This national nature monument - known as a stone organ is situated near the village of Prácheň near Kamenický Šenov. This geological formation is made of basalt columns (in pentagonal or hexagonal shapes) with mostly vertical orientation. In the 19th and 20th centuries this quarry was used to mine basalt columns. When mining activities were stopped, the mined quarry was filled with rain water, creating a small lake which is now a part of the National Nature Monument. Since 1895 the Panská Rock has been protected as a rare natural geological formation and it is the oldest geological reserve in the Czech Republic. It is accessible on foot and by bike.