Caves of Mount St PieterDating back to Roman times, the caves are an complicated labyrinth of thousands of man-made passages. The caves are the result of centuries of excavation of sandstone. The walls are covered with drawings and signatures, some of which go back to pre-historic times.Casemates Between 1575 and 1825, mining activities created a network of galleries at Maastricht's western limits. These mining galleries were used in times of siege for subterranean approach and elimination of