Exhibit 4.16






 


 


 


 


SUPPLEMENTAL
INDENTURE NO. 16


by
and between


HRPT
PROPERTIES TRUST


and


U.S.
BANK NATIONAL ASSOCIATION


as of
March 16, 2006


 


SUPPLEMENTAL
TO THE INDENTURE DATED AS OF JULY 9, 1997


 


 






HRPT
PROPERTIES TRUST


Floating
Rate Senior Notes due 2011






 


 


 


 






 











This SUPPLEMENTAL INDENTURE NO. 16 (this “Supplemental
Indenture”) made and entered into as of as of March 16, 2006 between HRPT
PROPERTIES TRUST, a Maryland real estate investment trust (the “Company”), and U.S. BANK NATIONAL ASSOCIATION, a national
banking association, as trustee (the “Trustee”),


WITNESSETH
THAT:


WHEREAS, the Company and the Trustee are parties to an
Indenture, dated as of July 9, 1997 (the “Indenture”), relating to the Company’s
issuance, from time to time, of various series of debt securities;


WHEREAS, the Company has determined to issue debt
securities known as its Floating Rate Senior Notes due 2011; and


WHEREAS, the Indenture provides that certain terms and
conditions for each series of debt securities issued by the Company thereunder
may be set forth in an indenture supplemental to the Indenture;


NOW, THEREFORE, THIS SUPPLEMENTAL INDENTURE
WITNESSETH:


ARTICLE 1


DEFINED TERMS


Section 1.1             The
following definitions supplement, and, to the extent inconsistent with, replace
the definitions in Section 101 of the Indenture:


“Acquired Debt” means Debt of a Person or entity (i)
existing at the time such Person or entity becomes a Subsidiary or (ii) assumed
in connection with the acquisition of assets from such Person or entity, in
each case, other than Debt incurred in connection with, or in contemplation of,
such Person or entity becoming a Subsidiary or such acquisition.  Acquired Debt shall be deemed to be incurred
on the date of the related acquisition of assets from any Person or entity or
the date the acquired Person or entity becomes a Subsidiary.


“Annual Debt Service” as of any date means the maximum
amount which is expensed in any 12-month period for interest on Debt of the
Company and its Subsidiaries.


“Business Day” means any day other than a Saturday or
Sunday or a day on which banking institutions in the City of New York or in the
city in which the Corporate Trust Office of the Trustee is located, are
required or authorized to close.


“Capital Stock” means, with respect to any Person, any
capital stock (including preferred stock), shares, interests, participation or
other ownership interests (however designated) of such Person and any rights
(other than debt securities convertible into or exchangeable for capital
stock), warrants or options to purchase any thereof.
















“Calculation Agent”
means, initially, the Trustee and thereafter any successor calculation agent
appointed and then acting as provided in Section 2.1(b)(iii) of this
Supplemental Indenture.


“Consolidated Income
Available for Debt Service” for any period means Earnings from Operations of
the Company and its Subsidiaries plus amounts which have been deducted, and
minus amounts which have been added, for the following (without duplication):
(i) interest on Debt of the Company and its Subsidiaries, (ii) provision for
taxes of the Company and its Subsidiaries based on income, (iii) amortization
of debt discount and deferred financing costs, (iv) provisions for gains and
losses on properties and property, depreciation and amortization, (v) the
effect of any noncash charge resulting from a change in accounting principles
in determining Earnings from Operations for such period and (vi) amortization
of deferred charges.


“Corporate Trust Office”
means the corporate trust office of the Trustee which it designates as the
office at which the agreement in question will be administered (which it may
change by notice from time to time), presently located at One Federal Street,
3rd Floor, Boston, Massachusetts 02110.


