EXHIBIT 4.1

                      FORM OF SUPPLEMENTAL INDENTURE NO. 8

                                 by and between

                              HRPT PROPERTIES TRUST

                                       and

                       STATE STREET BANK AND TRUST COMPANY

                               as of July 31, 2000


             SUPPLEMENTAL TO THE INDENTURE DATED AS OF JULY 9, 1997



                      ------------------------------------



                              HRPT PROPERTIES TRUST
                          8.875% Senior Notes due 2010

<PAGE>

         This SUPPLEMENTAL INDENTURE NO. 8 (this "Supplemental  Indenture") made
and entered into as of July 31, 2000 between HRPT  PROPERTIES  TRUST, a Maryland
real estate  investment trust (the  "Company"),  and STATE STREET BANK AND TRUST
COMPANY, a Massachusetts trust company, as Trustee (the "Trustee"),

                                WITNESSETH THAT:

         WHEREAS,  the Company and the Trustee have  executed  and  delivered 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; and

         WHEREAS,  the Company has determined to issue debt securities  known as
its 8.875% Senior Notes due 2010; 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 (i)  existing at the time such
Person becomes a Subsidiary or (ii) assumed in connection  with the  acquisition
of assets from such Person, in each case, other than Debt incurred in connection
with,  or in  contemplation  of,  such  Person  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 the date the acquired  Person
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.
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                                      -2-


         "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.

         "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 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 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.
<PAGE>
                                      -3-


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

         "Make-Whole  Amount" means, in connection with any optional  redemption
or accelerated  payment of any Notes,  the excess,  if any, of (i) the aggregate
present value as of the date of such  redemption or accelerated  payment of each
dollar of principal being redeemed or paid and the amount of interest (exclusive
of interest accrued to the date of redemption or accelerated payment) that would
have been payable in respect of such dollar if such  redemption  or  accelerated
payment had not been made,  determined by  discounting,  on a semiannual  basis,
such principal and interest at the  Reinvestment  Rate  (determined on the third
Business  Day  preceding  the  date  such  notice  of  redemption  is  given  or
declaration of  acceleration  is made) from the  respective  dates on which such
principal and interest would have been payable if such redemption or accelerated
payment had not been made, over (ii) the aggregate principal amount of the Notes
being  redeemed or paid.  For purposes of this  Supplemental  Indenture  and the
Notes, references in the Indenture to the payment of the principal (and premium,
if any) and  interest on the Notes shall be deemed to include the payment of the
Make-Whole  Amount,  if any, due upon redemption with respect to the Notes.  The
Make-Whole  Amount  shall  be  calculated  by the  Company  and set  forth in an
Officer's  Certificate  delivered  to the  Trustee,  and the  Trustee  shall  be
entitled to rely on said Officer's Certificate.

         "Notes" means the Company's 8.875% Senior Notes due 2010,  issued under
this Supplemental  Indenture and the Indenture,  as amended or supplemented from
time to time.

         "Reinvestment  Rate"  means a rate per annum  equal to the sum of 0.50%
(fifty  one-hundredths of one percent) plus the yield on treasury  securities at
constant  maturity under the heading "Week Ending"  published in the Statistical
Release  under the  caption  "Treasury  Constant  Maturities"  for the  maturity
(rounded to the nearest month)  corresponding to the remaining life to maturity,
as of the payment date of the principal  being  redeemed or paid. If no maturity
exactly  corresponds to such maturity,  yields for the two published  maturities
most closely  corresponding to such maturity shall be calculated pursuant to the
immediately  preceding  sentence and the Reinvestment Rate shall be interpolated
or extrapolated from such yields on a straight-line  basis,  rounding in each of
such relevant  periods to the nearest  month.  For purposes of  calculating  the
Reinvestment  Rate, the most recent  Statistical  Release published prior to the
date of determination of the Make-Whole Amount shall be used.

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

         "Statistical   Release"  means  the  statistical   release   designated
"H.15(519)"  or any  successor  publication  which is  published  weekly  by the
Federal  Reserve System and which  establishes  yields on actively traded United
States  government  securities  adjusted  to  constant  maturities  or,  if such
statistical release is not published at the time of any determination under this
Supplemental  Indenture,  then any publicly  available  source of similar market
data which shall be designated by the Company.

