Akershus Fortress was constructed along the coastline of the Oslo Fjord around 1299 as a defense against sea and land invasions. Akershus Festning successfully repelled at least six attacks by Swedish, Danish and Scottish soldiers from 1308 through the 16th century. The citadel was only surrendered in 1940 when Germany invaded Norway during WWII. The Germans used the big building on the right, called the Akershus National Penitentiary, as a military prison. Further on the right is the Crown Prince’s Powder Magazine Tower (circa 1755). It was used by the Nazis as death row for Norwegian Resistance fighters. The castle was liberated in 1945. Akershus Fortress is surrounded by Crown Prince’s Bastion, a stone wall built in 1618.