The Kajaani Castle was built on the Ämmäkoski island of the Kajaani river in the 17th century. The castle functioned as a administrative centre, a prison, and a military strongpoint. The most famous prisoner in the castle was the historian Johannes Messenius, who was forced to live in the poor conditions of the castle from 1616 to 1635.
Construction of the Kajaani castle began in 1604 and was completed in 1619. At first the castle only consisted of a stone wall, two round towers, and wooden buildings at the yard inside the castle.
Count Peter Brahe ordered a second construction stage of the castle, which was started in the 1650s and completed in 1666. During this construction stage, many wooden structures of the castle were replaced with stone structures to form a fortress.
During the Great Northern War (also known as the "Greater Wrath"), Russian forces sieged the castle for several months, until it was finally forced to surrender because of lack of food, firewood and ammunition. Shortly after this, the Russians exploded the castle and its inhabitants were transported to Russia to be imprisoned.
References: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.