St. Katharinen, Medieval monastery in Stendal, Germany.

St. Katharinen is a single-nave Gothic brick church with a five-sided polygonal apse, a gabled roof and a small ridge turret, built between 1472 and 1490. Buttresses divide the walls, and pointed-arch windows are wider in the nave and narrower in the choir. A medieval cloister wing with ribbed vaults survives, and the former monastery buildings now house the Altmärkische Museum.

Founded in 1456 by Elector Frederick II of Brandenburg as a Benedictine convent, the monastery adopted the Augustinian rule after 1469. The church was consecrated between 1472 and 1490, built on the site of the Hospital of the Holy Spirit. In 1540 the Reformation turned it into a women's collegiate foundation, dissolved in 1945; the church and cloister were restored in 1985–1986.

The monastery houses a museum where visitors can see exhibitions about the history and daily life of the Altmark region. The collections show local crafts, traditions, and objects that reveal how people lived in this area over centuries.

The site is accessible and guided tours are available to explore the complex with explanations of its architectural features. Visitors should allow time to see both the church and the surrounding buildings and courtyards.

In the second bay on the north wall hangs the former bell of the Katharinenkirche, cast in bronze in Salzwedel by master C. B. Behrens in 1759; its four-line Latin inscription names the convent, the Domina von Vinzelberg and the administrator Andreas Warnicke as those who paid for it.