The first mention of Graville Abbey was in the 9th century. Considered to be a masterpiece of the Romanesque art in Normandy, the abbey underwent several periods of construction since the 11th century. The church's nave and transept date from the Romanesque period. Guillaume Malet de Graville, who was victorious during the Hastings battle alongside William the Conqueror, as well as his descendants, invested their fortune in preserving the riches of this monument. Today conventual buildings are converted to a museum.
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.