airports aqueducts architecture bridges broadcast towers buildings campuses colleges condominiums cooling towers dams draw bridge estates fences freeway interchanges freeway overpasses greenhouses hotels interchanges lighthouses marinas megalithic monuments microwave towers mobile homes nuclear plants observatories offices piers pylons power generating power lines prisons radar antennae reservoirs resorts roller coasters shopping malls smokestacks stadiums suspension bridge tepees tract houses train stations truss bridge universities windmills