Olavinlinna Castle: Finland's Medieval Island Fortress in Savonlinna

Most castles in Finland sit on hills or by the sea. Olavinlinna sits on a rock in the middle of a fast-flowing strait, with lake water on every side and three round towers rising straight out of the stone.

It is the kind of building that looks almost too perfect to be real, especially on a still summer evening when the walls are mirrored in the water. Yet Olavinlinna Castle is very real, and very old: more than five centuries of war, fire, neglect and repair are written into its masonry.

It stands in the town of Savonlinna in eastern Finland. It is the northernmost medieval stone fortress still standing, and the best preserved of the medieval castles built in the old Swedish realm. Here is how it came to be, how to read it, and how to plan a visit.

A Border Fortress Founded in 1475

The castle was founded in 1475 by Erik Axelsson Tott, a powerful nobleman who held the Swedish fief of Vyborg. He named it Sankt Olofsborg after Saint Olaf, the Norwegian king who became one of the most popular saints of the medieval North. Olavinlinna is simply the Finnish version of that name.

The timing was political. Ivan III of Moscow had just conquered the Novgorod Republic, and the border between Sweden and Russia was disputed. By building in Savonia, Tott planted a stone claim on land that Moscow regarded as its own side of the old treaty line.

The site was chosen with care. The island lies in the Kyrönsalmi strait, which links the large lakes Haukivesi and Pihlajavesi. The surrounding maze of lakes and waterways would slow down any army trying to reach it.

Built for the Age of Cannon

A letter written by Tott in 1477 mentions foreign builders invited to the site, probably from Reval, today's Tallinn, where the city walls were being extended at the time. Their influence shows in the most important design decision: thick, round towers.

Olavinlinna was the first Swedish castle to be given a set of heavy circular towers meant to stand up to cannon fire. Round walls deflect shot better than flat ones, and they leave no blind corners for attackers to hide in.

The three-towered keep was finished in 1485, on the western side of the island. Work on the outer curtain walls began immediately, and those walls, with two more towers, were completed in 1495. Seen from above, the whole complex forms a rough, truncated rhomboid that follows the shape of the rock.

How to Read the Walls Today

The castle you see now is not exactly the one Tott built. One of the keep's original towers, St Erik's Tower, stood on a weak foundation and eventually collapsed. In the bailey, the so-called Thick Tower exploded in 1791, and a solid bastion was built in its place.

That bastion points to the next chapter. In the late 18th century, after the region had passed to Russia, the fortress was modernised into a bastioned fort in the style of the French engineer Vauban. The Russian general Alexander Suvorov personally inspected the rearmament.

So when you walk around Olavinlinna, you are looking at two eras layered together. The tall round towers and grey fieldstone belong to the late medieval Swedish castle. The low, angular earthworks and bastions belong to the Russian military engineers who adapted it for a later kind of warfare.

Sieges, Surrenders and a Town Is Born

Olavinlinna was besieged several times by Russian forces and was never taken by storm. Life inside, though, was hard. At its busiest the castle held about 200 people, and it was a cold, damp place to live, especially in winter.

Trade grew up under the protection of the walls towards the end of the 16th century. That market settlement became the town of Savonlinna, which received its town charter in 1639. In Swedish the town is still called Nyslott, meaning new castle.

The garrison did agree to terms of surrender twice: to invading Russians in July 1714, and again in August 1743. After the second war, the Treaty of Åbo handed the castle and the surrounding region to the Russian Empire, and its role as a frontier fortress slowly came to an end.

Fire, Neglect and a Long Restoration

In the 19th century the castle lost its military purpose, and fires destroyed much of its interior. Its original furnishings were lost. After two bad fires in the 1870s, the question of what to do with the old fortress became urgent, and the state began caring for it as a historic monument.

Repairs were carried out in the late 19th century and again during the 20th century. The last major restoration started in 1961 and was finished in 1975, just in time for the castle's 500th anniversary. Since then, only smaller annual repairs have been needed.

Today the building is owned by Senate Properties, the Finnish state's property agency, and run as a museum site by the National Museum of Finland. If you are curious how it compares with the country's other great defensive monument, read our guide to Suomenlinna, Helsinki's island sea fortress, built almost three centuries later for a very different kind of war.

The Savonlinna Opera Festival

For many visitors, Olavinlinna means opera. In the summer of 1912, the Finnish soprano Aino Ackté organised the first of five opera festivals in the castle. The modern Savonlinna Opera Festival, held every summer since 1967, grew out of those early events.

Performances take place in the main courtyard, which is covered for the season and seats 2,264 people. The orchestra plays from a pit in front of the stage, and operas are sung in their original language with subtitles in Finnish and English.

A few practical points help. Evening performances usually start at 19:00, and latecomers wait until the first interval. The courtyard can be cool even in July, the stone floors are uneven, and everyone passes a bag check before the bridge, so bring a warm layer, wear sturdy shoes and arrive early.

What You Can See Inside

Olavinlinna is open all year. Your ticket includes a guided tour of about an hour, which takes you through the halls and rooms of the main castle and along the defensive walkways. The upper levels of the towers can only be visited on a guided tour.

In June, July and August, English tours start on the hour every day. In May and September there are fewer English departures, and in winter the regular tours are in Finnish, so book an English guide in advance if you visit off-season.

Without a guide you can explore the three courtyards and two small museums. The Castle Museum shows objects found in and around the fortress, while the Orthodox Museum displays icons and other religious items from Finland and Russia. A history exhibition uses models and replicas to show daily life in different eras.

Planning Your Visit to Savonlinna

Savonlinna lies in the Finnish Lakeland, roughly 330 kilometres north-east of Helsinki. You can reach it by car, by long-distance bus or by train, and in summer the town is also a hub for lake cruises. The castle is a pleasant walk from the town centre, across a short bridge to the island.

Opening hours change through the year, and the castle closes on certain holidays, so check the National Museum of Finland's page before you go. Ticket sales and the entrance close 45 minutes before closing time.

Be aware that the castle was built to be hard to get into. The courtyards are paved with rough natural stone, the steps are steep, and many doorways are low and narrow. Prams and pushchairs cannot go on the guided tours.

A Castle Worth the Journey

Olavinlinna is not on the way to anywhere, and that is part of its appeal. It rewards visitors who make the trip into the Lakeland with a rare, almost complete picture of a late medieval frontier castle, still surrounded by the water that defended it.

If castles are what draw you north, it pairs well with Denmark's Kronborg Castle in Helsingør, another fortress that guarded a narrow stretch of water. For more buildings in this part of the Nordic region, browse our directory of notable buildings in Finland.