To be privately owned
Château de Septfontaines

In Luxembourg, the Château de Septfontaines, a historic castle complex, stands above the village of the same name. The surviving remnants point to a long history.
History+
The first documented mention of an owner dates back to 1192 with Tider von Septfontaines, followed by Jean de Septfontaines in 1233. In the early 14th century, Thomas de Septfontaines, a close confidant of Emperor Henry VII, was lord of the castle. In 1600, Christoph von Criechingen had a Renaissance tower built at the northern entrance. A fire in 1779 led to the destruction of the complex, and in 1919, a part of the castle was demolished.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://en.wikipedia.org/wiki/File:Septfontaines_Castle.jpg
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: 49.7007, 5.9637