The place dominated by the Ucero castle has been inhabited since prehistoric times. The castle is built on the site of an ancient Celtiberian castro. The site was first time mentioned in 1157 when Alfonso VII located the village of Sotos the Suso between Uxama and Ucero and there are documents that indicate that the castle already existed in the 13th century. It is estimated that the important hermit of San Juan de Otero, nowadays destroyed, was ubicated near San Bartolomé, which was a Templarian chapel.
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.