          "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 of which 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
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                                      -4-


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.

         "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
"8.875%  Senior  Notes due 2010."  The Notes  will be  limited  to an  aggregate
principal  amount of $30,000,000,  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  and 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
<PAGE>
                                      -5-


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 and Interest  Rate. The Notes will bear interest at a rate
of 8.875% per annum,  from July 31, 2000 (or,  in the case of Notes  issued upon
the reopening of this series of Notes,  from the date  designated by the Company
in connection with such reopening) or from the  immediately  preceding  Interest
Payment  Date to which  interest  has been paid or duly  provided  for,  payable
semiannually on each February 1 and August 1, commencing  February 1, 2001 (each
of which shall be an "Interest Payment Date"), to the Persons in whose names the
Notes are  registered  in the Security  Register at the close of business on the
day falling 14 calendar days (whether or not a Business Day) next preceding such
Interest Payment Date (each, a "Regular Record Date").

         (c) Principal Repayment;  Currency. The stated maturity of the Notes is
August 1, 2010,  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,  located
initially at Two Avenue de Lafayette,  Boston, Massachusetts 02111, 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 at any time 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 (i) the principal  amount of the Notes being redeemed,
plus accrued and unpaid  interest to but  excluding  the  applicable  Redemption
Date,  plus (ii) the Make-Whole  Amount.  Upon the  acceleration of the Notes in
accordance with Section 502 of the Indenture, the principal amount of the Notes,
plus accrued and unpaid interest thereon and the Make-Whole  Amount shall become
due and payable immediately.

         (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,  Massachusetts 02458, Attention:  President;
notices to the  Trustee  shall be  directed  to it at Two  Avenue de  Lafayette,
Boston,  Massachusetts 02111,  Attention:  Corporate Trust Department,  Re: HRPT
Properties  Trust 8.875 % Senior Notes due 2010; or as to either party,  at such
other address as shall be  designated  by such party in a written  notice to the
other party.
<PAGE>
                                      -6-


         (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 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
<PAGE>
                                      -7-


         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 maintain at all times Total  Unencumbered  Assets of not less
than 200% of the aggregate outstanding principal amount of the Unsecured Debt of
the Company and its Subsidiaries on a consolidated basis.


                                    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
<PAGE>
                                      -8-


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 outstanding of at least $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.

         Section  4.2.  Notwithstanding  any  provisions  to the contrary in the
Indenture,  upon  any  acceleration  of  the  Notes  under  Section  502  of the
Indenture,  the amount immediately due and payable in respect of the Notes shall
equal the Outstanding principal amount thereof, plus accrued interest,  plus the
Make-Whole Amount.

                                    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
counterparts,  each  of  which  shall  be an  original  and all of  which  shall
constitute but one and the same instrument.
<PAGE>
                                      -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:___________________________
                                                  Name:
                                                  Title:


                                            STATE STREET BANK AND TRUST COMPANY,
                                            as Trustee


                                            By:___________________________
                                                  Name:
                                                  Title:



<PAGE>
                                                                       EXHIBIT A

                                  FORM OF NOTE

                                 [Face of Note]

                           8.875% Senior Note due 2010

No. ______                                                         $_________

                              HRPT PROPERTIES TRUST

promises to pay to ______________________________________ or registered assigns,
the  principal sum of  _____________________________________  on August 1, 2010,
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 February 1 and August 1,  commencing  February 1,
2001.

Record  Dates:  the day falling 14 calendar  days prior to any Interest  Payment
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:

                                        STATE STREET BANK AND TRUST COMPANY,
                                        as Trustee


                                        By:_______________________________
                                           Authorized Officer

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<PAGE>
             [THE FOLLOWING CONSTITUTES THE REVERSE OF THE SECURITY]

                              HRPT PROPERTIES TRUST

                           8.875% Senior Note due 2010

         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.

