Postojna Cave is the most visited cave in Slovenia, and it’s not hard to see why. It has been visited by more than 40 million people in the last 200 years, with people from all over the world flocking to the cave to experience its subterranean wonderland.

Postojna Cave comprises a 24-kilometre long karst cave system – the largest in Slovenia! – and has been carved out by the Pivka River over the past two million years.

The cave runs regular tours throughout the day, which are segregated by language. Not all of the cave is open to the public; guests can only access a 6-kilometre stretch. Visitors cover 2 kilometres on constructed walkways and, here’s what is really unique about Postojna Cave, the remaining 4 kilometres on a nifty electric train!

The first railway opened in 1872, with local guides manually pulling visitors in wagons. This has now evolved to a fully electric train, which will make you feel as if you’re flying through space as you whiz through large rock caverns. The temperature in the cave does tend to be a little chilly at approximately 10 degrees celsius so do remember to bring an extra cardigan along.

Once you disembark, a guide will bring you through several halls, offering running commentary every step of the way. On display are numerous magnificent stalactites, which grow downwards from the ceiling due to water dripping down through the deposit of calcite, and stalagmites, which grow upwards and grow in size from the drips of water. Columns are formed when these stalactites and stalagmites join together.

The walkways are mostly over flat terrain, and are both wheelchair stroller friendly. Those that wish to stay on the train can also do so as you’ll take the train out again at the end of the tour.

You’ll also be able to spot unique variations like spaghetti stalactites and curtains! It’s important not to touch any of the formations or use a flash when taking pictures.

Highlights of the tour are the ‘Skyscraper’, a 16-metre tall stalagmite that’s said to be around 150, 000 years old, as well as ‘Brilliant’, a 5-metre tall bright white stalagmite that’s the icon of Postojna Cave.

Feast your eyes on other interesting formations such as ‘Romeo and Juliet’, which is the result of two columns joining into one’ and the ‘Organ’, which resembles an organ in a church choir.

Doesn’t the ceiling look like it’s covered with a dusting of petrified icicles? This section of the cave is naturally called the ‘Spaghetti Cave’.

In the ‘White Hall’, the stalagmites are white due to the presence of concentrated calcium carbonate.

In the ‘Red Hall’, on the other hand, the stalagmites are a reddish-brown, its rust colouring derived from the iron minerals in the soil above.

Other than the fascinating rock formations, the cave is home to more than 100 species! Majority of these are insects and spiders, but the most interesting of all is the Olm. Colloquially referred to as a baby dragon or a human fish, the Olm is a blind creature that looks much like a salamander. The creature can grow to about 12 inches long and can live to 100 years old! It can also go without food for 10 years at a time. Thousands of these reside naturally in the cave and visitors can view some of them in a large aquarium.

The last room that you’ll visit is the ‘Concert Hall’, a large cavernous tavern that can hold an echo for up to 5 seconds! The splendid acoustic features have seen the area being used for various concerts, performances and even for a basketball event. The hall is so huge that it can hold up to 10, 000 people at a time. The room also holds the oldest underground post office, where you can send a letter back home as a souvenir.

Postojna Cave is open all year round, even on holidays. From November to March, the cave offers 3 guided tours a day at 10am, 12pm and 3pm. From April to October, there are tours every hour from 9am to 6pm. The entry fee for adults is around EUR25.8 (~SGD40).

While there are thousands of caves in Slovenia, Postojna Cave certainly stands out among the rest. Located just 40 minutes by car from Ljubljana, Postojna Cave is commonly visited together with the nearby Predjama Castle and medieval town of Skofja Loka.

Read: Things to Do in Ljubljana, Slovenia; Visit Predjama Castle, a Castle Built Into a Cave in Slovenia