Olavinlinna castle

Olavinlinna, St Olaf's Castle, stands on a rock island at Savonlinna in eastern Finland, in the Kyrönsalmi strait between the lakes Haukivesi and Pihlajavesi. It is the northernmost medieval stone fortress still standing and the best preserved of all the medieval castles of the old Swedish realm.

It was a provocation from the first stone. In 1475 the Danish-born knight Erik Axelsson Tott began building it to stake Sweden's claim on the frontier, after Ivan III of Moscow had swallowed Novgorod and announced that Finland was next. The Russians said the castle stood on the wrong side of the border and attacked the barges bringing sand, stone and lime to the island. Modern research has shown they were right: it went up about five kilometres inside what was then Russian territory. With no master builder in Finland equal to the job, Tott wrote in 1477 of "16 good foreign master bricklayers" on the island, probably from Reval, today's Tallinn. Theirs was the first Swedish castle built with thick round towers to stand up to cannon. The three-towered keep was finished in 1485 and the outer walls in 1495; Ivan's armies besieged it in 1495 and 1496, and it held.

Olavinlinna was never taken by force. Its garrison surrendered twice instead, to invading Russians in July 1714 and again in August 1743, after which the Treaty of Åbo handed the castle and the whole region to Russia. The Thick Tower blew up in 1791, and fires in the 19th century destroyed every original furnishing.

At its fullest about 200 people lived inside the cold, damp walls. Every year the castle raised a black ram for the feast of its patron saint, St Olaf, at the end of July, and that ram is the hero of its best-loved story. With an enemy at the walls, the legend says, the ram climbed up onto the ramparts, stamped its hooves on the stone and swung its great horns, and the attackers, convinced the devil himself lived in the castle, ran. Since the 1960s a statue of the ram has stood on Tallisaari island beside the fortress. The castle has darker tales too, of secret passages, a water spirit in the black current, and its most famous legend, a young castle maiden walled up alive as punishment for treason. Not every story is necessarily true, says the national museum that runs it, but some may hold a grain of truth.

In 1907 the singer Aino Ackté came to a patriotic gala in the courtyard and saw a stage. The first Savonlinna Opera Festival followed in 1912, and every summer since 1969 opera has filled the bailey, where a covered stand now seats 2,114.