The Church of Great Saint John the Baptist was built as a Gothic style fort-church probably in the end of 13th century but before 1330's. It is a typical Central-Estonian church with three naves. There is a rectangular east choir and tetragonal west tower. The portals of the church are remarkable. During the wars the pillars and arches of the church were destroyed. Supposedly, the church had round pillars. The wooden ceilings were built when the church was reconstructed.
Late baroque organ prospect (by Johann Andreas Stein, 1804) covers the organ made by the Kriisa brothers in 1937. The altar wall dates back to 1870 and was created by Johann Gottfried Mühlenhausen. The altar painting of church is “Jesus Christ on the Cross”. There is a monument of Hans Heinrich von Fersen, a memorial plaque for Alexander von Fersen, and a unique cross from 1598, one of the oldest in Estonia, in that church.
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.