Exhibit 10.6


MEZZANINE PROMISSORY NOTE


	
  $20,000,000.00

  	
   

  	
  New York, New York

  
	
   

  	
   

  	
  June 8, 2007

  



 


FOR VALUE RECEIVED,  BEHRINGER HARVARD SANTA
CLARA M, LLC, a
Delaware limited liability company, having an office at 15601 Dallas
Parkway, Suite 600, Addison, Texas 75001, as maker (“Borrower”), hereby
unconditionally promises to pay to the order of CITIGROUP
GLOBAL MARKETS REALTY CORP., a New York corporation, having its
place of business at 388 Greenwich Street, 11th Floor, New York, NY 10013, , as
payee (“Lender”), or at such other place as the holder hereof may from time to
time designate in writing, the principal sum of TWENTY- MILLION  AND 00/100 DOLLARS ($20,000,000.00), in
lawful money of the United States of America with interest thereon to be
computed from the date of this Note at the Applicable Interest Rate, and to be
paid in accordance with the terms of this Note and that certain Mezzanine Loan
Agreement, dated the date hereof, between Borrower and Lender (the “Loan
Agreement”).  All capitalized terms not
defined herein shall have the respective meanings set forth in the Loan
Agreement.


ARTICLE 1 - PAYMENT TERMS


Borrower agrees to pay the principal sum of this Note
and interest on the unpaid principal sum of this Note from time to time
outstanding at the rates and at the times specified in Article 2 of the Loan
Agreement and the outstanding balance of the principal sum of this Note and all
accrued and unpaid interest thereon shall be due and payable on the Maturity
Date.


ARTICLE 2 - DEFAULT AND ACCELERATION


The Debt shall without notice become immediately due
and payable at the option of Lender if any payment required in this Note is not
paid on or prior to the date when due (subject to any applicable grace or cure
period applicable to such payment under any Loan Document) or if not paid on
the Maturity Date or on the happening of any other Event of Default and in
addition, Lender shall be entitled to receive interest on the entire unpaid
principal sum at the Default Rate pursuant to the terms of the Loan
Agreement.  This Article 2, however,
shall not be construed as an agreement or privilege to extend the date of the
payment of the Debt, nor as a waiver of any other right or remedy accruing to
Lender by reason of the occurrence of any Event of Default.


ARTICLE 3 - LOAN DOCUMENTS


This Note is secured by the Pledge Agreement and the
other Loan Documents.  All of the terms,
covenants and conditions contained in the Loan Agreement, the Pledge Agreement
and the other Loan Documents are hereby made part of this Note to the same
extent and with the same force as if they were fully set forth herein.  In the event of a conflict or inconsistency
between the terms of this Note and the Loan Agreement, the terms and provisions
of the Loan Agreement shall govern.













ARTICLE 4 - SAVINGS CLAUSE


This Note and the Loan Agreement are subject to the
express condition that at no time shall Borrower be obligated or required to
pay interest on the principal balance of the Loan at a rate which could subject
Lender to either civil or criminal liability as a result of being in excess of
the Maximum Legal Rate.  If, by the terms
of this Note, the Loan Agreement or the other Loan Documents, Borrower is at
any time required or obligated to pay interest on the principal balance due
hereunder at a rate in excess of the Maximum Legal Rate, the Applicable
Interest Rate or the Default Rate, as the case may be, shall be deemed to be
immediately reduced to the Maximum Legal Rate and all previous payments in
excess of the Maximum Legal Rate shall be deemed to have been payments in
reduction of principal and not on account of the interest due hereunder.  All sums paid or agreed to be paid to Lender
for the use, forbearance, or detention of the sums due under the Loan, shall,
to the extent permitted by applicable law, be amortized, prorated, allocated,
and spread throughout the full stated term of the Loan until payment in full so
that the rate or amount of interest on account of the Loan does not exceed the
Maximum Legal Rate of interest from time to time in effect and applicable to
the Loan for so long as the Loan is outstanding.


