Whenever under the provisions of this act any city and county shall enter into an agreement for the acquisition through condemnation proceedings of property for the purpose of erecting thereon any public auditorium, library, memorial building, or monument, such property shall be acquired by such city and county in the proportion as may be designated by the said agreement between the said city and county under existing acts of Assembly empowering any city or county separately to acquire land for the purpose of erecting thereon public auditoriums, libraries, memorials, and monuments.
53 P.S. § 1345