Tour description provided by Viator

On this day we take you to the biggest and worldwide known Slovenian cave system - the Postojna caves. A two million years old and 21 km long system of subterranean caves is one of the most easily accessible network of underground caves in the world. A ride by electrical train will be followed by a guided walk through a series of cave halls with drop stones, pillars and translucent curtains that create unforgettable impressions. The underworld system is a home of the mysterious, unique and rare amphibian Proteus Anguinus, or human fish as it is popularly called here.

Only 9 km away stands one of the most interesting baroque castles of Slovenia, the Predjama castle. It hangs dramatically in the middle of 123 m high rocky cliff.