Adendorf castle is the successor of a high-medieval castle located to the west of today's site. The small castle hill is few hundred meters from the current palace and was in the 14th century owned by the family of Hüchelhoven.
Arnold von Adendorp built a new castle from 1337 at its present location. It was besieged and conquered by the army of Henry III, Landgrave of Upper Hesse, in the late 15th century.
In 1659-1663 the medieval castle was transformed as a representative Renaissance schloss. Another reconstruction took place in 1842. The changes included the filling of the moat between the outer bailey and main building.
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.