53 Pa. Stat. § 1331
In each county of this Commonwealth, where the county-seat is within the limits of any city, the county commissioners and the proper corporate authorities of such city shall have the power and they are hereby authorized, to agree upon a site within the limits of such city, and to erect thereon a joint county and municipal building, to be used by the county for court house and other purposes, and to be used by the city for municipal purposes.
The land upon which said building shall be erected shall be owned in severalty by such county and city; and the part of such building which shall stand upon the land owned in severalty by the county shall belong in severalty to the county, and the part of such building which shall stand upon the land owned in severalty by the city shall belong in severalty to the city. The county commissioners of such county and the corporate authorities of such city shall choose such site, and shall determine the parts of the land so chosen which shall be owned in severalty by each; and when this has been done, and the erection of such joint building has been agreed upon, they shall agree upon and adopt plans for such joint building. The building may be so designed and constructed that part of the building on the land owned by each shall be used by each, respectively; or, the building may be so designed and constructed as to permit of the use by the county of any portion or portions of the part of the building owned by the city, and likewise to permit of the use by the city of any portion or portions of the part of the building owned by the county; and, whether so specially designed or not, the county commissioners and corporate authorities of such city shall have the power, and they are hereby authorized, to permit of the use by the county of any portion or portions of the part of the building owned by the city, and likewise to permit of the use by the city of any portion or portions of the part of the building owned by the county, upon such terms and conditions as may be in the judgment of the county commissioners and the corporate authorities just and reasonable. The building shall be so constructed as to permit of an apportionment of the cost of the part thereof owned respectively by such county and city, and the building shall be paid for in accordance with such apportionment.
The county commissioners of such county and the corporate authorities of such city may provide that the corridors, stairways, and elevators be used in common by both county and city. They may install for the whole building a single system of lighting, heat, ventilation, and plumbing, and for other general equipment, which shall be used in common by the county and the city. They may provide that the mechanical plants and power plants necessary for the elevators, lighting, heating, ventilating, plumbing, and cleaning, and the plants necessary for all other general equipment, be located partly in a portion of the part of the building owned by each, or that such plants or general equipment be located wholly in the part of the building owned by the county, or wholly in the part of the building owned by the city, in such a manner as to conveniently serve all portions of the building; and such plants or general equipment shall be considered and regarded as fixtures for the use and benefit of the whole building, and shall be paid for by the county and city in such equitable proportions as the county commissioners and proper executive officers of such city shall agree upon. If, however, the county commissioners and the corporate authorities of such city do not deem it advisable to provide such plants, or any of them, they may secure light, heat, or power for said building in such manner as to them may seem most advantageous; and may for said purposes, either jointly or separately, acquire other land in the vicinity of the joint county and municipal building, and construct thereon, or on land belonging to either or both, jointly or separately, mechanical plants and power plants for the purpose of supplying light, heat, and power to said joint building. The same to be supplied at such terms and conditions as may be, in the judgment of the county commissioners and the corporate authorities, just and reasonable.
The administration, maintenance, control, and operation of such joint building shall be, and is hereby vested, in the county commissioners and the proper executive officers of such city; and they shall exercise the powers and rights in relation thereto in such manner as the county commissioners and the proper executive officers of such city may, from time to time, agree upon.
53 P.S. § 1331