Kuusisto Castle was a medieval episcopal castle built in the beginning of the 14th century. It was the main residence of Finnish Catholic bishops until 1522, when the last bishop Arvid Kurki drowned when fleeing from Danish soldiers.
Kuusisto heyday was in the in the beginning of the 15th century, when bishop Maunu Tawast spent lot of time and money to enlarge the castle. The castle was ordered to be demolished during the Protestant Reformation in 1528 by the king Gustav I of Sweden. Stones of the castle were later used in renovations of Turku and Kastelholma castles.
Excavation and reconstruction work on the remaining ruins began in 1891.
Visby Cathedral (also known as St. Mary’s Church) is the only survived medieval church in Visby. It was originally built for German merchants and inaugurated in 1225. Around the year 1350 the church was enlarged and converted into a basilica. The two-storey magazine was also added then above the nave as a warehouse for merchants.
Following the Reformation, the church was transformed into a parish church for the town of Visby. All other churches were abandoned. Shortly after the Reformation, in 1572, Gotland was made into its own Diocese, and the church designated its cathedral.
There is not much left of the original interior. The font is made of local red marble in the 13th century. The pulpit was made in Lübeck in 1684. There are 400 graves under the church floor.