Burg Klein-Zimmern / St. Josephshaus, Water castle and cultural heritage monument in Klein-Zimmern, Germany.

Burg Klein-Zimmern is a water castle and cultural heritage monument near Groß-Zimmern consisting of upper and lower structures sharing a narrow ridge. The complex features a four-story residential tower with defensive walls and a 1966 Canisius Building that houses educational facilities and support programs.

Documents suggest the site existed by 1276, though its early history is poorly recorded because Klein- and Groß-Zimmern were often confused. In 1661 Johann Ludwig von Bettendorf sold the noble house and lands to Colonel Felix Biedenbach von Treuenfels for 3000 gulden. In 1688 the Biedenbach share passed to Baron Johann Philipp von Frankenstein for 2650 gulden. The St. Josephs-Knabenanstalt was founded in 1864 by Bishop Wilhelm Emmanuel von Ketteler.

The site became a youth welfare center in 1864 under Bishop Wilhelm Emmanuel von Ketteler, focusing on supporting children and young people in need. This transformation shaped the place as a space dedicated to care and education that continues this mission today.

The site sits on gently rolling terrain with paths allowing exploration of the grounds and outer structures. Note that much of the complex remains an active workplace and educational facility, so interior access may be restricted to certain areas.

During World War II the property served as a prisoner hospital where approximately 500 Soviet prisoners of war died. This tragic chapter is now remembered at the nearby Russian Military Cemetery.