“Debt” of the Company or
any Subsidiary means, without duplication, any indebtedness of the Company or
any Subsidiary, whether or not contingent, in respect of (i) borrowed money or
evidenced by bonds, notes, debentures or similar instruments, (ii) indebtedness
for borrowed money secured by any Encumbrance existing on property owned by the
Company or any Subsidiary, to the extent of the lesser of (x) the amount of
indebtedness so secured and (y) the fair market value of the property subject
to such Encumbrance, (iii) the reimbursement obligations, contingent or otherwise,
in connection with any letters of credit actually issued (other than letters of
credit issued to provide credit enhancement or support with respect to other
indebtedness of the Company or any Subsidiary otherwise reflected as Debt
hereunder) or amounts representing the balance deferred and unpaid of the
purchase price of any property or services, except any such balance that
constitutes an accrued expense or trade payable, or all conditional sale
obligations or obligations under any title retention agreement, (iv) the
principal amount of all obligations of the Company or any Subsidiary with
respect to redemption, repayment or other repurchase of any Disqualified Stock,
or (v) any lease of property by the Company or any Subsidiary as lessee which
is reflected on the Company’s consolidated balance sheet as a capitalized lease
in accordance with GAAP, to the extent, in the case of items of indebtedness
under (i) through (iii) above, that any such items (other than letters of
credit) would appear as a liability on the Company’s consolidated balance sheet
in accordance with GAAP, and also includes, to the extent not otherwise
included, any obligation by the Company or any Subsidiary to be liable for, or
to pay, as obligor, guarantor or otherwise (other than for purposes of
collection in the ordinary course of business), Debt of another Person (other
than the Company or any Subsidiary) (it being understood that Debt shall be
deemed to be incurred by the Company or any Subsidiary whenever the Company or
such Subsidiary shall create, assume, guarantee or otherwise become liable in
respect thereof).


“Disqualified Stock”
means, with respect to any Person, any Capital Stock of such Person which by
the terms of such Capital Stock (or by the terms of any security into which it
is convertible or for which it is exchangeable or exercisable), upon the
happening of any event or otherwise (i) matures or is mandatorily redeemable,
pursuant to a sinking fund obligation or otherwise (other than Capital Stock
which is redeemable solely in exchange for common stock or shares), (ii) is
convertible into or exchangeable or exercisable for Debt or Disqualified Stock,
or (iii) is redeemable at the option of the Holder thereof, in whole or in part
(other than Capital Stock which is redeemable solely in exchange for common
stock 



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or shares), in
each case on or prior to the stated maturity of the Notes.


“Earnings from Operations”
for any period means net earnings excluding gains and losses on sales of
investments, extraordinary items, gains and losses on early extinguishment of
debt and property valuation losses, as reflected in the financial statements of
the Company and its Subsidiaries for such period, determined on a consolidated
basis in accordance with GAAP.


“Encumbrance” means any mortgage,
lien, charge, pledge or security interest of any kind.


“Interest Payment Date”
has the meaning specified in the form of Note attached as Exhibit A hereto.


“Interest Period” has the
meaning specified in the form of Note attached as Exhibit A hereto.


“Interest Record Date”
has the meaning specified in the form of Note attached as Exhibit A hereto.


“Notes” means the Company’s
Floating Rate Senior Notes due 2011, issued
under this Supplemental Indenture and the Indenture, as amended or supplemented
from time to time.


“Secured Debt” means Debt
secured by any mortgage, lien, charge, pledge or security interest of any kind.


“Subsidiary” means any
corporation or other entity of which a majority of (i) the voting power of the
voting equity securities or (ii) the outstanding equity interests are owned,
directly or indirectly, by the Company or one or more other Subsidiaries of the
Company.  For the purposes of this
definition, “voting equity securities” means equity securities having voting
power for the election of directors, whether at all times or only so long as no
senior class of security has such voting power by reason of any contingency.


“Total Assets” as of any
date means the sum of (i) the Undepreciated Real Estate Assets and (ii) all
other assets of the Company and its Subsidiaries determined in accordance with
GAAP (but excluding accounts receivable and intangibles).


“Total Unencumbered
Assets” means the sum of (i) those Undepreciated Real Estate Assets not subject
to an Encumbrance for borrowed money and (ii) all other assets of the Company
and its Subsidiaries not subject to an Encumbrance for borrowed money
determined in accordance with GAAP (but excluding accounts receivable and
intangibles).


“Undepreciated Real
Estate Assets” as of any date means the cost (original cost plus capital
improvements) of real estate assets of the Company and its Subsidiaries on such
date, before depreciation and amortization, determined on a consolidated basis
in accordance with GAAP.



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“Unsecured Debt” means
Debt which is not secured by any of the properties of the Company or any
Subsidiary.


