The original castle on the Marienberg, a hill which was first settled in the late Bronze Age, was probably a small fort built early in the 8th century by the Franconian-Thuringian dukes, together with a church which in 741 became the first church of the Würzburg bishops. From 1200 an unusually large castle was built, which was extended during the late Middle Ages and the Renaissance.
Following the storming of the castle in 1631 by the Swedes, Prince-Bishop Johann Philipp von Schönborn built a circle of massive bastions to protect the Marienberg. In 1945 the fortress was almost completely burned out, and its reconstruction was only completed in 1990.
On the first floor of the Princes' Building Museum (administered by the Bavarian Palace Department), is the Bibra Apartment with valuable furniture, tapestries and paintings, the Princes' Hall with early Gothic arcatures and the large Echtersche family tapestry, as well as a treasury and vestment chamber from the era of the prince-bishops. On the second floor is the Main-Franconian Museum documenting the history of the fortress and town.
The 1,300 m2 Princes' Garden is accessible from the castle courtyard: it was reconstructed in 1937-38 on the basis of plans dating from the early 18th century.
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.