The most visited tourist cave in Europe is a place where the proteus or olm offspring are once again hatching. The cave railway has been operating at the cave for 140 years. Predjama Castle is located close to Postojna Cave and is the largest cave castle in the world. It is the only karst cave with a railway, which was built more than 140 years ago. The unique tourist train will take you to the underground network of karst corridors, galleries and halls. The most important karst features there are: the largest, 16-metre-high stalagmite known as the Skyscraper, the crystal white symbol of Postojna Cave – the Brilliant, the oldest underground post office in the world and the most famous underground animal – the olm or the human fish.