Visiting Kastelholm Castle - Åland's only medieval castle

Writer: Helena Bergström

Updated: August 2026 | Kastelholm Castle is Åland's only medieval castle and one of the archipelago's most interesting historical sights. Royals, governors and prisoners have passed through here over the centuries – including Gustav Vasa, Johan III and the deposed king Erik XIV. Today you can explore the castle and at the same time visit the Vita Björn prison museum and the Jan Karlsgården open-air museum.

Kastelholm Castle

Kastelholm Castle had its historical heyday under Gustav Vasa and his sons, when Åland and Finland were part of Sweden. After several fires, the castle finally fell into disrepair, but today it is once again a living place.

As well as visiting the restored and well-preserved ruin, you can also see the Vita Björn prison museum and the Jan Karlsgården open-air museum, and enjoy food and drink at Smakbyn and the Åland Distillery.

Kastelholm Castle is located in Sund, Åland.

Kastelholm Castle - with an exciting history

Kastelholm Castle was built at the end of the 14th century as a defence castle. Over the years, many different owners came and went, the most famous being the Swedish Vasa family. Both Gustav Vasa and Duke Johan stayed here, and Gustav Vasa turned the castle into a hunting lodge. Erik XIV was also imprisoned here for a few months.

Why was Erik XIV imprisoned at Kastelholm Castle?

Kastelholm Castle is strongly associated with the Swedish Vasa dynasty. Gustav Vasa resided here and used Åland for hunting, among other things, while his son Duke Johan – the future Johan III – had Turku Castle as its most important residence in Finland.

Family relations were complicated to say the least. Johan came into conflict with his brother Erik XIV, who had him imprisoned. A few years later the balance of power reversed: Erik XIV was deposed as Swedish king in 1568 and Johan became King Johan III instead.

In 1571, the deposed Erik XIV and his wife Karin Månsdotter were taken to Kastelholm Castle, where they were held captive for a few months. It is quite a dizzying thought when you walk around the castle today – here was a former Swedish king imprisoned on the orders of his own brother.

Sieges and fires

Kastelholm Castle has been involved in several power struggles and conflicts over the centuries. During the Engelbrekt Rebellion in the 1430s, the castle was besieged, and it was also subject to battles and unrest in the following centuries.

Administrative centre

Until 1634, Kastelholm was the administrative centre of Åland and the castle was rebuilt several times. The last governor, Stellan Otto Mörner, tried to rebuild the castle after a fire in 1619, but eventually it lost its importance.

From decay to museum

The following fire, in 1745, destroyed almost the entire castle, which then fell into disrepair. The building has undergone several extensive restorations and is now a museum.

Visiting Kastelholm Castle

Visiting Kastelholm Castle today is very interesting. Because the castle is so well preserved, there is a lot to see in the form of rooms, towers, arches, stairs, a well and much more.

In summer, you can walk here with a guide. Since we were here in pre-season, we went on our own, but there were still hosts here and there - dressed in period clothes - who were happy to answer questions and embroider the occasional exciting story.

Peter was in a playful mood and found the box of period clothing. Why not try out one of those chainmails for once? Phew how heavy it was! How did they manage to fight? Not to mention the hassle of getting it off again... It was lucky that one of the experienced hosts came with some tips and tricks!

White Bear Prison Museum

When visiting Kastelholm Castle, you can also check out the White Bear Prison Museum, which is right next door and included in the same ticket.

Kastelholm has a long history of handling prisoners, from the dark dungeons under the castle to the remand centre in Vita Björn. For almost 200 years the Crown Prison was used and it was here, in the jailer's living room where he lived with his family, that prisoners had their sentences read out. Perhaps a death sentence or life banishment to Siberia.

Across the hall were the prisoners' cells. Today they have been reorganised so that there is one cell from the 19th century, one from the 1850s, one from the 20th century and one from the 1950s. Even though the storage became more humane over the years, these walls have a lot of gruesome stories to tell ...

Open air museum Jan Karlsgården

Right next to Kastelholm Castle is the Jan Karlsgården open-air museum. When the museum was founded in the 1930s, it was named after Jan Karls in Finström, where the manor house comes from.

Today there are around 20 buildings in the area, all of which have been moved here from different parts of Åland. You can see houses and stables, but also different kinds of mills and an interesting exhibition about the Post Road.

At certain times of the year, various events are also organised here, such as the Midsummer celebrations on Midsummer's Eve and the Christmas market in December.

Flavour village

Right next to Kastelholm Castle is Smakbyn, which is known for its distillery and pub, and also has a small stall selling delicacies. It also organises cooking classes, wine tasting and other activities.

Åland Distillery

Here is also the Åland Distillery, where we had a meal. It was a soup with pike and root vegetables for me (Helena) and a pizza with different cheeses for Peter. Good and nice!

We also bought some of the distillery's long drinks for the camper.

Accommodation and motorhome at Kastelholm

There are various accommodations in the area around Kastelholm and Sund. If you are traveling with a camper or caravan, you can also find campsites elsewhere in the surrounding area.

We lived on our own. Puttes camping at Bomarsund Fortress, which is a short drive from Kastelholm. Then we continued to Vårdö and Sandösund campsite, where we stood nicely with a view of the water.

More to see and do in the neighbourhood

If you like historical sights, there is more to discover near Kastelholm Castle in Åland. Here you will find tips and reports:

• Bomarsund Fortress
• Things to do in Mariehamn
• Things to do in Åland