Whenever any public building belongs to or is used by a county and is situate on land dedicated to public use but which is not owned by the county in fee, the board may select and acquire a new site for the building and erect a new building or remodel an existing building on the new site for the purpose. To this end the board and the holders of title to the land and any other person or public, private, or municipal corporation having an interest therein, may sell the land upon such terms and conditions as are agreed upon by the respective parties, and may abandon or convey their several interests and abandon the interest of the public in the land.