For the purpose of defraying the cost of acquiring the buildings, land and appurtenances thereto by purchase, construction or extension, any county of the first class may borrow money and issue negotiable bonds, except that no bonds shall be issued unless and until authorized by an ordinance or order of the governing body of the county specifying the proposed undertaking, the amount of bonds to be issued and the maximum rate of interest the bonds are to bear. The ordinance or order shall further provide that the proposed land, building or buildings and appurtenances which are to be acquired, are to be acquired or built pursuant to the provisions of sections 49.520 to 49.580.