Postojna is a small town in the Notranjska region, between Ljubljana and the coast. The town itself holds little tourist interest: people come here for Postojna Cave (24 km of underground passages, an underground railway, and the 'Brilliant' stalactite hall) and Predjama Castle – a medieval fortress built into a 123-meter cliff face, 9 km from the cave. This is Slovenia's most visited attraction: over 39 million visits since it opened in 1819. Nearby is the lesser-known Planina Cave, where an underground river surfaces.
From Ljubljana – 50 minutes by car via highway (you'll need an eVinjeta), 1 hour by train (€5.80, trains every hour), or 50 minutes by bus (€5–10). Postojna sits on the Vienna–Venice railway line, with direct trains from Zagreb, Koper, and Salzburg. From the train station to the cave is a 25-minute walk. Most visitors come for half a day – enough for the cave and the castle. If driving, note: parking at the cave costs €6/day, at the castle €3/hour. The combo ticket for cave + castle starts at €46.50 (cheaper than buying separately). Temperature inside the cave is 10°C year-round – bring a jacket.
