The following types of structures or structural parts are not subject to the building height limitations of this chapter except in residentially-zoned areas unless otherwise restricted: chimneys, cupolas, tanks, church spires, belfries, domes, derricks, monuments, fire and hose towers, observation towers, transmission towers, smokestacks, flagpoles, radio and television towers, masts, aerials, cooling towers, water towers, elevator shafts, windmills, conveyors and other similar projections.