Ingolstadt

Ingolstadt is a German city located along the Danube River.

Indiana Jones and Charles de Gaulle were imprisoned at Dusterstadt near Ingolstadt in 1916. Though the pair managed to escape, De Gaulle was recaptured.

Behind the scenes
De Gaulle was a prisoner of war at Ingolstadt but The Young Indiana Jones Chronicles episode "Germany, Mid-August 1916" (edited into Trenches of Hell) and its novelization use a prison fortress called Dusterstadt instead.

Without naming it, Indiana Jones: The Ultimate Guide refers to Dusterstadt as a "high-security prison at Ingolstadt, Germany".