St Pol de Léon's Church is said to have been founded in 490 by Paul Aurelian, a Welsh saint. The church building is medieval but was largely destroyed in a raid by the Spanish in 1595. It was rebuilt by 1600. The parish tower is constructed of granite with double buttresses. It is 27m tall and is surmounted with a turret 6.1 m tall, which serves as a daymark for shipping in Mount's Bay. The tower contains six bells.
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.