Built in the 12th century in mudejar style, the Castilnovo castle is conserved in good condition. It has a rectangular plan, with six round and square towers. It was rebuilt in the 14th - 16th centuries and again between the 19th and the 20th centuries. The present castle is thought to have been built on a previous structure, probably a small fortress. Trapezoid ground plan, with six round and rectangular turrets of brick and masonry. Arched, parted windows. Rectangular turrets, one if which leads inside the building.
Particularly noteworthy is a corner turret reminiscent of another turret in Monteagudo de las Vicarías. The main features of the building are 14th century.The southern section, with its wooden gallery, dates back to 1861, and the present stone yard was built in the 20th century.
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.