Neither the origins nor the date of construction of San Romualdo Castle is certain, although historians are fairly sure that this castle dates back to medieval times. Built in the Mudéjar style, it was first mentioned in 1268. It is thought to have been used as both convent and fortress.
The castle was officially declared as a historic monument by the Spanish authorities in 1931 and is easily located near the town centre, half way between the town hall and the Zuazo Bridge.
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.