The former "Rotsch" quarry in Walhorn is now an important natural and cultural monument in East Belgium. Originally, limestone and dolomite were mined here, which significantly influenced the region's economic development. After its closure, the quarry filled with water and developed into a popular local recreation area for hikers and nature lovers. In 2021, the first International Walhorn Sculpture Symposium was held on the site of the former quarry. Seven European artists created large-format sculptures from local Aachen bluestone. These works of art form the sculpture trail "In the Footsteps of the Stones," a 3-kilometer circular path around the flooded quarry.