To be privately owned
Velde Castle (Boves)

In Boves, North Rhine-Westphalia, Velde Castle is a historical building whose origins date back to the 13th century. The former knight's estate is now a Renaissance structure.
History+
Haus Velde was first documented in the 13th century. The current building complex was partly constructed in the early 16th century. A coat of arms on the main facade in the inner courtyard bears the year 1527 and the initials of the then owners, who were involved in the redesign of the knight's seat. Their structural alterations have partly been preserved to this day. At the rear of the main house, the ruin of an old staircase can be found, which once provided access to a defensive tower within the complex. Of the former outer fortifications, only a large watchtower remains, which still guards the entrance. Haus Velde served as a fief for knights who, on behalf of the Electorate of Cologne, secured the border with the Duchy of Geldern.
Source: Wikipedia · Licence: CC BY-SA 4.0
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 51.3931, 6.4002