Ключевые слова: ancient, archeology, awe, beautiful, cave, cavern, cliff, damp, dark, deep, europe, excursion, formation, geology, grotto, heritage, historic, icicle, illuminated, inside, interior, karst, karst formation, lamp, limestone, mineral, mystery, mystic, national, nature, old, paleolithic, pivka river, postojna, postojnskajama, research, rock, slovenia, speleology, stalactite, stalagmite, stone, subway, travel destinations, tunnel, twilight, underground, unesco, wet,