The Tauern Window is a geological structure in the Austrian Central Eastern Alps. It is a window (in German fenster) in the Austroalpine nappes where high-grade metamorphic rocks of the underlying Penninic nappes crop out. The structure is caused by a large dome-like antiform in the nappe stacks of the Alps. The relatively hard rocks of the Tauern Window are more resistant to erosion, so the window has a high relief. The mountain chains thus formed are called the Hohe Tauern. Most of Austria's highest mountains are in the Hohe Tauern, among them the Großglockner (3798 m) and Großvenediger (3674 m).