Colombier Castle was built in the 11th or 12th century as a fortified tower over the ruins of the Roman villa. It expanded in the 13th Century and by the 16th century had reached its present appearance.
One of the largest Roman era villas in Switzerland was excavated from under the castle in 1840-42 by Frédéric Dubois de Montperreux. It was built in multiple stages between the 1st and 3rd centuries AD into a palatial mansion with a peristyle, at least two baths with mosaics and frescoes and terraced gardens.
In 1806, Colombier Castle was converted into a military hospital. Starting in 1824 it was used by the Federal militias as a parade ground and was converted into a barracks and given an expanded arsenal. In 1877 it became the official barracks of the 2. Division, which later became Field Division 2. In 2003, the Army XXI reforms dissolved the Division and in 2004 the barracks became an infantry training center.
References: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.