A municipal corporation may contract for the purchase of and hold any land not exceeding in the. whole five acres, either in or out of the borough, and thereon, or on any land belonging to or held in trust for the Corporation, may build a town hall, council house, justices' room, with or without a police station and cells, or lock-ups, or a quarter and petty sessions-house, or an assize courthouse, with or without judges' lodgings, or a polling station, or any other building necessary or proper for any purpose of the borough.