//
Sund's church is generally understood to be the second oldest church in Åland (and Finland) and the largest one on the archipelago. A Romanesque building characterized by a strong fortified tower, the church is generally opened for visitors in the summer months and host, besides church service, concerts and other events.
Kastelholms slott
A medieval castle in the mid-part of the mainland, worth paying a visit. Partly a ruin today, it was founded in the 1380s. There are guided tours in the high season (mid-June to mid-August), mostly in Finnish, but also in Swedish and English. An audio tour is available for Android devices. There are lots of staircases in the castle so the tour is not suitable for disabled people. Ticket price also include entrance to the Vita Björn prison museum.
The museum consist of a number of traditional buildings moved here from other parts of Åland to form a late-1800s agricultural farm. The main building is from Jan Karls homestead, hence the name. The area is open year round, but access into the buildings only in summer season. Kastelholm area tourist information centre and a good restaurant-cafeteria next door.
The Vita Björn served as Åland's prison for 200 years until 1975. There are four cells giving a glimpse on how prisoners' treatment changed from the 1700s to 1950s. The house include also the residence for the warden and his family and some prison related items like chains and a whipping pole are visible. Guide leaflets in separate languages. The entrance fee is included in the Kastelholm Castle ticket.
Bomarsund fästningsruin
The huge fortress (over 300 m in diameter) was built by the Russians in 1830–1854, but it was never completed, as the establishment was thoroughly ruined during the Crimean War by the allied English-Frenchmen. In 2022, brand new visitor center was built right by the ruins, where visitors are able to see pictures and objects related to the history of the fortress as well as films, models, etc.