The 15-mile (24km) Postojna Caves are arguably some of the most spectacular in the world. If you bring the family here, not only do you get to explore an ethereal, magical world, there’s an underground train ride which makes getting about the caves with tired, little legs very easy. The train passes between two-million-year-old stalactites, each stone structure seeming more amazing than the last. If your kids are eagle-eyed, they might spot the ‘baby dragons’ (which are actually 'olms', a reptile resembling a dragon native only to this region). When you surface, take the kids to the world's largest cave castle, Predjama. Here, they'll be enthralled by tales of the rebellious knight Erazem – a real character from the 15th century.

Ranked: Europe's finest family attractions