Holzheim Castle dates to 1333, and its owners were vassals of the Duchy of Jülich. In the 15th to 17th centuries the manor house and gate tower were built, both of which have survived. In 1818, when the region was part of the Prussia county of Düren, the castle and its estates were sold to private buyers. In 1893 it was bought by Richard Schleicher, who also bought the nearby estate of Schönthal. The property later changed hands several times.
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.