Ключевые слова: abandoned, collector, communication, concrete, dark, dirty, district heating, drainage, draining, duct, ducting, ductwork, engineering, environment, exploration, gas, heat, heating duct, homeless, industrial, inside, interior, light, line, long, network, no people, old, perspective, pipe, pipeline, pipelines, pipes, round, rusty, service, sewage, sewer, subway, technical, tube, tubing, tunnel, tunneler, tunnels, underground, utility, wall, wastewater, water,