The manors of Kirburg and Wissen originally belonged to the noble lords of Freusburg, who presumably also built Schönstein Castle. Through the marriage of their heiress, Aleidis von Molsberg, to Eberhard von Arenberg, the properties came into the possession of the Lords of Arenberg, Burggraves of Kurköln, in 1176. Eberhard and Aleidis' sons divided the property along the Sieg River. Heinrich received the land south of the river, including Schönstein, and continued to be known as 'von Arenberg,' while Gerhard received the properties north of the river and became known as 'von Wildenburg.' After the extinction of the Arenberg lineage in the male line in 1280, the Archdiocese of Cologne seized the parish of Wissen to the left of the Sieg River as a lapsed fief. From 1281, Schönstein Castle served as a pledged object for the Archdiocese of Cologne. The Wildenburger Land with Wildenburg fell to Johann von Hatzfeldt († after 1407) through the heiress Jutta von Wildenburg.
In 1589, Hermann von Hatzfeld-Werther received Schönstein Castle as a recognition of his services from Kurköln. By then, the castle had suffered significant damage, and in 1594, Hermann von Hatzfeldt-Werther estimated the maintenance costs at 16,000 gulden. During the Thirty Years' War, the castle was occupied, looted, and set on fire by Swedish troops, but it was rebuilt on the initiative of Wilhelm von Hatzfeld. Since 1912, Schönstein Castle has served as the administrative seat of the Hatzfeldt-Wildenburg Chamber.
Today, it is also the residence of the von Dönhoff family.
The main building, which has an approximately triangular floor plan, is a typical courtyard castle, with the buildings arranged around an inner courtyard. It has been built or restored from the Middle Ages to the present day, making the architectural history quite intricate. The brick facades from the late 16th century stand out from the older north wing with its rubble masonry. The baroque staircase in the south wing was built in the first half of the 18th century. Of interest is the two-story wooden gallery on the east wing. The first floor was built in 1598, and the second floor in 1623.
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.