The edifice of Olavinlinna, castle of St. Olaf, began in 1475. The Danish-born founder of the fortress, Knight Erik Axelsson Tott, decided that an authoritative fortification should be constructed to guard the tactically significant Savo region. The castle was supposed to keep away Russian attacks from the east and to pledge the control of the Savo region for the Swedish Crown. The history of Olavinlinna is a fusion of medieval arms conflicting, cannons roaring and every-day errands inside the security of the castle's thick walls. The changes in the possession of the castle left their mark on Olavinlinna: this can be seen in the diverse architecture of the fortress. These days the castle's halls and rooms can be rented and used for all kinds of events.