Geiselstein, Mountain summit in Ammergau Alps, Germany

Geiselstein is a 1,882 m limestone peak in the Ammergau Alps of southern Bavaria, a free-standing rock pyramid whose north face drops about 400 m into the valley. Its four faces differ: deep water grooves on the north wall, wall and edge climbing on the east, cracks and corners on the south, short sport routes on the west. The summit is reached only by experienced, sure-footed climbers.

Geiselstein is built of Upper Rhaetian limestone of the Lechtal Nappe, Northern Calcareous Alps. The summit and northern part are massive facies, the south is oolitic facies. The steeply north-dipping north limb of the Wetterstein Saddle was squeezed over Jurassic beds along a shallow south-dipping thrust, deforming them; further north toward Bockstall follows a trough with the Lower Cretaceous Branderfleck Formation.

The mountain's name comes from the shadow it casts on the neighbouring Hochplatte when the sun shines. Its free-standing rock pyramid is sometimes called the "Matterhorn of the Ammergau Alps". The four faces are named by orientation and used for different climbing styles.

The mountain can be reached via several marked hiking trails, with the most straightforward access starting near Halblech. Sturdy footwear and weatherproof clothing are important, especially given the changeable conditions found at higher elevations.

The steep limestone cliffs offer excellent opportunities for technical climbing routes that see active use during warmer months. This rock formation makes the peak appealing not only to hikers but also to experienced climbers from the surrounding area.