The county commissioners of such counties and the corporate authorities of such cities shall have the power and they are hereby authorized to agree upon a site within the limits of such cities and counties, and to acquire, own, and hold the same as tenants in common, and to erect thereon jointly public auditoriums, libraries, memorial buildings, or monuments. The county commissioners of such counties and the corporate authorities of such cities shall have full authority to erect upon the land thus obtained and held, the building or buildings agreed upon as hereinafter provided.
53 P.S. § 1342