Postojna Cave

<p>Postojna Cave is the best known of Slovenia's karst caves and the one that made cave tourism an industry. The system runs to some 24 kilometres, and the visit begins unlike any other: passengers board an open narrow-gauge train that rattles several kilometres into the rock before the walking tour starts, through galleries of stalactites, curtains and pale flowstone columns. Guides have been leading visitors through since 1824, which makes this a two-century-old tourist attraction as much as a natural one.</p><p>Its most famous resident is the olm (<em>Proteus anguinus</em>) — a blind, pale, cave-dwelling amphibian that can live around a hundred years, survive years without food and regrow a lost limb. Locals long took the creatures washed out by floodwater for baby dragons, and the cave's Vivarium now keeps them on show; a clutch of eggs that hatched here became an international story. Between the train, the scale and the dragons, it is the single best introduction to the Slovenian underground.</p><p><strong>Planning your visit.</strong> Entry is by guided tour only, on fixed timed departures — there is no wandering in on your own. Allow about an hour and a half from departure to return, and book a slot online in advance: Postojna is Slovenia's busiest sight and popular departures sell out in summer. Because the time is fixed and the visit swallows the best part of two hours once you add parking and the walk to the platform, treat the cave as the anchor of the day and fit Predjama Castle, 9 km away, around it rather than the other way round.</p>