Saint Peter's church in Grou was built in the first half of the 13th century out of tuffstone. Already in the 13th century the church was heightened. In the 15th century the church was lengthened to the west and heightened for the second time with brick. The current tower dates from the early 15th century. The monumental Pipe organ was built in 1853 by L. van Dam & Zn. from Leeuwarden.
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.