ARTICLE
2


TERMS
OF THE NOTES


Section 2.1             Pursuant to Section 301 of the
Indenture, the Notes shall have the following terms and conditions:


(a)           Title;
Aggregate Principal Amount; Form of Notes. 
The Notes shall be Registered Securities under the Indenture and shall
be known as the Company’s “Floating Rate Senior Notes due 2011.”  The Notes will be limited to an aggregate
principal amount of $400,000,000, subject to the right of the Company to reopen
such series for issuances of additional securities of such series and except as
provided in this Section or in Section 306 of the Indenture.  The Notes (together with the Trustee’s
certificate of authentication) shall be substantially in the form of Exhibit A
hereto, which is hereby incorporated in and made a part of this Supplemental
Indenture.


The Notes will be issued
in the form of one or more registered global securities without coupons (“Global
Notes”) that will be deposited with, or on behalf of, The Depository Trust
Company (“DTC”), and registered in the name of DTC’s nominee, Cede &
Co.  Except under the circumstance
described below, the Notes will not be issuable in definitive form.  Unless and until it is exchanged in whole or
in part for the individual Notes represented thereby, a Global Note may not be
transferred except as a whole by DTC to a nominee of DTC or by a nominee of DTC
to DTC or another nominee of DTC or by DTC or any nominee of DTC to a successor
depositary or any nominee of such successor.


So long as DTC or its
nominee is the registered owner of a Global Note, DTC or such nominee, as the
case may be, will be considered the sole owner or holder of the Notes
represented by such Global Note for all purposes under this Supplemental
Indenture.  Except as described below,
owners of beneficial interest in Notes evidenced by a Global Note will not be
entitled to have any of the individual Notes represented by such Global Note
registered in their names, will not receive or be entitled to receive physical
delivery of any such Notes in definitive form and will not be considered the
owners or holders thereof under the Indenture or this Supplemental Indenture.


If DTC is at any time
unwilling, unable or ineligible to continue as depositary and a successor
depositary is not appointed by the Company within 90 days, the Company will
issue individual Notes in exchange for the Global Note or Global Notes
representing such Notes.  In addition,
the Company may at any time and in its sole discretion, subject to certain
limitations set forth in the Indenture, determine not to have any of such Notes
represented by one or more Global Notes and, in such event, will issue
individual Notes in exchange for the Global Note or Global Notes representing
the Notes.  Individual Notes so issued
will be issued in denominations of $1,000 and integral multiples thereof.


(b)           Interest; Calculation Agent.



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(i)            The outstanding principal amount of
the Notes will bear interest at the rate per annum specified in the form of
Note attached as Exhibit A hereto. 
Interest will accrue from March 16, 2006 (or, if this Note was issued
upon any reopening of this series of Notes, from the date designated by the
Company in connection with such reopening), or from the most recent Interest
Payment Date to which interest had been paid or provided for; provided, that if an Interest Payment Date
(other than the maturity date) for this Note falls on a day that is not a
Business Day, the Interest Payment Date shall be postponed to the next
succeeding Business Day unless such next succeeding Business Day would be in
the following month, in which case, the Interest Payment Date shall be the
immediately preceding Business Day.  Cash
interest shall be payable quarterly in arrears on each Interest Payment Date,
commencing June 16, 2006, to the Persons in whose names the Notes are
registered in the Security Register at the close of business on the Interest
Record Date next preceding such Interest Payment Date.  Interest will be computed on the basis of the
actual number of days in an Interest Period and a 360-day year.


(ii)           The interest rate for each Interest
Period will be determined by the Calculation Agent in accordance with the form
of Note attached as Exhibit A hereto. 
Promptly upon determination of the interest rate for an Interest Period,
the Calculation Agent will inform the Trustee and the Company thereof.  Upon request from any Holder of Notes, the
Calculation Agent will provide the interest rate in effect for the Notes for
the current Interest Period and, if it has been determined, the interest rate
to be in effect for the next Interest Period. 
Absent manifest error, each determination of the interest rate by the
Calculation Agent shall be binding and conclusive on the Holders and any
beneficial owners of Notes, the Trustee and the Company.


(iii)          Initially, the Trustee will act as
Calculation Agent.  The Issuer may change
any Calculation Agent by notice of the appointment of a successor Calculation
Agent to the Trustee and without notice to the Holders of Notes.


(c)           Principal
Repayment; Currency.  The stated
maturity of the Notes is March 16, 2011;
provided, however, the Notes may be earlier redeemed at the option of
the Company as provided in paragraph (d) below. 
The principal of each Note payable on its maturity date shall be paid
against presentation and surrender thereof at the Corporate Trust Office of the
Trustee in such coin or currency of the United States of America as at the time
of payment is legal tender for the payment of public or private debts.  The Company will not pay Additional Amounts
(as defined in the Indenture) on the Notes.


