Between 1115 and 1118 the Augustinian monastery was established in Sankt Märgen by Count Bruno von Haigerloch-Wiesneck, Chancellor of Henry V and Provost of Straßburg, as competition to the Zähringen-founded Benedictine monastery of St. Peter auf dem Schwarzwald. The town and the monastery were dependent upon each other for many years. In 1716 a two-steepled Baroque monastery church was built, and the life of the community underwent a revival, until 1806 when the monastery was given up.
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.