What Fortress used as a palace and prison has the Festning tunnel running underneath it?
Festning Tunnel The Festning Tunnel (Norwegian: "Festningstunnelen" ) is a motorway tunnel on European Route E18 in the city center of Oslo, Norway. The tunnel has two tubes, with three lanes in each. It runs from Bjørvika, under Akershus Fortress, The City Hall Square and Vika to Filipstad. The tunnel is 1800 m and -45 m elevation at the deepest.
Poznań Fortress Poznań Fortress, known in German as Festung Posen (Polish: "Twierdza Poznań") was a set of fortifications in the city of Poznań (German: "Posen") in western Poland, built under Prussian rule in the 19th and early 20th centuries. It represents the third largest system of its kind in Europe.