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.
Fortress (disambiguation) A fortress is a fortification, a defensive military construction.