The most historically significant area of the Graupen mining district lies north of the town of Krupka below Komáří hůrka mountain. More than 150 tin mines operated here from the medieval period through to the late 18th or early 19th century. The number and density of the mines is unusual both for the Erzgebirge and for Europe. The landscape is shaped by dozens of collapsed shafts and adit mouths, as well as by various heaps ranging from small raised mounds to large, flat heap structures. These are easily visible on old maps or images created using modern laser scanning techniques. The distance between the heaps roughly matches the old mine measurements dictated by the 1487 Graupen mining code: either 36 x 36 metres or 72 x 36 metres.