That in such manner and under such limitations as may be provided by law, the state, or any county or city may acquire by eminent domain such property, or rights in property, in excess of that actually to be occupied by the public improvement or used in connection therewith, as may be reasonably necessary to effectuate the purposes intended, and may be vested with the fee simple title thereto, or the control of the use thereof, and may sell such excess property with such restrictions as shall be appropriate to preserve the improvements made.