The Kehlburg castle was built probably in 933 By the bishop Altwin of Brixen at the hillside over Gais. The most important owners later were the noble family Rost zu Aufhofen, which had the castle in possession for nearly three centuries.
After the fire in 1944 where the castle was nearly completely destroyed, the chapel of the holy Erasmus was rebuild so this was used for many years as a much visited pilgrimage. Unfortunately the castle and the chapel is damaged by vandalism.
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.