The Nebenwerk C (Werk 125) is located in the inner fortress ring
Fortress Ingolstadt-Nebenwerk C (Werk 125)

Nebenwerk C, auch als Werk 125 bekannt, ist ein Bestandteil der ehemaligen Ingolstadt Fortress. Es liegt im inneren Festungsring der Stadt.
History+
The Ingolstadt Fortress, a fortification of the Bavarian Army, was created through the conversion of medieval fortifications and later extensions. Five main construction phases can be distinguished. Nebenwerk C belongs to the inner fortress ring. In addition to the preserved medieval city wall, many later fortress works still exist today. After World War II, there were considerations to remove the remaining fortress works, but these plans were abandoned. Since then, particularly the Neoclassical structures have been restored and given new uses.
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: 48.7879, 11.4328