All the castles mentioned so far were erected by the Swedish Crown in order both to defend Finland as part of the Kingdom, and to organize administration and taxation through the bailiffs.
However, there was one more fairly big castle which played an important part in the history of the Finnish part of the kingdom of Sweden throughout the Middle Ages. This castle, called Kuusisto (or Kustö in Swedish), lay just southeast of Turku, where building work commissioned by the Bishop in Turku had started in 1317.
Kuusisto Castle, Finland
This bishop was one of a total of seven in the kingdom of Sweden and his bishopric was the second largest, stretching all the way from Viborg in the east to Finnish Lapland in the north. Since the bishop was also a member of the council of the realm, he was not just an ecclesiastic but a political figure as well, and this was one reason why he needed a fortress: he also kept a private army. When the Muscovites besieged Viborg in 1495, Bishop Magnus III was able to contribute one hundred armed knights to its defense.
Kuusisto today is a ruin, because Gustavus Vasa ordered its destruction in 1528 as part of his battle against the Catholic Church after the Reformation. However, it is still possible to see that the castle comprised a keep and three baileys. There are the remains of gun towers, probably built in the 1480s, at the corners. Cannons were necessary to protect the Bishop in his stronghold.
Author: Carl Jacob Gardberg, Photo: Jouni Heikkinen/Vastavalo