The remains of the Castle can be visited
Château du Grand-Geroldseck

In the commune of Haegen in the French department of Bas-Rhin is the Château du Grand-Geroldseck, a castle ruin. It is among the oldest fortifications in the northern Vosges and shows a combination of residential and defensive architecture.
History+
The origins of the Château du Grand-Geroldseck date back to the early 12th century. It was built by the Lords of Geroldseck, the advocates of Marmoutier Abbey, to protect their territories. In the 13th, 14th, and 15th centuries, the complex underwent alterations and expansions. As early as 1898, the castle ruin was recognized as a historical monument by the French Ministry of Culture.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://en.wikipedia.org/wiki/File:Petit-Geroldseck.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: 48.7187, 7.3326