         The Company shall pay in cash interest on the principal  amount of this
Note  at  the  rate  per  annum  of  8.875%.   The  Company  will  pay  interest
semi-annually in arrears on each February 1 and August 1, commencing on February
1,  2001,  or,  if any  such  day is  not a  Business  Day  (as  defined  in the
Indenture),  on the next  succeeding  Business  Day (each an  "Interest  Payment
Date"),  to Holders of record on the day  falling 14 calendar  days  immediately
preceding such Interest Payment Date (whether or not a Business Day).

         Interest will be computed on the basis of a 360-day year  consisting of
twelve 30-day  months.  Interest shall accrue from the most recent date to which
interest has been paid or, if no interest has been paid, from July 31, 2000.

         2.  Method of  Payment.  The  Company  will pay  interest  on the Notes
(except defaulted  interest) to the Persons who are registered  Holders of Notes
at the close of business on the record date next preceding the Interest  Payment
Date,  even if such Notes are  canceled  after such record date and on or before
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. 8 thereto,  dated as of July
31, 2000 (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  limited  to  $30,000,000  in  aggregate  principal  amount,  except  as
otherwise provided in the Indenture.

         4. Optional Redemption.  The Notes will be subject to redemption at any
time at the option of the  Company,  in whole or in part,  upon not less than 30
nor more than 60 days' notice, at a redemption price equal to the sum of (i) the
principal  amount of the Notes being redeemed,  plus accrued and unpaid interest
to but excluding the applicable Redemption Date and (ii) the Make-Whole Amount.

                                      A-2
<PAGE>

         As used herein the term  "Make-Whole  Amount" means, in connection with
any optional redemption or accelerated payment of any Notes, the excess, if any,
of (i)  the  aggregate  present  value  as of the  date of  such  redemption  or
accelerated  payment of each dollar of principal  being redeemed or paid and the
amount of interest  (exclusive of interest  accrued to the date of redemption or
accelerated  payment)  that would have been payable in respect of such dollar if
such  redemption  or  accelerated  payment  had not  been  made,  determined  by
discounting,  on  a  semiannual  basis,  such  principal  and  interest  at  the
Reinvestment  Rate (as defined  herein)  (determined  on the third  Business Day
preceding  the date  such  notice  of  redemption  is given  or  declaration  of
acceleration  is made) from the  respective  dates on which such  principal  and
interest would have been payable if such  redemption or accelerated  payment had
not been  made,  over (ii) the  aggregate  principal  amount of the Notes  being
redeemed or paid.

         As used  herein  the term  "Reinvestment  Rate"  means a rate per annum
equal to the sum of 0.50% (fifty  one-hundredths  of one percent) plus the yield
on treasury  securities  at constant  maturity  under the heading  "Week Ending"
published  in the  Statistical  Release  (as defined  herein)  under the caption
"Treasury  Constant  Maturities" for the maturity (rounded to the nearest month)
corresponding  to the remaining life to maturity,  as of the payment date of the
principal  being  redeemed or paid. If no maturity  exactly  corresponds to such
maturity,  yields for the two published maturities most closely corresponding to
such maturity shall be calculated pursuant to the immediately preceding sentence
and the Reinvestment Rate shall be interpolated or extrapolated from such yields
on a  straight-line  basis,  rounding  in each of such  relevant  periods to the
nearest  month.  For purposes of  calculating  the  Reinvestment  Rate, the most
recent  Statistical  Release published prior to the date of determination of the
Make-Whole Amount shall be used.

         As used herein the term  "Statistical  Release"  means the  statistical
release designated  "H.15(519)" or any successor  publication which is published
weekly by the Federal  Reserve System and which  establishes  yields on actively
traded United States government  securities  adjusted to constant maturities or,
if such  statistical  release is not published at the time of any  determination
under the Supplemental Indenture,  then any publicly available source of similar
market data which shall be designated by the Company.

         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


                                      A-3
<PAGE>

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.

         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 AMENDED AND  RESTATED  DECLARATION  OF
TRUST OF THE  COMPANY,  DATED JULY 1, 1994, A COPY OF WHICH,  TOGETHER  WITH ALL
AMENDMENTS  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.

                                      A-4
<PAGE>



                                 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.]