The Fortress can be visited
Fortress Germersheim-Kommandantur

The Germersheim Fortress, a royal Bavarian fortification in the Palatinate city of Germersheim, was financed by the German Confederation. It served as a part of a Western German fortress system designed to protect against potential French attacks.
History+
After Germersheim became French in 1792, the French built new fortifications, which were reinforced in 1814 after the Bavarian takeover. The German Confederation recognized Germersheim's strategic importance as a hub for troop concentration in the event of a French attack in 1815. The city was a military center, representing a potential Rhine crossing for attackers from the south. Surveying work began as early as 1818, but the decision to build the fortress was made only in 1832.
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: 49.2181, 8.3745