Bonilla de la Sierra castle has three wall sections and three turrets of different styles and origins. The main par of the castle was formed by the Tower of Homage, of the 14th century, it has matacanes and round arches, and under the tower is the main yard and the rooms. The castle contains 14th-century paintings.
It was the resting place of the prelates of the Ávila bishopric, and held important episcopal synods, as the one in 1384. Bishop Sancho Dávila had a wall built around the village in the 14th 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.