ARTICLE 5 - NO ORAL CHANGE


This Note may not be modified, amended, waived,
extended, changed, discharged or terminated orally or by any act or failure to
act on the part of Borrower or Lender, but only by an agreement in writing
signed by the party against whom enforcement of any modification, amendment,
waiver, extension, change, discharge or termination is sought.


ARTICLE 6 - WAIVERS


Borrower and all others who may become liable for the
payment of all or any part of the Debt do hereby severally waive presentment
and demand for payment, notice of dishonor, notice of intention to accelerate,
notice of acceleration, protest and notice of protest and non-payment and
all other notices of any kind.  No
release of any security for the Debt or extension of time for payment of this
Note or any installment hereof, and no alteration, amendment or waiver of any
provision of this Note, the Loan Agreement or the other Loan Documents made by
agreement between Lender or any other Person shall release, modify, amend,
waive, extend, change, discharge, terminate or affect the liability of
Borrower, and any other Person who may become liable for the payment of all or
any part of the Debt, under this Note, the Loan Agreement or the other Loan
Documents.  No notice to or demand on
Borrower shall be deemed to be a waiver of the obligation of Borrower or of the
right of Lender to take further action without further notice or demand as
provided for in this Note, the Loan Agreement or the other Loan Documents.  If Borrower is a partnership, the agreements
herein contained shall remain in force and be applicable, notwithstanding any
changes in the individuals or entities comprising the partnership, and the term
“Borrower,” as used herein, shall include any



 2
 









alternate or successor
partnership, but any predecessor partnership and their partners shall not
thereby be released from any liability. 
If Borrower is a corporation, the agreements contained herein shall
remain in full force and be applicable notwithstanding any changes in the
shareholders comprising, or the officers and directors relating to, the
corporation, and the term “Borrower” as used herein, shall include any
alternate or successor corporation, but any predecessor corporation shall not
be relieved of liability hereunder.  If
Borrower is a limited liability company, the agreements herein contained shall
remain in force and be applicable, notwithstanding any changes in the members
comprising the limited liability company, and the term “Borrower” as used
herein, shall include any alternate or successor limited liability company, but
any predecessor limited liability company and their members shall not thereby
be released from any liability.  (Nothing
in the foregoing sentence shall be construed as a consent to, or a waiver of,
any prohibition or restriction on transfers of interests in such partnership,
corporation or limited liability company which may be set forth in the Loan
Agreement, the Pledge Agreement or any other Loan Document.)  If Borrower consists of more than one person
or party, the obligations and liabilities of each such person or party shall be
joint and several.


ARTICLE 7 - TRANSFER


Upon the transfer of this Note, Borrower hereby
waiving notice of any such transfer, Lender may deliver all the collateral
mortgaged, granted, pledged or assigned pursuant to the Loan Documents, or any
part thereof, to the transferee who shall thereupon become vested with all the
rights herein or under applicable law given to Lender with respect thereto, and
Lender shall thereafter forever be relieved and fully discharged from any
liability or responsibility in the matter; but Lender shall retain all rights
hereby given to it with respect to any liabilities and the collateral not so
transferred.


ARTICLE 8 - EXCULPATION


Notwithstanding anything to the contrary contained in
this Note, the liability of Borrower to pay the Debt and for the performance of
the other agreements, covenants and obligations contained herein and in the
Pledge Agreement, the Loan Agreement and the other Loan Documents shall be
limited as set forth in Section 10.1 of the Loan Agreement.


ARTICLE 9 - GOVERNING LAW


This Note shall be governed in accordance with the
terms and provisions of Section 10.6 of the Loan Agreement.


ARTICLE 10 - NOTICES


All notices or other written communications hereunder
shall be delivered in accordance with Section 6.1 of the Loan Agreement.


[NO
FURTHER TEXT ON THIS PAGE]



 3














IN WITNESS WHEREOF,
Borrower has duly executed this Note as of the day and year first above
written.