The area bounded by Seventh Street, Constitution Avenue, Fourth Street, and North Mall Drive, Northwest, in the District of Columbia, is appropriated to the Smithsonian Institution as a site for a National Gallery of Art. The Smithsonian Institution is authorized to permit the A. W. Mellon Educational and Charitable Trust (hereinafter referred to as the donor) to construct on said site for the Smithsonian Institution a building to be designated the National Gallery of Art, and to remove any existing structure and landscape the grounds within said area. The adjoining area bounded by Fourth Street, Pennsylvania Avenue, Third Street, and North Mall Drive, Northwest, in the District of Columbia, is reserved as a site for future additions to the National Gallery of Art. The project shall be in accordance with plans and specifications approved by the Commission of Fine Arts.

The Trustees of the National Gallery of Art are authorized to construct within the area reserved as a site for future additions by the third sentence of section 71 of this title one or more buildings to serve as additions to the National Gallery of Art. The cost of constructing any such building shall be paid from trust funds administered by such Trustees. The plans and specifications for any such building shall be approved by the Commission of Fine Arts and the National Capital Planning Commission.

Any building constructed under authority of section 71a of this title shall, upon completion, be a part of the National Gallery of Art.

Upon completion of the National Gallery of Art, the board shall accept for the Smithsonian Institution as a gift from the donor a collection of works of art which shall be housed and exhibited in the National Gallery of Art.

The Secretary of the Treasury is authorized and directed to receive into the Treasury from time to time as a permanent loan by the Board of Trustees of the National Gallery of Art to the United States sums in cash of not to exceed $5,000,000 in the aggregate, and to pay interest on the principal amount of such loan at a rate which is the higher of the rate of 4 per centum per annum or a rate which is .25 percentage points less than a rate determined by the Secretary of the Treasury, taking into consideration the current average market yield on outstanding long-term marketable obligations of the United States, adjusted to the nearest one-eighth of 1 per centum, payable semiannually. Such interest is permanently appropriated for payment to the Board of Trustees of the National Gallery of Art.