Postojna Cave and the Vivarium
Postojna Cave is the most popular Slovenian tourist attraction. The cave’s first visitor was Ferdinand I, the heir to the Austrian throne, who toured it in 1819; since then, more than 38 million people have done the same. Given that approximately a million people visit Postojna Cave each year, the next round jubilee cannot be far away. The main attractions of the cave are its stunning formations, the train that takes visitors through the first part of the cave, and of course the proteus, a peculiar cave animal that can be viewed from up close at the Vivarium, along with the rest of the dwellers of the mystical underground.