[PAR] [TLE] Akershus Fortress [SEP] Akershus Fortress (Norwegian: "Akershus Festning" ) or Akershus Castle (Norwegian: "Akershus slott" ) is a medieval castle that was built to protect Oslo, the capital of Norway.  It has also been used as a palace and as a prison. [PAR] [TLE] Festning Tunnel [SEP] 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.
[PAR] [TLE] Akershus Fortress [ SEP ] Akershus Fortress ( Norwegian : " Akershus Festning " ) or Akershus Castle ( Norwegian : " Akershus slott " ) is a medieval castle that was built to protect Oslo , the capital of Norway . It has also been used as a palace and as a prison . [PAR] [TLE] Festning Tunnel [ SEP ] 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 .
The Festning Tunnel runs under what type of structure?
The Festning Tunnel runs under what type of structure ?
a medieval castle
a medieval castle