Kreuzberg was first mentioned as Cruceberg in a document in 893. Around 1100, the settlement came under the ownership of the Counts of Are, who built an initial residential house for one of their administrators on Kreuzberg. It is often stated that the bergfried (keep) of the castle was built during the 15th century. However, it is quite possible that this part of Burg Kreuzberg belongs to the oldest section of the complex and dates back to the 14th century. French troops destroyed the castle in 1686.
Today the main castle rises on an almost triangular ground plan, following the structure of the artificial castle plateau. The area is surrounded by the inner curtain wall. On the north side of the main castle area stands the baroque, two-story residential building made of rubble stones.
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.