The Monastery of Santa María de Mezonzo is a Romanesque style former monastery. Although it probably dates back to the time of the Kingdom of the Suebi, the current monastery was founded as a double convent by Abbot Reterico. According to Antonio López Ferreiro, the monastery was donated to the Asturian-Galician king Alfonso III el Magno in 870. Justo Pérez de Urbel, after comparing the names of the confirmatory of several documents related to the monastery, thinks that the correct date is the one given by Hinojosa, that is, the year 930.
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.