Exhibit 4.2.1

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CONFORMED
  COPY



LAFARGE (U.S.) HOLDINGS

FIRST AMENDMENT TO THE AGREEMENT AND ARTICLES OF TRUST

DATED
  AS OF May 23, 2003



|PADOCS01/227720.2 | Lafarge
      (US) HoldingsFirst Amendment to Trust Agreement | Conformed
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1

AMENDMENT
  NUMBER 1 TO THE AGREEMENT AND ARTICLES OF TRUST (thisAmendment)
  made, delivered and accepted as of this 23rd day of May 2003, among
  Lafarge S.A. (Lafarge or the Settlor),
  a French société anonyme, and Alfred J. Ross of New York, New
  York, John H.F. Haskell, Jr. of New York, The Bank of New York, a New York
  banking corporation, as trustees (such individuals and corporations and their
  successors as trustees are herein, the Trustees). WHEREAS Lafarge
    and the Trustees entered into an agreement and articles of trust dated as
    of August 1, 2000 (the Trust Agreement; capitalized terms
    used herein and not defined herein shall have the meanings ascribed thereto
    in the Trust Agreement), which provided for the creation of Lafarge (U.S.)
    Holdings (U.S. Holdings or the Trust)
    and the transfer to U.S. Holdings of shares in Lafarge North America, a corporation
    organized under the laws of Maryland (U.S. Corp.) held
  by Lafarge; WHEREAS Lafarge
    intended that the terms of the Trust Agreement would provide an inducement
    for a person making a tender offer or exchange offer for Lafarges shares
  to make a comparable tender offer for U.S. Corp.s public shares; WHEREAS Section
    1.5(d) of the Trust Agreement provides that prior to a Commencement Date
    Lafarge may amend the Trust Agreement; provided, however, that any amendment
    to the Trust Agreement which alters the powers, duties, liabilities or rights
    to indemnification of the Trustees may only be made with the consent of the
    Trustees and that no amendment is permitted which (i) materially adversely
    affects the intent, purposes or effectiveness of Article VI of the Trust
    Agreement or (ii) affects Section 1.5 of the Trust Agreement, except an amendment
    which further restricts Lafarges ability under the Trust Agreement
  to withdraw or transfer the whole or any part of the Trust corpus; WHEREAS Section
    6.4(g) of the Trust Agreement provides that during a period other than an
    Operative Period or a Five Year Period the Settlor and the Trustees may by
    mutual consent declare that the Trust be construed, regulated and governed
  by the laws of any country or subdivision thereof; WHEREAS No
    Operative Period or Five Year Period has begun and this Amendment is made
  prior to a Commencement Date; WHEREAS Pursuant
    to Section 1.5(d) of the Trust Agreement and for the benefit of the beneficiaries
    of the Trust, Lafarge and the Trustees wish to enter into this Amendment
    in order to clarify the beneficial interests created by the Trust and to
    provide that the situs of the Trust will be Maryland and that the Trust Agreement
  shall be governed by Maryland law. NOW, THEREFORE,
  the parties hereto agree as follows: 1.Amendment to
  the Recitals.
  Pursuant to and in accordance with Section1.5(d)
  of the Trust Agreement, the second paragraph of the recitals to the Trust Agreement
  is amended by:


|PADOCS01/227720.2 | Lafarge
      (US) Holdings 
      First Amendment to Trust Agreement | Conformed
      Copy
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2

(a) adding
    a new sub-paragraph (ii) which shall read in its entirety as follows:


 (ii)
      to extend to U.S. Corp. and LCI, Swiss Corp. and Venezuelan Corp., for
      a period of ten years from the date hereof, in the event of a tender or
      exchange offer under French law for Lafarges shares, (A) an assurance
      that the strategy and policies of U.S. Corp., and LCI , Swiss Corp. and
      Venezuelan Corp. will not be substantially modified as a result of a successful
      tender offer or exchange offer for Lafarges shares and (B) an opportunity
      to protect the interests of all of the equity holders of U.S. Corp. and
      LCI, Swiss Corp. and Venezuelan Corp. and


(b) renumbering
    sub-paragraphs (ii) through (vi) so that they shall now be sub-paragraphs
    (iii) through (vii) respectively. (c) amending
  and restating in its entirety the third paragraph of the recitals to the Trust
  Agreement as follows:


WHEREAS
    the Settlor requests and the Board accepts the Settlors request to hold
    the Shares for the benefit of the Settlor and U.S. Corp. as the beneficiairies
    of the Trust and as hereinafter set forth. 2.Amendment
    to SECTION 1.8.
    Pursuant to and in accordance with Section1.5(d)
    of the Trust Agreement, Section 1.8 of the Trust Agreement is amended and
    restated in its entirety as follows: SECTION
    1.8 Governing Law; Exclusive Jurisdiction. (a)Governing
    Law. This
    Trust Agreement, the Trust created hereunder and any cause of action arising
    out of or related to this Trust Agreement or the Trust shall be governed by,
    and construed under, the laws of the State of Maryland applicable to contracts
    and instruments in and to be performed entirely in such State. (b)Exclusive
    Jurisdiction.
    All litigation with respect to any claims, disputes or causes of action arising
    out of or related to this Trust Agreement or the Trust shall be commenced
    exclusively in the Federal courts of the United States located in New York
    County in the State of New York, or, if such courts do not accept jurisdiction,
    in the Supreme Court of the State of New York, New York County.


