Existing structures. By way of illustration, existing structures, as referred to in these regulations governing the siting of commercial mobile service facilities, shall include but not be limited to signs, church spires, belfries, cupolas, domes, monuments, water towers, preexisting tower structures, windmills, chimneys, smokestacks, buildings, utility towers, clock towers, silos, barns or other agricultural buildings, steeples, radio or television towers and commercial parking lot light poles.