Visiting Predjama Castle and Postojna Cave is one of the must do day trips for your Slovenia itinerary. There are plenty of tour companies that package these two together for a guided visit, but we chose to rent a car and do it ourselves. Picking up a car in the city center was easy and it gave us the freedom to take our time at both locations.
The two sites are very close to each other (about a 15 min drive). If renting a car I would recommend visiting Predjama Castle first (ideally as soon as it opens) to beat the crowds from organised tours.
Entry times are staggered for Postojna Cave to manage the numbers on each cave train. It’s busy whenever you go, so just pick the best slot for you!
I recommend booking tickets ahead of time. The cave is the most visited paid tourist attraction in the country. Postojna Cave & Predjama Castle Tickets.
Predjama Castle
Predjama Castle might be one of the most unusual castles in the world. It’s literally built into the mouth of a giant cave halfway up a cliff. Recognized by Guinness World Records as the largest cave castle in the world, it’s also considered one of Europe’s best examples of architecture integrated with nature.
Behind the castle lies an enormous cave system filled with secret passages and tunnels. Unfortunately, the caves are only open during the summer months, so we missed the chance to explore them because we were just a little too early in the season.
Even without the cave tour, exploring the castle itself was incredible. It’s fascinating to see how rooms, kitchens, armories, and other parts of medieval life were built directly into the rock face. An hour is plenty of time to explore the castle before heading on to Postojna.
If you have time, there’s a cafe that has a lovely view of the castle near the entrance.
Postojna Cave
Postojna Cave is one of the world’s most visited karst cave systems and one of Europe’s largest show caves. The caves are part of the wider Postojna Park complex, which includes restaurants, cafés, and plenty of souvenir shops. Expect big crowds when you arrive, so factor in some time before your timed entry to find the right queue and get your bearings.
The tour began with one of the most memorable parts – boarding a small two-person cart on an electric train that takes you about 10 minutes deep into the cave system. From there, we continued on foot to explore further with the tour guide.
Exploring the cave was absolutely mind-blowing; genuinely one of the most incredible natural places I’ve ever seen. The vast caverns feel like underground cathedrals, filled with stalactites, stalagmites, and limestone formations that have developed over millions of years. Pictures couldn’t do justice to some of these caverns and formations!
The cave is also home to the olm, a rare blind amphibian that lives in its underground waters. Historically, locals believed these pale creatures were baby dragons washed out of the caves during floods.
Near the end of the tour, there’s a small, glass display tank with several of these little creatures. You’ll need to look closely as they’re easy to miss in the dim light.
Another interesting feature of the caves is the world’s only underground post office. Yep, if you feel like sending a post card down there, you’re in luck!
The experience exceeded expectations in every way and might have even sparked a new interest in spelunking.
If you’re planning a trip to Slovenia, make sure to also check out my posts on the Lake Bled day trip and things to do in Ljubljana.
Any questions? Just drop me a comment on one of my videos.
