The castle of Toolse was built in 1471 by the Livonian Order as defence against pirates sailing in the Gulf of Finland. During the Livonian War it changed hands several times, was apparently destroyed and later rebuilt. In 1581 French mercenary Pontus de la Gardie captured the castle for Sweden from Russia which had held it since 1558. The castle was destroyed again during the Great Northern War, ever since which it has laid in its current state of ruin.
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.