The building time of Château du Hallier is not known precisely. It is recorded in the 15th century in deeds of sale. The castle was sold to Charles de l'Hospital in 1537. In the 18th century, the castle was used as a quarry; the square second floor disappeared. In the 19th century, the castle became a farm. One of the towers housed a potter's kiln until the early 20th century. Today castle is privately owned. It has been listed since 1967 as a monument historique by the French Ministry of Culture.
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.