Visiting the UNESCO Caves and Castles of Postojna and Predjama, Slovenia

Slovenia's Karst region features some of the planet's most astonishing limestone caves and daring medieval fortifications. 1. Postojna Cave Underground Railway Ride an electric open-air train through vast subterranean chambers of towering stalagmites and meet the rare endemic proteus (human fish). 2. The Impregnable Predjama Castle Marvel at the world's largest cave castle, perched halfway up a 123-meter vertical cliff face with secret escape tunnels. Travel Tip: Cave temperatures remain a chilly 10 degrees Celsius year-round; bring a warm fleece jacket even in high summer. Uncover thrilling knightly history and breathtaking geological marvels in Slovenia.