Chateau des Clées is located above the village. Built probably in the 11th century, it guarded the traffic through the Jougne Pass and collected tolls on the pass road. Les Clées is first mentioned in 1134 when Pope Innocent II tried in vain to prohibit the reconstruction of the castle.
The chapel of Les Clées was built before the 14th century and rebuilt in 1738-1740.
In 1444 the Duke Louis I of Savoy commissioned the renovations of the walls. During the Burgundian War, on 22 October 1475, Swiss Confederation troops seized and destroyed the city and castle and killed the castle garrison. Under Bernese rule there were three courts in the Les Clées district, one of which was held in the city. Nevertheless, the city gradually lost importance.
Today Les Clées Castle with the surrounding ruins and village is listed as a Swiss heritage site of national significance.
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.