 The three high-medieval Finnish "castle fiefs" were ruled until the 1360s from the castles of Turku, Hämeenlinna and Vyborg.By the beginning of the 14th century, Turku Castle was one of the largest in northern Europe, with over 40 rooms and by the mid-16th century received further changes to withstand cannon fire.Construction of Vyborg castle started in 1293 by order of Torkel Knutsson, Lord High Constable of Sweden.