The remains of the Castle can be visited
Château du Frankenbourg
On a mountaintop in the French Grand Est region lies the castle ruin Château du Frankenbourg. This site was once a strategically important point.
History+
The origins of the Château du Frankenbourg date back to the early 12th century. The castle initially served as the residence of the Lords of Frankenburg, who were vassals of the Diocese of Metz. Later, the complex passed into the possession of the Diocese of Strasbourg. Around 1135, the Counts of Werd, descendants of the Counts of Saarbrücken and vassals of the Hohenstaufen, took over the castle.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://commons.wikimedia.org/wiki/File:Frankenbourg_058.JPG?uselang=de
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: 48.2952, 7.3250