Olavinlinna is the first Swidish fortress that served to repel attacks from the east and to guarantee control of the Savo region for the Swedish Crown. It was laid in 1475.
The castle is built on an island in the Kyrönsalmi strait that connects the lakes Haukivesi and Pihlajavesi, facing Saimaa. It withstood several sieges by the Russians during Russian-Swedish wars in XV-XVIII century. A brisk trade developed under the umbrella of the castle towards the end of the 16th century, giving birth to the town of Savonlinna, which was chartered in 1639
At present Olavinlinna is famous as the northernmost medieval stone fortress still standing. It has been among Finland's best-known tourist attractions since the latter 19th century. It houses museums of history, and orthodox icon painting.
Since 1912 Olavinlinna hosts Savonlinna Opera Festival is one of the most radiant and internationally significant events in the Finnish cultural calendar. Starting 1967 Opera Festival are held annually.
Read more : http://www.operafestival.fi.