Burg Aerzen, Medieval castle in Aerzen, Germany.

Burg Aerzen, also called Schloss Aerzen, is a castle complex at Burgstraße 1 in Aerzen in the Weserbergland. Its two-storey south wing has rubble-stone walls with Gothic window forms and two small barrel-vaulted cellars; the north wing is a three-storey rubble-stone building erected in 1533, and the west wing of around 1740 is a two-storey timber-framed structure containing the gateway to the inner courtyard.

The site was first documented in 1293 as 'borch Artelsen' and fell under the rule of the Counts of Everstein. After being burned by Weimar troops in 1642, it was rebuilt and received an additional half-timbered section in the middle of the 18th century.

The castle serves today as a gathering place for local associations and groups that use the premises for meetings and events. This shows how the site remains woven into the daily life of the community.

Burg Aerzen stands at Burgstraße 1 in Aerzen, in the Weserbergland south of Hameln. The site is not on elevated ground; the wings enclose a flat inner courtyard entered through a gateway in the west wing. The east wing, added later, closes the courtyard side that was once only a wall.

The tithe barn of 1561 no longer stands at the castle: since 1980 it has been in the Cloppenburg open-air museum. Two 18th-century stables still remain from the former farmyard, and the east wing, added only recently, closes a courtyard once bounded on that side by a wall alone.