Mjøskastellet

Mjøskastellet is a medieval castle ruin located on Steinsholmen island in Lake Mjøsa, constructed with stone walls approximately three meters thick. The structure sits at the northern end of the lake near Moelv and was built using locally quarried limestone.

King Håkon IV Håkonsson ordered construction around 1230 to secure control over water transport and maintain authority during regional conflicts. The building later served as a state prison and became an important tool for managing the lake's strategic value.

The castle demonstrates how medieval rulers controlled important trade routes by placing fortified buildings at strategic locations. The site shows how power was exercised through dominance over water transportation.

The site is most easily reached by boat since the island lies in the lake and is not accessible on foot. Visitors should arrange boat transport in advance or check for guided tour options to access the ruins.

The building later became a state prison and earned the nickname 'Mjøsa's Alcatraz' because of its isolated island location. This surprising second life shows how the function of a defensive structure could transform completely over the centuries.