It served, along with other Roman colonies in the area, to control the Helvetii who were settled in the area against their will after their defeat at the Battle of Bibracte in 58 BC.
A rectangular grid pattern divided the area of the wall-less city. A monumental center, housing everything needed for the economic, religious and social life of the colony, was established. Only portions of this first forum have been discovered. At its east end was a two-story basilica. Grid-like residential streets radiated out from the center.
Under Tiberius, the forum was expanded and redesigned into a familiar pattern for the provinces. The sacred area was surrounded on three sides by colonnades, which were built on half-sunken Cryptoporticus. Two outbuildings, including most likely the seat of the Curia, flanked the building. A market building (macellum) with a central courtyard around which were the sales rooms, and the baths (tepidarium with geometric shapes and mosaics) were renovated. The forum witnessed further transformations, particularly the establishment of another large building. During the same building phase a large mosaic on the central part of the north portico was built.
The amphitheater, which was discovered in 1996, was probably built in the early 2nd Century AD. Its arena, which was flanked by two prisons and provided with sewers, is about 50 by 36 metres (160 by 118 ft). The ruins of theater, that should have been in the Colonia, have not been discovered.
The residential quarters consisted of modest homes, in addition to some domi with beautiful gardens and pools. The buildings were originally made of wood and clay, but after the mid-1st Century AD were built from masonry. Some villa suburbana stood in the west of the village, while the artisan and merchant quarter, presumably, developed in the southwest. A 10 km (6.2 mi) long aqueduct which ran from the Divonne area to the colony, provided the water supply. Sewage canals, that
