Postojna Cave is with its 24 km of passages, galleries and chambers, the largest cave in the “classic karst” and the longest publicly accessible depth of any cave system in the world. The cave was first described in the 17th century. The symbol of Postojna Cave is the stalagmite named Brilliant. It is also home to the endemic olm, the largest troglodyte amphibian in the world. The most visited tourist cave in Europe (more than 38 million visitors) represents an outstanding underground world, where the geological past is recorded in a unique manner. In 2018 Postojna Cave is celebrating its 200th anniversary.