Annenberg castle was built in the 13th century (first mentioned in 1252). At the end of the 15th century the castle was largely extended by the lords of Annenberg and the ring wall with the four towers was laid out as a consequence of the Swabian War. The castle started to decay at the end of the 17th century.
The central Palas was restored to habitable again in the early 1900s.
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.