Opatija to Postojna Cave and Predjama Castle: Day trip

Postojna Cave is the most visited natural attraction in Slovenia and one of the great cave systems of Europe — 24 kilometers of passages, galleries, and subterranean halls formed over five million years by the Pivka River cutting through the Karst limestone.

What to see

• The cave train — a narrow-gauge railway takes visitors 3.7 kilometers into the cave before guided tours on foot begin
• The Concert Hall — a vast cavern large enough to hold classical concerts, its acoustics shaped by centuries of geological formation
• The Proteus anguinus (human fish) — the cave's famous troglodytic amphibian, blind and white-skinned, visible in the aquarium section of the tour route

Take note

• The cave temperature is a constant 10°C — bring a layer. Guided tours last approximately 90 minutes and depart regularly throughout the day; book tickets in advance at postojnska-jama.eu

Predjama Castle clings to the mouth of a cave halfway up a 123-meter cliff face in the Karst plateau — the most dramatically sited medieval fortress in Europe, and the former stronghold of the outlaw knight Erasmus of Lueg, whose defiance of the Habsburg emperor became Slovenian legend.

What to see

• The castle's four floors of rooms built directly into the cave — passages lead through the mountain to a hidden natural exit that allowed Erasmus to resupply during a year-long siege
• The cave system behind the castle — the Postojna Cave system extends for kilometers behind Predjama; separate cave tours are available
• The cliffside exterior — the approach from the valley floor gives the full impact of the castle's seemingly impossible position

Take note

• The castle is open year-round; the nearby Postojna Cave makes a natural pairing for a full day's visit