3.Amendment
    to SECTION 6.2.
    Pursuant to and in accordance with Section1.5(d)
    of the Trust Agreement, Section 6.2 of the Trust Agreement is amended and
    restated in its entirety as follows: SECTION
    6.2Statement
    of Intent.It
    is the intent of the Settlor:


(i)  to
    extend to the public shareholders of U.S. Corp. and LCI, for a period of
    ten years from the date hereof, in the event of a tender or exchange offer
    under French law for Lafarges shares:


|PADOCS01/227720.2 | Lafarge
      (US) Holdings  
        First Amendment to Trust Agreement | Conformed
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3

(A)an
    opportunity, comparable to that presently enjoyed under French law and regulations
    by public shareholders ofFrench subsidiaries of French corporations, to receive a tender offer for
    their shares, or alternatively, (B)
    an
    assurance that the strategy and policies of U.S. Corp. will not be substantially
    modified as a result of a successful tender or exchange offer for Lafarges
    shares;


if
  at such time Lafarge's Beneficial Ownership of Voting Shares of U.S. Corp. comprises
  20% or more of the voting power represented by the outstanding Voting Shares
  of U.S. Corp. (assuming that at such time Lafarges 20% or more Beneficial
  Ownership of Voting Shares of such corporation is greater than the Beneficial
  Ownership of Voting Shares of such corporation owned by any other Person);

(ii)
    to extend
    to U.S. Corp. for a period of ten years from the date hereof, in the event
    of a tender or exchange offer under French law for Lafarges shares,
    (i) an assurance that the strategy and policies of U.S. Corp. will not be
    substantially modified as a result of a successful tender or exchange offer
    for Lafarges shares and (ii) an opportunity to protect the interests
    of all equity holders; (iii)to
      provide in this Trust Agreement inducements for a person making a tender
      or exchange offer for Lafarge's shares to make the U.S. Tender Offer, failing
    which Lafarge shall make such U.S. Tender Offer; and (iv)to
      provide in this Trust Agreement, if the U.S. Tender Offer is not made and
      consummated, for a five-year exercise by the Trustees, for the protection
      of the public equity holders of U.S. Corp. and LCI, of the voting rights
      with respect to the U.S. Corp. securities held in the Trust on the terms
    and conditions herein provided.


It is the
      further intent of the Settlor to benefit U.S. Corp. by making it a beneficiary
      of the Trust to the extent that the provisions of the Trust provide U.S.
      Corp. (i) with the right to direct
      the voting of the Shares as set forth in Section 6.4 (a)(ii) and (ii) with
      an opportunity to (x) ensure that the strategy and policies of U.S. Corp.
      will not be substantially modified as a result of a successful tender or
      exchange offer for Lafarges shares and (y) take the action necessary
      or desirable to protect the interests of all equity holders of U.S. Corp. The
    primary purpose of this Article VI is (x) to provide a mechanism for the commencement
    and termination of an Operative Periodor
    a Five-year Period and(y)
    to set forth thepowers
    and duties of the Trustees
    in connection with and during an Operative Period or a Five-year Period. To
    the extent that there is any conflict between this Article VI and any other
    Article of this Trust Agreement, as amended, the provisions of this Article
    VI shall prevail.


|PADOCS01/227720.2 | Lafarge
      (US) Holdings 
         First Amendment to Trust Agreement | Conformed
      Copy
|----------------- | ------------------------------------------------------------------------ | --------------------

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4

4.Change
    of Situs.
    (a) Pursuant to Section 6.4(g) of the Trust Agreement and in order to effectuate
    the purpose and intent of, and in compliance with, the Trust, the Trustees
    and the Settlor hereby agree and declare that the Trust and the Trust Agreement
    shall from the date hereof be governed, construed and regulated by the laws
    of the State of Maryland. (b) The
    Trustees as defined herein shall continue as Trustees of the Trust. 5. Headings.
    The section headings herein are for convenience of reference only, do not
    constitute part of this Amendment, and shall not be deemed to limit or otherwise
    affect any of the provisions hereof. 6.Effective
    Date. This
    Amendment shall be effective only upon execution by the Settlor and all Trustees. 7.Counterparts.
    This Amendment may be executed in one or more counterparts, and by the different
    parties hereto in separate counterparts, each of which when executed shall
    be deemed to be an original, but all of which taken together shall constitute
    one and the same instrument. 8.Force
    and Effect.
    Except to the extent amended by this Amendment, the Trust Agreement shall
    remain in full force and effect.


|PADOCS01/227720.2 | Lafarge
      (US) Holdings  
        First Amendment to Trust Agreement | Conformed
      Copy
|----------------- | ------------------------------------------------------------------------ | --------------------

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5

IN WITNESS
  WHEREOF, the undersigned have hereunto set their hands and agree to be bound
  by the terms of this Amendment as of May 23, 2003.


| |                         
| | ------------------------
| |                         
| | LAFARGE                 
| |                         
| | By                      
| | Name                    
| | Title                   
| |                         
| |                         
| |                         
| | /s/
      Alfred J. Ross
| | Trustee                 
| |                         



|PADOCS01/227720.2 | Lafarge
      (US) Holdings 
         First Amendment to Trust Agreement | Conformed
      Copy
|----------------- | ------------------------------------------------------------------------ | --------------------

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