Katzenelnbogen originated as a castle built on a promontory over the river Lahn around 1095. The lords of the castle became important local magnates, acquiring during the centuries some key and highly lucrative customs rights on the Rhine.
The castle was damaged by fire in 1540 and it was restored to current appearance in 1584 and 1613.
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.