The Fortress can be visited
Fortress Germersheim-Fronte Beckers

The Germersheim-Fronte Beckers Fortress, a historical structure in Germersheim, Rhineland-Palatinate, Germany, was part of the Royal Bavarian Fortress of Germersheim and played a role in the German Confederation's defense system against attacks from France.
History+
The origins of Germersheim's fortifications date back to 1792 when the city was under French rule and initial defensive structures were built. These were strengthened after Bavaria took over in 1814. In 1815, the German Confederation recognized Germersheim's strategic importance as a military hub for repelling French invasions across the Rhine. Initial surveys began in 1818, and the decision to build the fortress was made 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: 49.2172, 8.3675