Postojna Cave is the world's second-longest tourist cave system and Europe's most visited, spanning over 24 kilometers of stunning passages and chambers. The unique tour begins with a ride on a historic electric train operating since 1872, taking you through 3.7 kilometers of spectacular rock formations before an hour-long guided walk. The most famous landmark is the 5-meter gleaming white stalagmite called 'Brilliant'. The cave is home to the legendary proteus or 'human fish' — a blind amphibian that lives up to 100 years and can be seen in the Vivarium Proteus exhibit. The constant 10°C temperature requires warm clothing year-round.