(d)           Redemption at the
Option of the Company; Acceleration. 
The Notes will be subject to redemption on any Interest Payment Date
occurring on or after September 16, 2006 at the option of the Company, in
whole or in part, upon not less than 30 nor more than 60 days’ notice to each
Holder of Notes to be redeemed at its address appearing in the Security
Register, at a price equal to the sum of the outstanding principal amount of
the Notes being redeemed, plus accrued and unpaid interest to but excluding the
applicable Redemption Date.


(e)           Notices.  All notices and other communications
hereunder shall be in writing and shall be deemed to have been duly given if
mailed or transmitted by any standard form of telecommunication.  Notices to the Company shall be directed to
it at 400 Centre Street, Newton, 



 5
 









Massachusetts
02458, Attention: President; notices to the Trustee shall be directed to it at
One Federal Street, 3rd Floor, Boston, Massachusetts 02110, Attention:
Corporate Trust Department, Re: HRPT Properties Trust Floating Rate Senior
Notes due 2011; or as to either
party, at such other address as shall be designated by such party in a written
notice to the other party.


(f)            Global
Note Legend.  Each Global Note shall
bear the following legend on the face thereof:


UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED
REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION (“DTC”),
TO THE ISSUER OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT,
AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN
SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY
PAYMENT IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN
AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR
VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED
OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.


(g)           Applicability
of Discharge, Defeasance and Covenant Defeasance Provisions.  The Discharge, Defeasance and Covenant
Defeasance provisions in Article Fourteen of the Indenture will apply to the
Notes.


ARTICLE
3


ADDITIONAL
COVENANTS


Section 3.1             In addition to the covenants of the
Company set forth in Article Ten of the Indenture, for the benefit of the
Holders of the Notes:


(a)           Limitations
on Incurrence of Debt.


(i)            The Company will
not, and will not permit any Subsidiary to, incur any Debt if, immediately after
giving effect to the incurrence of such additional Debt and the application of
the proceeds thereof, the aggregate principal amount of all outstanding Debt of
the Company and its Subsidiaries on a consolidated basis determined in
accordance with GAAP is greater than 60% of the sum (“Adjusted Total Assets”)
of (without duplication) (A) the Total Assets of the Company and its
Subsidiaries as of the end of the calendar quarter covered in the Company’s
Annual Report on Form 10-K, or the Quarterly Report on Form 10-Q, as the case
may be, most recently filed with the Securities and Exchange Commission (or, if
such filing is not permitted under the Securities Exchange Act of 1934, as
amended, with the Trustee) prior to the incurrence of such additional Debt and
(B) the purchase price of any real estate assets or mortgages receivable
acquired, and the amount of any securities offering proceeds received (to the
extent that such proceeds were not used to acquire real estate assets or
mortgages receivable or used to reduce Debt), by the 



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Company or any
Subsidiary since the end of such calendar quarter, including those proceeds
obtained in connection with the incurrence of such additional Debt.


(ii)           In addition to the
foregoing limitations on the incurrence of Debt, the Company will not, and will
not permit any Subsidiary to, incur any Secured Debt if, immediately after
giving effect to the incurrence of such additional Secured Debt and the
application of the proceeds thereof, the aggregate principal amount of all outstanding
Secured Debt of the Company and its Subsidiaries on a consolidated basis is
greater than 40% of Adjusted Total Assets.


