Oeste Towers (Torres de Oeste) is located at the head of the Ría de Arousa. The towers remaining today are the ruins of Castellum Honesti. In the 9th century, King Alfonso III of Leon built the castle as a defense against Viking attacks. The two remaining towers are from this period, and have a pre-Roman style. Pre-Roman ceramics and bronze tools have been discovered at the site.
Two centuries later, King Alfonso V of Leon donates the fortress to the bishopric of Iria-Compostela, held at that moment by bishop Vestruarius. Subsequent bishops Cresconio, Diego Pelaez and Diego Gelmirez undertook the commitment to strengthen the Castle in order to protect the holy site of Santiago de Compostela. The structure of the Castle was defined in the 12th century. At that time, the enclosure of the Castle was formed by seven towers, and it was surrounded by marshes. The Castle has a 12th-century chapel built by Gelmirez to honor the apostle Saint James. The Castellum Honesti began its decline in the 15th 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.