Numantia was an ancient Celtiberian settlement. It was an Iron Age hill fort, which controlled a crossing of the river Duero.
Numantia is famous for its role in the Celtiberian Wars. In the year 153 BC Numantia experienced its first serious conflict with Rome. After 20 years of hostilities, in the year 133 BC the Roman Senate gave Scipio Aemilianus Africanus the task of destroying Numantia. He laid siege to the city, erecting a nine kilometre fence supported by towers, moats, impaling rods and so on. After 13 months of siege, the Numantians decided to burn the city and die free rather than live and be slaves.
After the destruction, there are remains of occupation in the 1st century BC, with a regular street plan but without great public buildings. Its decay starts in the 3rd century, but with Roman remains still from the 4th century. Later remains from the 6th century hint of a Visigoth occupation.
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.