Ernstbrunn castle became the seat of the Ernstbrunn branch of the Counts of Sinzendorf in 1592. After the last Sinzendorf died in 1822, it was inherited by the Köstritz branch of the ruling princely House of Reuss of whom it remains their main family seat until today.
The castle is an elongated structure with four ascending courtyards on the northern slope of the Semmelberg above Dörfles. The medieval core castle on the northern rocky spur was continuously expanded during the Late Renaissance, Baroque, and Classicism periods with new groups of buildings. The core castle, dating from the 12th and 13th centuries and surrounding the innermost courtyard, sits on a free-standing limestone rock on three sides, which drops steeply towards the village of Dörfles. It forms an elongated octagon. The wall thickness of the outer wall is up to three meters. It is further reinforced on the southeast by the square keep. Originally, this keep had only three floors but was extended by an additional floor in the 16th/17th century.
In front of the gate is an early Baroque fountain. This fountain has a total of 16 coat of arms representations, 4 at the top of the shaft below the fountain bowl and 12 in pairs around the edge of the hexagonal basin.
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.