The Hohensyburg, a castle complex of the Lords of Sieberg, was constructed on the grounds of a former Saxon refuge, which was conquered in 775 by the Franks under Charlemagne. The castle, which was built around 1100 of Ruhr sandstone, was partially destroyed in 1287 by Count Eberhard I. von der Mark. The castle complex was an imperial fief of the von der Mark counts from 1300. This fiefdom was transferred to Brandenburg in 1609, and later to Prussia.
Two keeps, residential quarters (two-chamber system), the wall ring and the walls around the courtyard complex are still recognisable. In the inside of the castle is a war memorial by Fritz Bagdons.
References:The Château du Lude is one of the many great châteaux of the Loire Valley in France. Le Lude is the most northerly château of the Loire Valley and one of the last important historic castles in France, still inhabited by the same family for the last 260 years. The château is testimony to four centuries of French architecture, as a stronghold transformed into an elegant house during the Renaissance and the 18th century. The monument is located in the valley of Le Loir. Its gardens have evolved throughout the centuries.