Výpustek Cave 2026: from prehistoric bones to a Cold War nuclear bunker

Výpustek has the most unusual story of any cave in the Moravian Karst — around 1600, doctors from all over Central Europe travelled here for bones passed off as “unicorn horn”, during the Second World War it served as a Nazi armaments factory producing aircraft engines with 1,200 workers a day, and between 1961 and 2001 it was a top-secret command post of the Czechoslovak army, designed to withstand a 30-kiloton nuclear blast. It only opened to the public in 2008. The tour lasts 75 minutes and covers 600 metres. Flat-rate admission is 490 Kč (approx. €19.60 — this is a rough guide only, exchange rates fluctuate), family tickets 1,700–2,150 Kč.

QUICK LINKS 🦄 The hunt for the unicorn horn · 🎟️ Admission and route · ❓ FAQ

If you’ve spent the other caves admiring stalactites, at Výpustek you’ll be looking at concrete instead. It’s the only cave in the region where you’ll see not just natural underground spaces but an actual military bunker — and that’s exactly why, for many visitors, it’s the most fascinating cave in the whole of the Moravian Karst.

From the hunt for the unicorn horn to a military bunker

Výpustek is one of Europe’s few sites to have yielded complete skeletal remains of Pleistocene fauna — the upper chamber preserves rich phosphate sediments packed with the bones of Ice Age animals. It was precisely this abundance of bones that turned the cave, for centuries, into an unexpectedly sought-after destination — for medicine, not tourism.

Around 1600, the famous alchemist and physician Oswald Croll came here in search of the tusks and bones of extinct proboscideans, which he ground down into so-called unicornu fossile — a powder sold as ground unicorn horn, reputedly able to cure almost anything. Thanks to the cave’s reputation for “unicorn horn”, physicians from across Central Europe flocked to Výpustek throughout the 17th century. The first written description of the cave was then compiled in 1663 by the Premonstratensian canon Martin Alexandr Vigsius — the same man who was also the first to describe the neighbouring Křtiny Valley (see separate article).

The cave’s more recent history, however, is far more dramatic. It had already served the First Republic’s army as a weapons and ammunition store. Towards the end of the Second World War it was seized by the Germans, who set up an aircraft engine factory here — running round-the-clock shifts with up to 1,200 workers and 120 clerical staff a day.

The strangest chapter begins in the early 1960s, when the cave was taken over by the Czechoslovak People’s Army amid rising international tensions. A concrete structure was built into the rock massif, which for decades served as a backup command post for southern Moravia — with capacity for 250 officers, its own air-conditioning system, air filtration, generators and accommodation facilities. The structure was designed to withstand a direct hit from a 30-kiloton nuclear bomb, and in the event of a crisis could have operated independently for several days. It was only removed from combat-readiness status and declassified in 2001, with the cave opening to the public in 2008.

Admission and route

The tour route covers 600 metres and takes around 75 minutes — one of the longer tours in the region. The path leads through both levels of the cave, with a height difference of 55 metres; temperatures range between 7–9 °C with high humidity of around 95%.

Alongside the standard tour, Výpustek also offers an experiential route called “In Search of the Secrets of Výpustek Cave” for groups of up to 10 people aged 6 and over, which requires advance booking — it’s available year-round.

Frequently asked questions

Is there any truth to the unicorn horn story? Around 1600, the alchemist Oswald Croll and other physicians of the era came here for the bones of extinct proboscideans, which they ground into the “miracle” remedy unicornu fossile — in reality, of course, these were ordinary tusks and bones, not genuine unicorn horn.

Why is Výpustek different from the other caves of the Moravian Karst? It combines a natural cave with a genuine military bunker and centuries of history stretching back to Baroque-era medicine — and between 1961 and 2001 it also served as a secret backup command post for the Czechoslovak army.

Is Výpustek suitable for children? Yes, but given its military history and longer tour (75 minutes), it’s more appealing to older children and adults than to very young children.

When did the cave open to the public? Not until 2008, after being removed from combat-readiness status and declassified in 2001.

What is the “In Search of the Secrets of Výpustek Cave” experiential route? A special tour for smaller groups (up to 10 people) requiring advance booking, available throughout the year.

Part of the series A Week in the Moravian Karst: a complete 7-day itinerary. Sources: Czech Cave Administration – Výpustek Cave, history, characteristics, opevnovani.cz, Ochrana přírody magazine, AOPK ČR, Musil, R. et al. — “Moravský kras: Průvodce Josefovským a Křtinským údolím”, MUNI Press 2019 (contents). Prices and opening hours are subject to change — we recommend checking the official website before you travel.