Klosterburg Kastl, Architectural heritage monument in Kastl, Bavaria, Germany.

Klosterburg Kastl stands on a long dolomite ridge above the Lauterach valley near Kastl in Bavaria. The complex is a former Benedictine abbey built within the walls of an earlier hilltop castle; only wall remnants of the original fortress survive, incorporated into the buildings and the ring wall. A gate tower was added in the 14th century.

The site originated as a fortress during the Carolingian period and transformed into a Benedictine monastery in 1102. This conversion resulted from an agreement between three noble families with papal approval.

The site changed hands and purposes multiple times, reflecting different chapters of regional history. Visitors can still sense how a former defensive stronghold became a spiritual center and later served educational purposes.

Since 2023 the complex has housed the Bavarian police section of the University of Applied Sciences for Public Service, following renovation and conversion after the Hungarian Gymnasium closed in 2007. The grounds sit on a long dolomite ridge above the Lauterach valley, reached from Kastl by an uphill approach; the buildings are in institutional use, so visitors see the exterior and the ring wall rather than the interiors.

The 1102 papal confirmation by Paschalis II came only after Count Berengar of Sulzbach, Friedrich I of Habsberg-Kastl with his son Otto, and Luitgard of Zähringen, wife of Margrave Diepold II of Vohburg, settled their joint ownership between 1098 and 1102. Look for the 14th-century gate tower, built while the monastery was flourishing.