Helga Trefaldighet (Holy Trinity) Church was inaugurated in 1302. It replaced the previous church of local Ullerås parish. The church is made of grey stone and brick and it was originally a three-nave basilica. The western tower was added in the 15th century. The church was damaged badly by fire in 1702.
The interior is particularly notable. It is decorated with paintings by the famous medieval artist Albertus Pictor, which were created in the second half of the 15th century. Of particular interest is the depiction of The Visitation, regarded as one of the finest surviving medieval paintings in Sweden.
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.