Adventure in the caves below st. Pieterberg hill

Do you dare go underground? Not afraid of the dark? Go exploring in the caves below the St. Pietersberg hill. No light, no sound, no radiation, no pollution, no mobile phone signal, no idea of time…
Through a labyrinth of corridors, a professional guide takes you underground to see the names and drawings of people who worked here every day a few hundred years ago. These so-called 'block breakers' were manual labourers cutting out blocks of marl. The marl blocks were used to build houses, churches and castles – and marl is still used in construction today. Napoleon and the Duke of Alba saw these caves with their own eyes. Their names were once scratched into a cave wall. You can extend a visit to the caves with a visit to a unique spot: national storage location no. 9, better known as 'the vault.' About 780 artworks, including Rembrandt’s Night Watch, were stored here until the end of the 'Second World War!
The subterranean network of caves in the St. Pietersberg hill was not formed naturally. Human hands created this labyrinth of mine galleries by cutting and hacking out blocks from the ancient layer of soft limestone. What you see today is the rock that the block breakers left behind. The labyrinth once had 20,000 passageways covering a total of 200 kilometres. The labyrinth currently has 8,000 passageways, measuring a total of 80 kilometres in length. It is very easy to get lost. Bats have no trouble with that; they feel completely at home here. The marl was formed when the calcium-rich skeletons and shells of a variety of creatures accumulated on the bed of the sea that was here many millions of years ago. The fossilised remains of those creatures can still be seen today in the yellow marl used in buildings in the city and on the walls of the passageways. The most impressive finds date from 1770, 1998, and 2012, when particularly well-preserved fossils of mosasaurs (literally: Meuse lizards) – relations of the dinosaurs – were found in the St. Pietersberg hill.
Due to their air of mystery and their vastness, the catacombs also gained great strategic importance during the dozens of sieges on the fortified city of Maastricht. Battles were even fought right into the caves by the nearby Fort St. Pieter.
An enormous explosion took place below the fort in 1794, creating a huge underground dome, which can now be visited safely. The passageways also served as a place of refuge for the inhabitants of Maastricht and the surrounding area during wartime. Wells were dug in the Zonneberg caves, an entire hospital ward was set up, and a bakery and a chapel were built. The remains of these can still be seen. In September 1944, Maastricht’s residents sheltered in the bombproof safety of the caves, while above ground the city was being liberated.

Standard tours are also offered in English for our international visitors in the North Caves and Fort St Pieter (every day all year round) and in the Zonneberg Caves starting 2016 (weekends only).

We also offer a variety of tailored activities and programmes in all our locations, for both adults and children. Take a look under Activities and Kids for a complete overview.