You’ll get a blend of natural and man-made wonders on this tour, all tucked away in sleepy south-western Slovenia. We start at Postonja Cave, a 24-kilometre maze of craggy natural tunnels and halls. Stalagmites give the impression of carved pillars, and a gaping space nicknamed the “concert hall” has even hosted symphony orchestras. You can walk around parts of the underground network, but there’s also a mini railway to ferry you through the caverns. Once you’re back above ground, it’s straight to the 700-year-old Predjama Castle. This Renaissance stronghold has to be seen to be believed – it’s wedged right in the middle of a 120-foot vertical cliff. Passages weave below ground to a vast cavern, making this one of the only preserved cave castles in Europe.
- SUITABILITY Moderate physical activity.