Hochburg castle was founded probably by Dietrich von Hachberg in the 11th century - although the first written mention dates from 1127. Between 1553-1577 the fortifications were completely remodeled and seven bastions were added in the early 1600s. Hochburg was however destroyed by catholic forces in the Thirty Years' War in 1634-1636. The reconstruction and modernization took place in 1660-1678, but it was again destroyed by German volunteers in 1681 to prevent an attack by French forces. The final destruction occured in 1688 by troops of Louis XIV.
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.