                                                                     Exhibit 5.1




                              SULLIVAN & WORCESTER LLP
                               ONE POST OFFICE SQUARE
                             BOSTON, MASSACHUSETTS 02109
                                   (617) 338-2800
                                FAX NO. 617-338-2880
     IN WASHINGTON, D.C.                                   IN NEW YORK CITY
     1666 K STREET, N.W.                                   565 FIFTH AVENUE
   WASHINGTON, D.C. 20006                              NEW YORK, NEW YORK 10017
       (202) 775-8190                                       (212) 486-8200
    FAX NO. 202-293-2275                                 FAX NO. 212-758-2151




                                                              March 8, 2002


Hospitality Properties Trust
400 Centre Street
Newton, Massachusetts 02458

         Re: Hospitality Properties Trust Registration Statement on Form S-3

Ladies and Gentlemen:

         In  connection  with the  registration  statement on Form S-3 under the
Securities  Act of 1933,  as  amended  (the  "Securities  Act")  of  Hospitality
Properties  Trust, a Maryland real estate investment trust (the "Company" or the
"Registrant"), you have requested our opinions set forth below.

         You have provided us with a copy of such registration statement,  which
you  propose  to  file  with  the  Securities  and  Exchange   Commission   (the
"Commission") on or about the date hereof. Such registration  statement contains
a form of  preliminary  prospectus  with  respect to the offer and sale of up to
$2,800,000,000  in aggregate amount of one or more series of (i) debt securities
of the Company (the "Debt  Securities"),  (ii)  preferred  shares of  beneficial
interest,  without par value,  of the Company (the  "Preferred  Shares"),  (iii)
depositary  shares  representing   fractional   interests  in  Preferred  Shares
("Depositary  Shares")  evidenced by depositary  receipts therefor  ("Depositary
Receipts"), (iv) common shares of beneficial interest, $.01 par value per share,
of the Company (the "Common  Shares"),  and (v) warrants to purchase one or more
classes  of  securities   registered  under  the  Registration   Statement  (the
"Warrants" and, together with the Debt Securities,  Preferred Shares, Depositary
Shares,  and  Common  Shares,  the  "Registered  Securities"),  in each case for
offering  from time to time, as set forth in the final  prospectus  that forms a
part of the Registration Statement, as defined below (the "Prospectus"),  and as
to be set forth in one or more final  supplements  to the  Prospectus  (each,  a
"Prospectus Supplement").

         As used in this  opinion,  the  term  "Registration  Statement"  means,
unless otherwise stated, such registration  statement,  as amended when declared
effective by the Commission (including any necessary  post-effective  amendments
thereto),  and the term  "Convertible  Registered  Securities"  means Registered
Securities which are convertible into, exchangeable for or exercisable for other
Registered Securities, and the term "Underlying Registered Securities" means any
Registered  Securities which are issuable upon conversion,  exchange or exercise
of Convertible Registered Securities.


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Hospitality Properties Trust
March 8, 2002
Page 2

         In  connection  with this  opinion,  we have examined and relied upon a
copy of the  Registration  Statement to be filed with the Commission on or about
the date hereof.  We have also  examined and relied upon  originals or copies of
such records,  agreements and  instruments of the  Registrant,  certificates  of
public  officials and of officers of the Registrant and such other documents and
records, and such matters of law, as we have deemed necessary as a basis for the
opinions hereinafter expressed. In making such examination,  we have assumed the
genuineness  of all  signatures,  the legal  capacity  of natural  persons,  the
authenticity of all documents submitted to us as originals and the conformity to
the  originals of all documents  submitted to us as copies,  which facts we have
not independently verified.

         We have necessarily  assumed in connection with the opinions  expressed
below that the terms and conditions of the Registered Securities and any related
indentures,  agreements and  instruments,  except to the extent described in the
Registration Statement and the form of preliminary prospectus contained therein,
as originally filed, will be, and that any related proceedings of the Registrant
conducted  after the date hereof will be conducted,  (i) in accordance  with all
applicable  laws  and the  Registrant's  charter  and  bylaws,  and  (ii) not in
conflict with any  contractual  or other  restrictions  which are binding on the
Registrant,  and that,  without  limiting the generality of the  foregoing,  any
agreements or instruments that are hereafter  required to be filed as an exhibit
to the Registration  Statement will be properly filed by an amendment thereto or
by the filing of a Form 8-K by the Company under the Securities  Exchange Act of
1934, as amended,  and properly  incorporated  by reference in the  Registration
Statement,  as permitted by the Securities Act and the rules and  regulations of
the Commission thereunder.

