Burg Ardey, Medieval castle ruins in Fröndenberg, Germany.

Burg Ardey is a medieval castle ruin in Fröndenberg located on a wooded hilltop where the Ostholzbach stream flows into the Ruhr River. The site features stone walls, defensive ditches, and building remnants scattered across steep slopes.

The castle was built around 1176 as the seat of the Lords of Ardey, whose dynasty ended in 1318. Following the extinction of this noble line, the fortress lost its political importance.

The name Ardey comes from the noble family that built the castle and called itself Lords of Ardey from 1176. In the Middle Ages a court bench stood on the Vorburg, the outer bailey east of the main castle, which was separated from the surrounding land by its own ditch; it survived until the 19th century.

The site is accessible via steep slopes that require good footing to navigate safely through the ruins. A visit during dry weather is recommended to avoid slipping on the hillside paths.

Local legend tells of a knight named Embert who allegedly threw treasures into a well at the castle. This tale remains part of the region's folklore and adds mystery to the ruins.