Château de Houlbec-près-le-Gros-Theil was originally a square castle with rounded corner towers. It was built in the Middle Ages and conquered by English in 1418 (Hundred Years' War) and by Catholic League in 1588 (during the Wars of Religion). The castle was rebuilt in 1786 and heavily damaged by fire in 1910. Today the château is abandoned but two towers and other signicant ruins still remain.
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.