Nonnenfelsen (Nun's Rock) is an approximately 150-meter-long sandstone rock massif located in the Lusatian Mountains geomorphological complex, which in Saxony is referred to as the Zittau Mountains (German: Zittauer Gebirge). The rock ridge with numerous rock towers and other rock shapes is located near the Czech-German state border on the outskirts of the village Jonsdorf in the district of Görlitz in Saxony. Nonnenfelsen are about 1 km away from the center of Jonsdorf, from the southwestern edge of this holiday village and climatic spa is only about 300 meters. The highest point of the massif reaches 537 m above sea level and on the southern side of the rock it is surrounded by the Pochebach stream. The rock that forms the Nonnenfelsen rock massif is a medium-grained sandstone, which comes from the Mesolithic period of the Upper Cretaceous. The restaurant in the northern part of the rocks was opened in 1860. The inn was gradually expanded, and when it burned down in 1902, it was soon restored. The dilapidated restaurant was closed in 1990 and was renovated until 1996.

The Nonnenfelsen massif is also a well-known climbing site. A number of local rock towers are used for climbing, usually around 25 to 30 meters high. Near the inn are the rocks Klettergipfel Nonnefelsen and Nonnenfelsen, then in the southwest there are the rock walls Schluchtwand and Neue Schluchtwand, behind them 25 meters high rock tower Barbarine and at the southwest end of the massif Nonnenturm. In the immediate vicinity are the famous rocks Jonsdorfer Monch, Mönchslochwarter, Buchbergspitze and Waltersdorfer Turm. A total of 16 climbing routes of difficulty from grades II and IV to grades VII and VIII of the UIAA are marked in the Nonnenfelsen massif. In 1994, members of the Zittau section of the German Alpine Association built a protected climbing route (via ferrata) Nonnensteig in the Nonnenfelsen massif.