Height limitations stipulated elsewhere in this chapter shall not apply to church spires, belfries, cupolas and domes, monuments, flagpoles, fire towers, water towers or masts or to necessary mechanical appurtenances or to parapet walls, except that no parapet wall may extend more than four feet above the limiting height of the building, or to farm silos, provided that the silo is located no less than 100 feet from any lot line. See subsection 40-8.3 for Antennas.