The first fort in Isein was built by bishop Atto of Freising in 784-811 AD. The current Burgrain castle dates from 1200s, when the lords of Burgrain built a four-winged building with keep and moat. The extensive additions and renovation was made in the 15th century by bishop Nicodemus.
After the secularization in 1804 Burgrain castle has been in possession of several owners. In 1906 it was converted into a home for blinds. Since 1919 it has been a private residence.
The castle church dates from 1719 and is richly decorated with rococo plasterwork.
See Burgrain from the Air
https://www.youtube.com/watch?v=EfFImys6EGw
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.