Held every July in the courtyard of Olavinlinna — a 15th-century island fortress rising from Lake Saimaa — the Savonlinna Opera Festival is one of the world's most spectacular opera settings. Full opera productions are staged under the open sky with the medieval walls as backdrop. Running since 1912, it is Finland's most prestigious cultural event and one of Europe's most atmospheric performing arts experiences. Tickets sell out months in advance.