Whenever under existing acts of Assembly of this Commonwealth any city or county has acquired, appropriated, or chosen, or shall acquire, appropriate, or choose a site for the erection of any public auditorium, library, memorial building, or monument, such city or county may agree with any other city or county with which under the provisions of this act it has the power jointly to erect such building, for the erection thereon of any such public auditorium, library, memorial building, or monument in accordance with the provisions of this act.
53 P.S. § 1344