Ключевые слова: abandoned, bright, cable, cable tunnel, collector, communication, connect, connection, construction, dark, dirty, district heating, electric, electrical, electricity, engineering, environment, extremal tourism, heat, heating duct, illuminated, industrial, industry, interior, led flashlight, light, line, modern, network, no people, perspective, pipe, pipeline, pipelines, sewer, station, subway, technical, technology, transport, transportation, tube, tunnel, ukraine, underground, underground communication, urban, utility, utility tunnel, wiring,