         To the  extent  that  the  obligations  of the  Registrant  under  each
Indenture, Warrant Agreement or Depositary Agreement (each as defined below) may
be  dependent  upon such  matters,  we have assumed for purposes of this opinion
that each  Indenture  Trustee,  Warrant  Agent and  Depositary  Trustee (each as
defined below) are duly organized,  validly  existing and in good standing under
the  laws of  their  respective  jurisdictions  of  organization,  and are  duly
qualified to engage in the  activities  contemplated  by, and have the requisite
organizational  and legal  power  and  authority  to  perform  their  respective
obligations under, each Indenture, Warrant Agreement and Depositary Agreement to
which  they  are  parties,  that  each  Indenture  Trustee,  Warrant  Agent  and
Depositary Trustee will be in compliance,  generally with respect to acting as a
trustee  or  agent  under  each  applicable  Indenture,   Warrant  Agreement  or
Depositary  Agreement,  with all applicable laws and regulations,  and that each
Indenture,  Warrant  Agreement,  and Depositary  Agreement will be the valid and
binding  agreements  of  each  party  thereto  (other  than,  in the  case of an
indenture  in the form  filed as  Exhibit  4.1,  4.2 or 4.3 to the  Registration
Statement, when appropriately completed, the Company),  enforceable against such
parties in accordance with their respective terms.

         We express no opinion herein as to the laws of any  jurisdiction  other
than the laws of The Commonwealth of Massachusetts and the State of New York and
the federal laws of the United  States of America,  and we express no opinion as
to state  securities or blue sky laws.  Insofar as this opinion involves matters
of Maryland law we have, with your  permission,  relied solely on the opinion of
Ballard Spahr Andrews & Ingersoll,  LLP dated March 8, 2002, a copy of which

<PAGE>

Hospitality Properties Trust
March 8, 2002
Page 3

we  understand  you are  filing  herewith  as  Exhibit  5.2 to the  Registration
Statement,  and our  opinion is subject to the  exceptions,  qualifications  and
limitations therein expressed.

         Our  opinions  set forth below with  respect to the validity or binding
effect of any  security or  obligation  are subject to (i)  limitations  arising
under applicable bankruptcy,  insolvency,  reorganization,  fraudulent transfer,
moratorium or other  similar laws  affecting  the  enforcement  generally of the
rights and  remedies of  creditors  and secured  parties or the  obligations  of
debtors,  (ii) general principles of equity (regardless of whether considered in
a proceeding at law or in equity), including, without limitation, the discretion
of any court of  competent  jurisdiction  in granting  specific  performance  or
injunctive or other equitable  relief,  and (iii) an implied duty on the part of
the  party  seeking  to  enforce  rights or  remedies  to take  action  and make
determinations on a reasonable basis and in good faith to the extent required by
applicable law.

         Based on and subject to the  foregoing,  we are of the opinion that, as
of the date hereof:

                  1. Each series of Debt  Securities  will be validly issued and
         binding obligations of the Company when (i) the Registration  Statement
         shall have become effective under the Securities Act and the indentures
         filed  as  Exhibit  4.1,  4.2  and 4.3 to the  Registration  Statement,
         including any necessary supplemental indenture, or any other indenture,
         including any necessary  supplemental  indenture  thereto,  filed as an
         exhibit  to the  Registration  Statement,  as  the  case  may  be  (the
         applicable indenture,  as so filed and supplemented,  the "Indenture"),
         shall have been  qualified  under the Trust  Indenture  Act of 1939, as
         amended,  and the Indenture shall have been duly  authorized,  executed
         and  delivered  by the  Company  and a trustee  named  thereunder  (the
         "Indenture Trustee"), (ii) a Prospectus Supplement with respect to such
         series of Debt  Securities  shall have been  filed with the  Commission
         pursuant  to Rule 424 under the  Securities  Act,  (iii) the  Company's
         Board of Trustees or a duly  authorized  committee  thereof  shall have
         duly  adopted  final   resolutions   (the  "Final  Debt   Resolutions")
         authorizing  the  issuance  and sale of such Debt  Securities,  each as
         contemplated  by  the  Registration  Statement,  the  Prospectus,   the
         applicable  Prospectus  Supplement  and the  Indenture,  and (iv)  such
         series of Debt  Securities  shall  have been (A) duly  executed  by the
         Company and  authenticated by the Indenture  Trustee as provided in the
         Indenture and the Final Debt  Resolutions and (B) duly delivered to the
         purchasers   thereof  against  payment  of  the  agreed   consideration
         therefor,  as provided in the Registration  Statement,  the Prospectus,
         the applicable Prospectus Supplement,  the Indenture and the Final Debt
         Resolutions.   If  such  Debt  Securities  are  Underlying   Registered
         Securities,  the opinion set forth in this  paragraph is subject to the
         further condition that the Convertible  Registered  Securities relating
         to such Debt Securities, at the time of the issuance thereof and of the
         conversion,  exchange or exercise  thereof,  are validly issued,  fully
         paid and  non-assessable  by the  Company  or are  validly  issued  and
         binding obligations of the Company, as applicable.

