Virtsu Fortress was one of the strongest medieval country castles in Estonia. The aim was to control ship traffic in the Great Strait and the crossing between the islands and the mainland. A castle with two towers adapted for firearms was built around 1450. The builder was the vassal of the bishop of Saare-Lääne, Uexküll. Virtsu Castle was detroyed in the winter of 1533-1534 and was no longer rebuilt. In 2014, the conservation work of the fortress was started.