Kastelholm Castle, Åland

The only medieval castle in Åland, built in the 14th century beside a bay in Sund. Next to it, the Jan Karlsgården open-air museum shows traditional Åland farm buildings and a windmill, and the Vita Björn prison museum.

Nearby are the ruins of Bomarsund, a Russian fortress destroyed by the British and French during the Crimean War in 1854. Kastelholm is about 25 km from Mariehamn.