                  2. The Depositary  Shares will be validly  issued,  fully paid
         and  non-assessable by the Company and the Depositary  Receipts will be
         validly  issued  and will  entitle  the  holders  thereof to the rights
         specified therein and in the applicable Depositary Agreement,  when (i)
         the  related  Preferred  Shares have been duly  authorized  and validly


<PAGE>

Hospitality Properties Trust
March 8, 2002
Page 4

         issued,  fully paid and  non-assessable,  (ii) the  Company's  Board of
         Trustees or a duly authorized committee thereof shall have duly adopted
         resolutions (the "Final Depositary Shares  Resolutions")  approving one
         or more depositary  agreements,  including a form of Depositary Receipt
         set forth therein or related thereto (each, a "Depositary  Agreement"),
         relating to such Depositary Shares, between the Company and a financial
         institution  identified  therein as depositary  (each, a "Depositary"),
         (iii) the applicable Depositary Agreement shall have been duly executed
         and  delivered  by the  Company  and the  Depositary,  (iv) the related
         Preferred  Shares shall have been duly  deposited  with the  Depositary
         under  the  Depositary  Agreement,  and (v) the  applicable  Depositary
         Receipts shall have been duly executed by the Depositary as provided in
         the applicable  Depositary  Agreement and the Final  Depositary  Shares
         Resolutions  and  registered  and shall have been duly delivered to the
         purchasers   thereof  against  payment  of  the  agreed   consideration
         therefor,  as provided in the Registration  Statement,  the Prospectus,
         the  applicable  Prospectus   Supplement,   the  applicable  Depositary
         Agreement and the Final Depositary Shares Resolutions.

                  3. The Warrants will be validly issued and binding obligations
         of the Company when (i) the  Registration  Statement  shall have become
         effective under the Securities  Act, (ii) a Prospectus  Supplement with
         respect to such  Warrants  shall  have been  filed with the  Commission
         pursuant to Rule 424 under the Securities Act, (iii) the Warrants shall
         have been duly authorized by the Company, including by the due adoption
         by the  Company's  Board of  Trustees  or a duly  authorized  committee
         thereof  of  final   resolutions  (the  "Final  Warrant   Resolutions")
         authorizing  the issuance and sale of such Warrants as  contemplated by
         the   Registration   Statement,   the  Prospectus  and  the  applicable
         Prospectus  Supplement  and approving  one or more warrant  agreements,
         including a form of warrant set forth therein or related thereto (each,
         a "Warrant  Agreement"),  establishing the terms and conditions of such
         Warrants,  between the Company and a financial  institution  identified
         therein as warrant agent (each, a "Warrant Agent"), (iv) the applicable
         Warrant  Agreement  shall have been duly  executed and delivered by the
         Company and the Warrant  Agent,  and (v) such Warrants  shall have been
         duly executed by the Company and  authenticated by the Warrant Agent as
         provided in the  applicable  Warrant  Agreement  and the Final  Warrant
         Resolutions  and  registered  and shall have been duly delivered to the
         purchasers   thereof  against  payment  of  the  agreed   consideration
         therefor,  as provided in the Registration  Statement,  the Prospectus,
         the applicable Prospectus Supplement,  the applicable Warrant Agreement
         and the Final  Warrant  Resolutions.  If such  Warrants are  Underlying
         Registered  Securities,  the  opinion  set forth in this  paragraph  is
         subject  to the  further  condition  that  the  Convertible  Registered
         Securities  relating  to such  Warrants,  at the  time of the  issuance
         thereof  and of the  conversion,  exchange  or  exercise  thereof,  are
         validly  issued,  fully paid and  non-assessable  by the Company or are
         validly issued and binding obligations of the Company, as applicable.

         All of the  opinions  set  forth  herein  are  rendered  as of the date
hereof, and we assume no obligation to update such opinions to reflect any facts
or circumstances which may hereafter come to our attention or any changes in the
law which may hereafter occur.


<PAGE>

Hospitality Properties Trust
March 8, 2002
Page 5

         We hereby  consent to the  filing of this  opinion as an exhibit to the
Registration  Statement  and to the  reference  to our  firm  in the  Prospectus
forming a part of the Registration  Statement. In giving such consent, we do not
thereby  admit that we come  within the  category  of persons  whose  consent is
required  under Section 7 of the Act or under the rules and  regulations  of the
Commission promulgated thereunder.

                                                 Very truly yours,

                                                 /s/ Sullivan & Worcester LLP

                                                 SULLIVAN & WORCESTER LLP






