Akershus is a castle built in the late 13th century as a defensive fortress of Oslo. Since the Middle Ages the building was the seat of the rulers of Norway. Due to its strategic location on the sea, the fortress was attacked and besieged several times, nevertheless, the attackers - including the Swedes - never managed to get it. It was only during World War II when the Akershus Fortress was passed to the Germans as a result of surrender and then served as a prison. Today the former fortress houses museums and the Akershus is one of the major tourist attractions in Oslo.
