The Postojna Cave
is a system of 20 kilometres of passages, galleries, and chambers, which have been visited by over 33 million visitors
accompanied by experienced guides over almost two hundred years. At the same time it is the largest Classical Karst cave and the most visited cave in Europe. Already in 1872, railway tracks were installed in the cave, and in 1884, electricity was also installed. Today, visitors can satisfy their curiosity by learning about the origin of the caves, by examining the passages and chambers, and especially by observing the rising stalagmites or hanging stalactites, the joining columns, the creasing curtains, and the strings of endless fantastic shapes. The cave is easily accessible
and has no steps or steep inclines; part of the cave is viewed from the train, and the rest can be observed on foot. The Postojna Cave is also considered the birthplace of speleobiology. The Postojna-Planina cave system is the home of as many as 85 completely adapted animal species
, making it the world’s largest cave ecosystem, and the crown jewel of biological diversity. The most famous inhabitant is of course the olm, or the human fish (Proteus anguinus).