First mentioned as Soban, Sobień Castle was a Royal castle guarding the merchant route along the San River. The castle was built by order of King Casimir the Great in 1340. In 1389 Władysław II Jagiełło conferred the castle to a noble family of Kmita.
The castle was destroyed in 1474 and again in 1512 by Hungarian forces. In 16th century the Kmita family sold the estates and the castle to Stadnicki family, who held it until 1713.
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.