Predjama Castle, the fortress that moved into a cave

A castle built into the rock

According to the park that runs it, the castle has been wedged halfway up a 123 m rock face for more than 800 years. It is the largest cave castle in the world, listed by Guinness World Records, and the Slovenian Tourist Board describes it the same way. Behind the façade lies a network of secret tunnels connecting the castle with the cave directly below. The park places it among the ten most fascinating castles in the world and says it is so romantic that many couples choose to marry there.

Beneath the castle runs the Lokva river, which disappears underground at the foot of the cliff. That combination of rock, cave and water explains why the castle was almost impregnable, and why life inside had to put safety before comfort.

The legend of Erasmus

The story everyone tells here is that of the knight Erasmus of Predjama. A rebel, he held out in the castle against the imperial army’s siege for more than a year, helped by a secret tunnel that led outside. In the end a servant betrayed him, and according to legend he died while using the toilet. The Tourist Board also notes that a knights’ tournament in his honour is held at Predjama every summer.

The castle has appeared in documentaries and feature films, and the park says it impressed George R. R. Martin and that a Discovery Channel team went looking for ghosts inside.

What to see inside Predjama

The tour covers the armoury, chapel, kitchen and torture chamber, which help you picture what everyday life was like for those who held it. For me, the best part is the attic, with its view over the valley and a collection of plate armour and medieval weapons, from lances and halberds to swords, bows and crossbows. The guide comes as an app included with the ticket.

The cave beneath has four levels and is Slovenia’s second longest, according to the park. Part of it is seen on a guided tour and the rest on adventure tours, but only from June to August, because a bat colony hibernates there the rest of the year. A few steps from the entrance, the Stara Dama museum shows First World War objects and a hunting collection from the Notranjska forests.

The castle treasure lay hidden in the cellar for centuries and only came to light during the 1990 to 1993 restoration. Today it is on display at the Notranjska Museum in the centre of Postojna.

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Tickets, the Postojna combo and hours

The castle opens all year, with hours that change by month, and ticket sales stop thirty minutes before closing. A castle-only ticket costs €24, and the park also sells it in packages with Postojna Cave, €58.90 for the two and €84.50 for the whole park. You buy tickets on the official website, and package attractions can be visited within 30 days of the cave tour.

The park itself suggests starting with the castle and saving the cave for after lunch. With a package you do not have to cram both into a single day either, since the castle part stays valid for a month after the cave, which suits anyone staying in the area for a few days.

Getting there from Postojna

The castle is about 9 km from the Postojna Cave entrance. In high season a shuttle runs between the park entrance and the castle for holders of tickets to both; outside those dates, go by car or taxi, which you can arrange at the park ticket office. Ljubljana bus station’s search showed no line to Predjama in October 2026, as I explain in the Ljubljana to Postojna guide, so without a car the practical choice is an organised trip.

Castle lovers will find it ranked against the others in castles in Slovenia, where Predjama has a place of its own.

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