The largest above-ground relic of tin extraction in the Graupen district is the Große Pinge (“Big Sink-hole”), just below the summit of the Komáří hůrka (808 metres above sea-level). Records concerning underground mining at this location go back to 1416. The sink-hole developed as the result of the excavation of a 140 x 45 metre greisen deposit primarily containing tin and copper ores. At roughly 75 metres deep, the depression – covering approximately 5,000 square metres – was formed by the collapse of the underlying excavated chambers. Dürrholz adit, the most important adit in the district, has drained water from the area since the end of the 15th century. Surrounding the sink-hole were a series of other mines, including the Glatz mine. With the help of a whim shaft, tin and copper ore were extracted from a depth of up to 200 metres from the 1680s onwards.