Church spires, domes, flagpoles, antennas, windmills, chimneys, cooling towers, elevator bulkheads, fire towers, belfries, monuments, stacks, derricks, conveyors, stage towers or scenery lofts, tanks, water towers, silos, or necessary mechanical appurtenances, may be erected to any lawful and safe height. Cellular, or wireless communications systems are not subject to this exception and shall be regulated according to Section