The Town Fortification can be visited
Town Fortification Andernach-Rhein Gate

The Andernach-Rheintor city fortification is located in Andernach, Rhineland-Palatinate. As the oldest double gate system in the Rhineland and the only surviving main gate of the former city fortifications, it is a historical structure of medieval defensive architecture in the region.
History+
Around 1200, the Rheintor was built as the northern main gate of Andernach's city fortifications, serving as the central access point from the Rhine. Originally named “Korenpor(t)zen” after the Korngasse, it received its current name in the early 19th century. Initially, the gate consisted of the inner gate with a pointed tent roof and two painted figures that served as guardian symbols. In the mid-14th century, the outer gate was added with a trapezoidal gatehouse.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Lothar Spurzem / CC BY-SA 2.0 de via Wikimedia Commons
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: 50.4410, 7.4011