For the purpose of preserving for the benefit of the American people as a national historical park certain historical structures and properties of outstanding national significance located in Philadelphia, Pennsylvania, and associated with the American Revolution and the founding and growth of the United States, the Secretary of the Interior, following the consummation of agreements with the city of Philadelphia and the Carpenters’ Company of Philadelphia as prescribed in section
407n of this title, is authorized to acquire by donation or with donated funds, or to acquire by purchase, any property, real or personal, within the following-described areas, such park to be fully established as the “Independence National Historical Park” when, in the opinion of the Secretary, title to sufficient of the lands and interests in lands within such areas, shall be vested in the United States: Provided, That the park shall not be established until title to the First United States Bank property, the Merchants’ Exchange property, the Bishop White house, the Dilworth-Todd-Moylan house, and the site of the Benjamin Franklin house, together with two-thirds of the remaining lands and interests in lands within the following-described areas, shall have been vested in the United States: