The Fortress can be visited
Fortress Germersheim-Ludwigstor

The Ludwigstor (Ludwig Gate) is a component of the former Germersheim Fortress, a Royal Bavarian installation in the Palatinate city of Germersheim. This fortress was financed by the German Confederation and served as an element in the Western German defense system, designed to protect against French attacks.
History+
The origins of the fortifications in Germersheim date back to 1792 when the French, after taking control of the city, established new defensive lines. These were reinforced in 1814 following the Bavarian takeover. As early as 1815, the German Confederation recognized Germersheim's strategic importance as a hub for troop mobilization in the event of a French assault. Initial surveys began in 1818, but the decision to construct the fortress was made only in 1832. Under the direction of Friedrich von Schmauß, construction commenced on June 30, 1834, with the excavation of the main moat.
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: 49.2217, 8.3714