TheCaves of Maastricht, also known as the caves ofMount Saint Peter[1] or the Maastricht Underground, are a collection oflimestone quarries inMaastricht, theNetherlands, the origins of which date back to the 13th century.
They were originally dug to minechalk.[2] In total, a network of 20,000 tunnels were cut into the stone, of which 8,000 are still intact.[3]
The quarries were eventually no longer used for mining, as the value of lime dropped. Over the centuries, art was drawn on the quarry walls, providing an attraction to tourists who can tour some of the quarry sections.[1][4][3]
DuringWorld War II, the quarry was used to store 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.[citation needed] In addition to the military, over 6,000 citizens took shelter in the quarries during World War II.[1]After the war, there were plans to use the underground complex as a bomb shelter.
Among the paintings hidden in the quarries during WWII wasThe Night Watch byRembrandt van Rijn. The canvas which measures 363 × 437 cm was detached from its frame and rolled into a large cylinder.
A large portion of the former tunnel system no longer exists as the encompassing limestone was quarried in anopen-cast mine operated byENCI. Quarrying was ceased in 2018.[5]