The board of supervisors of any county in the state is hereby empowered, in its discretion, to acquire by gift, donation or purchase necessary real estate on which to erect, construct or reconstruct public health buildings and clinics sponsored by the public health units of any county, or a public health building to house the county health department, said funds to be expended out of the general fund or out of any fund collected from a special levy made by said county for public health purposes. In said construction the board of supervisors of all counties are hereby empowered to erect said buildings in conjunction with any municipality situated in any county or in conjunction with any federal agency, and the board of supervisors is hereby authorized to sponsor any of such said projects, or, in the discretion of said board, said buildings may be constructed under contract after advertising as provided by law and upon competitive bids received therefor.