(iii)          In addition to the
foregoing limitations on the incurrence of Debt, the Company will not, and will
not permit any Subsidiary to, incur any Debt if the ratio of Consolidated
Income Available for Debt Service to the Annual Debt Service for the four
consecutive fiscal quarters most recently ended prior to the date on which such
additional Debt is to be incurred shall have been less than 1.5 to 1.0, on a
pro forma basis after giving effect thereto and to the application of the
proceeds therefrom, and calculated on the assumption that (A) such Debt
and any other Debt incurred by the Company and its Subsidiaries since the first
day of such four-quarter period and the application of the proceeds therefrom,
including to refinance other Debt, had occurred at the beginning of such
period; (B) the repayment or retirement of any other Debt by the Company
and its Subsidiaries since the first date of such four-quarter period had been
repaid or retired at the beginning of such period (except that, in making such
computation, the amount of Debt under any revolving credit facility shall be
computed based upon the average daily balance of such Debt during such period);
(C) in the case of Acquired Debt or Debt incurred in connection with any
acquisition since the first day of such four-quarter period, the related
acquisition had occurred as of the first day of such period with appropriate adjustments
with respect to such acquisition being included in such pro forma calculation;
and (D) in the case of any acquisition or disposition by the Company or
its Subsidiaries of any asset or group of assets since the first day of such
four-quarter period, whether by merger, stock purchase or sale, or asset
purchase or sale, such acquisition or disposition or any related repayment of
Debt had occurred as of the first day of such period with the appropriate
adjustments with respect to such acquisition or disposition being included in
such pro forma calculation.  If the Debt
giving rise to the need to make the foregoing calculation or any other Debt
incurred after the first day of the relevant four-quarter period bears interest
at a floating rate then, for purposes of calculating the Annual Debt Service,
the interest rate on such Debt shall be computed on a pro forma basis as if the
average interest rate which would have been in effect during the entire such
four-quarter period had been the applicable rate for the entire such period.


(b)           Maintenance
of Total Unencumbered Assets.  The
Company and its Subsidiaries will at all times maintain Total Unencumbered
Assets of not less than 150% of the aggregate outstanding principal amount of
the Unsecured Debt of the Company and its Subsidiaries on a consolidated basis.



 7
 









ARTICLE 4


ADDITIONAL EVENTS OF DEFAULT


Section 4.1             For purposes of this Supplemental
Indenture and the Notes, in addition to the Events of Default set forth in
Section 501 of the Indenture, it shall also constitute an “Event of Default” if
a default under any bond, debenture, note or other evidence of indebtedness of
the Company (including a default with respect to any other series of
securities), or under any mortgage, indenture or other instrument of the Company
under which there may be issued or by which there may be secured or evidenced
any indebtedness for money borrowed by the Company (or by any Subsidiary, the
repayment of which the Company has guaranteed or for which the Company is
directly responsible or liable as obligor or guarantor) having an aggregate
principal amount exceeding $20,000,000, whether such indebtedness now exists or
shall hereafter be incurred or created, which default shall have resulted in
such indebtedness becoming or being declared due and payable prior to the date
on which it would otherwise have become due and payable, without such
indebtedness having been discharged, or such acceleration having been rescinded
or annulled, within a period of ten days after there shall have been given, by
registered or certified mail, to the Company by the Trustee or to the Company
and the Trustee by the Holders of at least 25% in principal amount of the
outstanding Notes, a written notice specifying such default and requiring the
Company to cause such indebtedness to be discharged or cause such acceleration
to be rescinded or annulled and stating that such notice is a “Notice of
Default” hereunder.


ARTICLE
5


EFFECTIVENESS


This Supplemental
Indenture shall be effective for all purposes as of the date and time this
Supplemental Indenture has been executed and delivered by the Company and the
Trustee in accordance with Article Nine of the Indenture.  As supplemented hereby, the Indenture is
hereby confirmed as being in full force and effect.


ARTICLE
6


MISCELLANEOUS


Section 6.1             In
the event any provision of this Supplemental Indenture shall be held invalid or
unenforceable by any court of competent jurisdiction, such holding shall not
invalidate or render unenforceable any other provision hereof or any provision
of the Indenture.


Section 6.2             To the extent that any terms of
this Supplemental Indenture or the Notes are inconsistent with the terms of the
Indenture, the terms of this Supplemental Indenture or the Notes shall govern
and supersede such inconsistent terms.


Section 6.3             This Supplemental Indenture shall
be governed by and construed in accordance with the laws of The Commonwealth of
Massachusetts.


Section 6.4             This Supplemental Indenture may be
executed in several 



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counterparts, each of which shall be an original and all of which shall
constitute but one and the same instrument.


[Remainder of page
intentionally left blank.]



 9
 









IN WITNESS WHEREOF, the
Company and the Trustee have caused this Supplemental Indenture to be executed
as an instrument under seal in their respective corporate names as of the date
first above written.


