This castle held the Coyanza Council in 1050; the old Coyanza was populated and fortified by Fernando II of León in the second half of the 12th century. The current castle was built in the 15th century. It was constructed on the site of older castle that had been erected on the ruins of a fortification dating back to the Iron Age.
The castle consists basically of one articulated front with projections, flanked by turrets overshadowing the tower of homage, with round turrets in the Gales and fronts.
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.