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.
The Church of St Donatus name refers to Donatus of Zadar, who began construction on this church in the 9th century and ended it on the northeastern part of the Roman forum. It is the largest Pre-Romanesque building in Croatia.
The beginning of the building of the church was placed to the second half of the 8th century, and it is supposed to have been completed in the 9th century. The Zadar bishop and diplomat Donat (8th and 9th centuries) is credited with the building of the church. He led the representations of the Dalmatian cities to Constantinople and Charles the Great, which is why this church bears slight resemblance to Charlemagne's court chapels, especially the one in Aachen, and also to the Basilica of San Vitale in Ravenna. It belongs to the Pre-Romanesque architectural period.
The circular church, formerly domed, is 27 m high and is characterised by simplicity and technical primitivism.