The Fortress can be visited
Federal Fortress Ulm-Courtine mit Blaubeurer Tor
The Federal Fortress Ulm-Courtine with Blaubeurer Tor is an example of 19th-century fortress architecture and part of what was once Europe's largest fortress complex. It is located in Ulm, Baden-Württemberg, Germany.
History+
The Federal Fortress Ulm was constructed between 1842 and 1859 and was one of five federal fortresses designed to secure the internal territories of the German Confederation after Napoleon's defeat. The design originated from Moritz Karl Ernst von Prittwitz und Gaffron, who also oversaw its construction. The Courtine with Blaubeurer Tor, built from 1843 to 1855 under Major von Schele, connected the Mittelbastion with the Kienlesbergbastion.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: https://commons.wikimedia.org/wiki/File:Blaubeurer_Tor.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: 48.4020, 9.9781