Postojna

The Postojna Cave is Europe's largest system of karst caves open to the public, with 24km of passages. Visitors descend by underground train—a unique world experience. Nearby, Predjama Castle is literally built into a 123-metre cliff.

Europe's largest cave system

Postojna Cave forms a 24km network of underground passages—Europe's most visited cave system with over 39 million visitors since 1819. The 1.5-hour tour begins with a 3.7km journey aboard an underground train through immense chambers decorated with stalactites and stalagmites formed over millions of years. Temperature remains constant at 10°C year-round—bring a jacket even in summer.

The proteus, dragon of the caves

The caves are home to the proteus (Proteus anguinus), a blind, unpigmented amphibian locals call the 'baby dragon'. At 25-30cm long, it can live over 100 years and survive a decade without food. It's the world's largest cave-dwelling animal and endemic to the Dinaric karst. A vivarium within the cave allows observation.

Predjama Castle

Ten kilometres from Postojna, Predjama Castle is built directly into a 123-metre cliff—the world's largest cave castle according to Guinness. Built in the 13th century, it was the stronghold of Erazem Lueger, a Slovenian knight-brigand akin to Robin Hood. A secret passage through the cave behind the castle allowed him to withstand sieges. Entry: €18 alone or €40 combined with caves.

Practical information

Postojna is 50 minutes from Ljubljana via motorway (exit Postojna). Cave entry alone: €29.90 adults; combined caves + castle: €43.90 (2024 prices). Online booking recommended in summer. Tours every hour 9am-5pm (more frequent in summer). Allow half a day for caves plus castle. Caves are wheelchair-accessible. Free parking.