Olavinlinna (literally Olaf's castle) is a 15th century castle, which is located in Savonlinna, Eastern Finland. It's known for example a stage of Savonlinna Opera Festival since 1912. The Kalmar Union intended Olavinlinna orginally as a military fortress and it was founded by Erik Axelsson Tott in 1475. Olaf's castle is today a popular year-round tourist attraction, for it's beautiful architecture and landscape of lakes, with over 85,000 visitors in year.