	
  

  	
  HRPT PROPERTIES TRUST

  
	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
   

  
	
   

  	
  By:

  	
  /s/ John C.
  Popeo

  
	
   

  	
   

  	
  Name:

  	
  John C. Popeo

  
	
   

  	
   

  	
  Title:

  	
  Treasurer and Chief Financial Officer

  
	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
   

  
	
   

  	
  U.S. BANK NATIONAL ASSOCIATION,

  
	
   

  	
  as Trustee

  
	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
   

  
	
   

  	
  By:

  	
  /s/ Marie A.
  Hattinger

  
	
   

  	
   

  	
  Name:

  	
  Marie A. Hattinger

  
	
   

  	
   

  	
  Title:

  	
  Vice President

  
						



 



 10















EXHIBIT A


FORM
OF NOTE


[Face of Note]


Floating Rate Senior Note due 2011




	
  No. R-

  	
   

  	
  $

  






 


HRPT
PROPERTIES TRUST


promises to pay to                                  
or registered assigns, the principal sum of                                     
($           ) on
March 16, 2011, subject to the
terms set forth on the reverse of this Note and the terms of the Indenture
referred to therein.


Interest Payment Dates:                                         each
March 16, June 16, September 16 and December 16, commencing
June 16, 2006 (each, an “Interest
Payment Date”)


Interest Record Dates:                                                 the
Business Day preceding the Interest Payment Date (the “Interest Record Date”).


CUSIP No:


 


	
  

  	
  HRPT PROPERTIES TRUST

  
	
   

  	
   

  
	
   

  	
   

  
	
   

  	
  By:

  	
   

  
	
   

  	
  Name:

  
	
   

  	
  Title:

  
			



 


Attest:


[SEAL]


CERTIFICATE OF AUTHENTICATION


Dated:


This is one of the Notes
referred to in the within-mentioned Indenture:


U.S. BANK NATIONAL ASSOCIATION, as Trustee


	
  By:

  	
   

  	
   

  
	
   

  	
  Authorized Officer

  	
   

  














[THE
FOLLOWING CONSTITUTES THE REVERSE OF THE SECURITY]


HRPT
PROPERTIES TRUST


Floating
Rate Senior Note due 2011


Capitalized terms used herein have the meanings
assigned to them in the Indenture (as defined below) unless otherwise
indicated.


1.             Interest.  HRPT Properties Trust, a Maryland real estate
investment trust (the “Company”), promises to pay interest on the principal
amount of this Note at the rate and in the manner specified below.


(a)           The
interest rate for the initial Interest Period shall be 5.51688% per annum, and
the interest rate for each Interest Period thereafter will be a per annum rate
equal to the sum of (i) three-month LIBOR as determined on the related Interest
Determination Date as provided in this Section, plus (ii) 0.60%.  The Interest Determination Date for an
Interest Period will be the second London Business Day preceding that Interest
Period.


(b)           Interest
on this Note will accrue from March 16, 2006 (or, if this Note was issued upon
any reopening of this series of Notes, from the date designated by the Company
in connection with such reopening), or from the most recent Interest Payment
Date to which interest had been paid or provided for; provided, that if an Interest Payment Date
(other than the maturity date) for this Note falls on a day that is not a
Business Day, the Interest Payment Date shall be postponed to the next
succeeding Business Day unless such next succeeding Business Day would be in
the following month, in which case, the Interest Payment Date shall be the
immediately preceding Business Day.  Cash
interest on this Note is payable quarterly in arrears on each Interest Payment
Date, commencing June 16, 2006.


(c)           An “Interest
Period” is a period commencing on, and including, an Interest Payment Date and
ending on, and including, the day immediately preceding the next Interest Payment
Date with the first Interest Period commencing on March 16, 2006.


(d)           A “London
Business Day” is a Business Day on which dealings in deposits in U.S. dollars
are transacted in the London interbank market.


(e)           On
any Interest Determination Date, LIBOR will be equal to the offered rate for
deposits in U.S. dollars having an index maturity of three months, in amounts
of at least $1,000,000, as such rate appears on “Telerate Page 3750” at
approximately 11:00 a.m., London time, on such Interest Determination
Date.  If on an Interest Determination
Date, such rate does not appear on the “Telerate Page 3750” as of 11:00 a.m.
(London time), or if the “Telerate Page 3750” is not available on such date,
the Calculation Agent will obtain such rate from Bloomberg L.P. page “BBAM.”  If no offered rate appears on “Telerate Page
3750” or Bloomberg L.P. page “BBAM” on an Interest Determination Date at
approximately 11:00 a.m., London time, then the Calculation Agent (after
consultation with the Company) will select four major banks in the London
interbank 



