Akershus Fortress

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 prison. The first construction on the castle started around the late 1290s, by King Haakon V, replacing Tønsberg as one of the two most important Norwegian castles of the period (the other being Båhus). It was constructed in response to the Norwegian nobleman, Earl Alv Erlingsson of Sarpsborg’s earlier attack on Oslo. The fortress has successfully survived all sieges, primarily by Swedish forces, including those by forces led by Charles XII in 1716. In the early 17th century, the fortress was modernized and remodeled under the reign of the active King Christian IV, and got the appearance of a renaissance castle. The fortress was first used in battle in 1308, when it was besieged by the Swedish duke Eric of Södermanland, whose brother won the Swedish throne in 1309. The immediate proximity of the sea was a key feature, for naval power was a vital military force as the majority of Norwegian commerce in that period was by sea. The fortress was strategically important for the capital, and therefore, Norway as well. Whoever controlled Akershus fortress ruled Norway.