Akershus Castle (Akershus slott) is a medieval castle that was built to protect Oslo, the capital of Norway. Also in different ages 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
Stone bridge to the castle
Tower
Inner yard
Soldiers barracks
Guard tower
Prison