Schloss Allner

Schloss Allner is a fifteenth-century castle in Rhein-Sieg-Kreis, North Rhine-Westphalia, Germany. It is located on the southern slope of the Nutscheid Ridge, on the north bank of the River Sieg, and just northeast of the Allner See. It lies to the northeast of the town of Hennef, east of the district of Allner.

During its history it has served as a residence, a municipal seat and an orphanage. During World War II it was the scene of an unsuccessful attempt by the Wehrmacht to halt the advancing Allied forces from crossing the Sieg and entering the Ruhr Valley.