By 1034, Sterrenberg was being mentioned as an imperial castle, but the source is not certain. In 1190, Sterrenberg Castle is listed in the book of Werner von Bolanden as a fief, together with the custom point in Bornhofen. The noble family of Bolanden stayed as lords of Sterrenberg Castle until the second half of the 13th century. From this early period, the bergfried and the first, inner shield wall have survived.
References: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.