as authorized general partner

                                  By: _______________________________
                                     Name: __________________________
                                     Title:__________________________


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