Burg Altpernstein, Medieval castle in Micheldorf in Oberösterreich, Austria.

Burg Altpernstein is a medieval fortification located at 900 meters elevation between Kirchdorf and Micheldorf in Upper Austria. The castle has thick stone walls, multiple rooms serving different purposes, and is protected by a natural rocky ravine rather than a traditional moat.

Built around 1000 and documented in 1160 and 1207, the castle passed from Pillung von Pernstein to the Truchsen family, who converted the fief into free property. In 1337 Eberhard V. von Walsee bought it, and in 1394 Duke Albrecht III enfeoffed Johann I. von Liechtenstein, who was later imprisoned here with his family. From 1581 the Jörger family built the long hall; in 1629 their heir sold the estate to Stift Kremsmünster, owner ever since.

The name Pernstein probably comes from Bärenstein, as the Pernstein lords bore a brown bear on a yellow field. The castle chapel was built around 1340 by Eberhard V. von Walsee, who installed a chaplain there. The outer gate still carries old iron harnesses and breastplates fixed before the second Turkish siege of Vienna, in use for at least 320 years.

The castle stands at 800 metres above sea level, roughly 400 metres above the Kremtal valley, and is reached only over the masonry bridge that replaced the drawbridge in the 18th century. The entrance sits at the lowest point of the saddle-shaped rock; from the guest terrace the rock can be seen rising on the valley side to just below the roof of the third storey. The terrace and the castle tavern are open to the general public, and an archery course and via ferrata start right by the castle.

The outer gate was once the innermost of three doors in the gatehouse. Before the second Turkish siege of Vienna it was studded with old iron harnesses and breastplates, which still remain on the gate, in use for at least 320 years.