Caves of Maastricht

The Caves of Maastricht, also known as the caves of St Pietersberg/Mount St Peter[1] and the Maastricht Underground, is a collection of limestone caves in Maastricht, the Netherlands, the origins of which go back to the 13th century.

The caves were originally dug to mine Marl. Over time the caves formed a network so vast that it was used for other purposes.

The caves were eventually no longer used for mining, as the value of lime dropped, and an open-faced quarry was used instead. During World War II, the Cave complex was used to store many valuable paintings, and armaments that could be used against the Germans, including a proposed force of 30 tanks that would sortie against the Germans that was timed to attack at the same point of liberation.

In addition to the military, over 6,000 citizens took shelter in the caves during World War II. Over some hundreds of years, art has been drawn on the cave walls, providing an attraction to tourists who can tour some of the cave sections.[1] [2][3]

After the war, there were plans to utilise the underground complex as a bomb shelter.

The caves stretch over 300 kilometres long, and have 23,000 passages.[1]