Akershus Castle and Fortress

You can also visit Akershus Castle and Fortress. The fortress is strategically located at the entrance to Oslo Harbour and has survived several sieges over the years. The fortress dates back to the Middle Ages, but was rebuilt by Christian IV, and Queen Margrethe I lived in the castle for the first part of her life. In the castle you can see the eerie dungeon, which was also used as a prison during the Second World War.