Ключевые слова: abandoned, background, catacomb, cave, cavern, cellar, coal, construction, copper, corridor, dark, deep, dig, dirt, dirty, dungeon, dust, entrance, excavate, facility, geology, hole, industrial, industry, inside, interior, iron, light, long, material, mine, mineral, mining, narrow, old, passage, primary, rail, railroad, railway, resource, rock, secret, shaft, spooky, structure, tunnel, underground, work,