11. See a concert at Postojna Cave
Europe’s most visited cave, and probably your first choice for a cave tour, is near the town of Postojna, southwest of Ljubljana. Postojna Cave comprises 20km (13 miles) of halls and passages, of which a quarter is open to the public. The 90-minute tour starts with a train ride through ingeniously lit tunnels and grottoes dripping with stalactites and stalagmites.
Here one can also visit the Concert Hall, which can hold audiences of up to 10,000 and is occasionally used for concerts.
The Speleobiological Station close to the cave entrance shows a short film about the karst, and displays live specimens of cave fauna. It is amazing to think that anything at all can live in these conditions.