Upon establishing the authority, the county, wherein the authority is located, shall grant to the authority the right to use any space below the plot of ground used as a courthouse site and such portion of the surface of said plot not then used by the county for a courthouse located thereon. The city shall likewise grant to the authority the right to use the space below the surface of the streets abutting on said courthouse site including the street intersections connecting said streets. The governing bodies of the county and city shall have authority to execute the required grants without a vote of the electorate or any authorization other than that contained in sections 14-1701 to 14-1725. All such grants shall be for a period of fifty years. The authority may also acquire by lease, purchase, gift, grant, or any lawful manner, such adjoining privately owned property as may be necessary or convenient for the exercise of its powers for the construction of entrances to or exits from its parking facilities.