Aquis Segeste, a 25-hectare Roman spa town, was located near the Loing River, between the territories of the Sénons and Carnutes. Its occupation predates the Roman conquest, but it flourished under the Flavian dynasty (69-96 AD) and reached its peak in the 2nd century. After 275 AD, it declined and was either destroyed or abandoned in the 4th century.
Rediscovered in the 19th century, it was initially mistaken for Vellaunodunum. In 1917, Jacques Soyer correctly identified it using the Tabula Peutingeriana. Major excavations took place between 1963 and 2005, uncovering a sanctuary, baths, a theater, and a city organized around a sacred spring.
Classified as a historical monument in 1986, it remains an important archaeological site.
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.