 A-2
 









market (which may include the Calculation Agent in its
individual capacity) and shall request each of their principal London offices
to provide a quotation of the rate at which three-month deposits in U.S.
dollars in amounts of at least $1,000,000 are offered by it to prime banks in
the London interbank market, on that date and at that time, that is
representative of single transactions at that time.  If at least two quotations are provided,
LIBOR will be the arithmetic average of the quotations provided. Otherwise, the
calculation agent will select three major banks (which may include the
Calculation Agent in its individual capacity) in New York City and shall
request each of them to provide a quotation of the rate offered by them at
approximately 11:00 a.m., New York City time, on the Interest Determination
Date for loans in U.S. dollars to leading European banks having an index
maturity of three months for the applicable Interest Period in an amount of at
least $1,000,000 that is representative of single transactions at that time. If
three quotations are provided, LIBOR will be the arithmetic average of the
quotations provided. Otherwise, the rate of LIBOR for the next Interest Period
will be set equal to the rate of LIBOR for the then current Interest Period.


(f)            Dollar
amounts resulting from such calculation will be rounded to the nearest cent,
with one-half cent being rounded upward.


(g)           The
interest rate for each Interest Period will be determined by the Calculation
Agent.  Absent manifest error, each
determination of the interest rate by the Calculation Agent shall be binding
and conclusive on the Holders and any beneficial owners of Notes, the Trustee
and the Company.  Interest will be
computed on the basis of the actual number of days in an interest period and a
360-day year.


(h)           Upon
request from any Holder, the Calculation Agent will provide the interest rate
in effect on the Notes for the current Interest Period and, if it has been
determined, the interest rate to be in effect for the next Interest Period.


2.             Method of Payment.  The Company will pay interest on this Note
(except defaulted interest) on each Interest Payment Date to the Person in
whose name this Note is registered in the Security Register at the close of
business on the Interest Record Date next preceding such Interest Payment
Date.  The Company will pay principal and
interest in money of the United States that at the time of payment is legal
tender for payment of public and private debts. 
The Company, however, may pay principal, premium, if any, and interest
by check payable in such money.  It may
mail an interest check to a Holder’s registered address.


3.             Indenture. 
The Company issued the Notes under an Indenture, dated as of July 9,
1997, and a Supplemental Indenture No. 16 thereto, dated as of March 16,
2006 (collectively, the “Indenture”), between the Company and the Trustee.  The terms of the Notes include those stated
in the Indenture and those made part of the Indenture by reference to the Trust
Indenture Act of 1939 as in effect on the date of the Indenture.  The Notes are subject to all such terms, and
Holders of the Notes are referred to the Indenture and such Act for a statement
of such terms.  The terms of the
Indenture shall govern any inconsistencies between the Indenture and the
Notes.  The Notes are unsecured general
obligations of the Company initially issued in an $400,000,000 aggregate
principal amount.



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4.             Optional Redemption.  The Notes will be subject to redemption on
any Interest Payment Date occurring on or after September 16, 2006 at the
option of the Company, in whole or in part, at a redemption price equal to the
sum of the principal amount of the Notes being redeemed, plus accrued and
unpaid interest to but excluding the applicable Redemption Date.


5.             Mandatory
Redemption.  The Company shall not be
required to make sinking fund or redemption payments with respect to the Notes.


6.             Notice
of Redemption.  Notice of redemption
shall be mailed at least 30 days but not more than 60 days before the
Redemption Date to each Holder of Notes to be redeemed at its registered
address.  Notes may be redeemed in part
but only in whole multiples of $1,000, unless all of the Notes held by a Holder
are to be redeemed.  On and after the
Redemption Date, interest ceases to accrue on Notes or portions of them called
for redemption.


7.             Denominations,
Transfer, Exchange.  The Notes are in
registered form without coupons in denominations of $1,000 and integral
multiples of $1,000 in excess thereof. 
The transfer of Notes may be registered and Notes may be exchanged as
provided in the Indenture.  The Security
Registrar and the Trustee may require a Holder, among other things, to furnish
appropriate endorsements and transfer documents and to pay any taxes and fees
required by law or permitted by the Indenture. 
The Security Registrar need not exchange or register the transfer of any
Note or portion of a Note selected for redemption.  Also, it need not exchange or register the
transfer of any Notes for a period of 15 days before the mailing of a notice of
redemption of Notes, or during the period between a record date and the
corresponding Interest Payment Date.


