Burg Rahden, Medieval castle in Rahden, Germany

Burg Rahden is a ruined water castle in the Kleinendorf district of Rahden, near the Große Aue. Its rectangular complex measured about 63 by 53 metres, enclosed by a moat fed by the river, with access from the south over a drawbridge at today's Lemförder Straße. The main building, a stable, a gatehouse and a connecting wing stood here, with a massive keep attached to the main building and towers on the north and south sides.

The fortress was founded in 1296 and served as the seat of different noble families across several centuries. Ownership changed hands repeatedly due to financial hardships that affected the stronghold's fate.

The castle gave its name to the noble family von dem Rode, recorded in the 13th century as vassals of Ludolf von Steinfurt and later as landowners in Fiestel and Rahden. A stone door lintel recovered from the ruin in the early 1980s commemorates Christian, Duke of Brunswick-Lüneburg, the 59th Bishop of Minden, and was probably installed in 1619.

The ruins are located behind the museum grounds within a park and can be viewed at any time. Free parking is available and there are no entrance fees or access restrictions for visitors.

A stone door lintel recovered from the ruin in the early 1980s and set up in front of it bears an inscription commemorating Christian, Duke of Brunswick-Lüneburg, the 59th bishop of Minden (1566–1633); it was probably installed in the castle in 1619. The north wall still leans noticeably to one side despite steel tie bars inserted in the 1990s.