Castello della Valle (Fiumefreddo Castle), founded in 1201, was the residence of the noble lords. During the mid-16th-century, the castle was donated to Ferdinando De Alarçon-Mendoza, marquis of the Valle, and took its current name of Castello della Valle. The current appearance dates from that age. The castle was besieged in 1806-1807 by French troops and nearly destroyed. Today it houses several works of local painter Salvatore Fiume.
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.