8.             Defaults
and Remedies.  In case an Event of
Default (as defined in the Indenture) with respect to the Notes shall have
occurred and be continuing, the principal hereof may be declared, and upon such
declaration shall become, due and payable, in the manner, with the effect and
subject to the provisions provided in the Indenture.


9.             Actions
of Holders.  The Indenture contains
provisions permitting the Holders of not less than a majority of the aggregate
principal amount of the outstanding Notes, subject to certain exceptions as
provided in the Indenture, on behalf of the Holders of all such Notes at a
meeting duly called and held as provided in the Indenture, to make, give or
take any request, demand, authorization, direction, notice, consent, waiver or
other action provided in the Indenture to be made, given or taken by the
Holders of the Notes, including without limitation, waiving (a) compliance
by the Company with certain provisions of the Indenture, and (b) certain
past defaults under the Indenture and their consequences.  Any resolution passed or decision taken at
any meeting of the Holders of the Notes in accordance with the provisions of
the Indenture shall be conclusive and binding upon such Holders and upon all
future Holders of this Note and other Notes issued upon the registration of
transfer hereof or in exchange heretofore or in lieu hereof.


10.           Persons
Deemed Owners.  The Company, the
Trustee, and any agent of the Company or the Trustee may deem and treat the
Person in whose name this Note is registered on the Security Register as its
absolute owner for all purposes.


11.           Authentication.  This Note shall not be valid until
authenticated by the manual signature of the Trustee or an authenticating
agent.



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12.           Governing
Law.  THE INTERNAL LAW OF THE
COMMONWEALTH OF MASSACHUSETTS SHALL GOVERN AND BE USED TO CONSTRUE THE
INDENTURE AND THE NOTES.


13.           No
Personal Liability.  THE THIRD
AMENDMENT AND RESTATEMENT OF DECLARATION OF TRUST OF THE COMPANY, AS AMENDED
AND SUPPLEMENTED, DATED JULY 1, 1994, A COPY OF WHICH, TOGETHER WITH ALL
AMENDMENTS AND SUPPLEMENTS THERETO (THE “DECLARATION”), IS DULY FILED IN THE
OFFICE OF THE DEPARTMENT OF ASSESSMENTS AND TAXATION OF THE STATE OF MARYLAND,
PROVIDES THAT THE NAME “HRPT PROPERTIES TRUST” REFERS TO THE TRUSTEES UNDER THE
DECLARATION COLLECTIVELY AS TRUSTEES, BUT NOT INDIVIDUALLY OR PERSONALLY, AND
THAT NO TRUSTEE, OFFICER, SHAREHOLDER, EMPLOYEE OR AGENT OF THE COMPANY SHALL
BE HELD TO ANY PERSONAL LIABILITY, JOINTLY OR SEVERALLY, FOR ANY OBLIGATION OF,
OR CLAIM AGAINST, THE COMPANY. ALL PERSONS DEALING WITH THE COMPANY, IN ANY
WAY, SHALL LOOK ONLY TO THE ASSETS OF THE COMPANY FOR THE PAYMENT OF ANY SUM OR
THE PERFORMANCE OF ANY OBLIGATION.


The Company will furnish to any Holder upon written
request and without charge a copy of the Indenture.  Request may be made to:


HRPT
Properties Trust


400
Centre Street


Newton,
MA 02458


Telecopier
No.:  (617) 332-2261


Attention: President


or such other address as
the Company may specify pursuant to the Indenture.



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ASSIGNMENT
FORM


To
assign this Note, fill in the form below:


[I] [We] assign and
transfer this Note to                                                                                                                                    
                                                                                                                 [Print or type assignee’s name, address and zip code]                                                                                                                  
[Insert assignee’s soc. sec. or tax I.D. no.]
and irrevocably appoint                                                                                           
to transfer this Note on the books of the Company.  The agent may substitute another to act for
him.


Date:


Your
Signature: 


[Sign exactly as your name appears on the face of this Note]


Signature Guarantee:


 


[The signature must be
guaranteed by


an officer of a participant in a recognized


signature guarantee program.  Notarized


or
witnessed signatures are not acceptable.]



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