The status of the Colonia Iulia Equestris required it to have installations in keeping with the standards of the Roman metropolis, in order to ensure the administrative, political, judicial, economic and religious management of the town and its territory.
This was the function of the forum, a monumental construction, comprising several buildings. It was divided into two parts, separated by the town’s main thoroughfare: the area sacra, where official religious ceremonies took place, and the area publica (basilica and porticoes), housing the town’s lay civic activities. It was here that the judicial and civic decisions which governed public life were taken.
A large mosaic depicting a procession of aquatic divinities, discovered in 1932, decorated the floor of one portico in the area publica.

The cryptoportico of the forum

The cryptoportico was a long semi-underground gallery which served as the base on which the three raised porticoes which defined the area sacra of the forum round the temple stood. Apart from its role as an architectonic support, the precise function of this gallery is not known, although it provided both shade and coolness. It was completed around 50 A.D. A statue in Carrera marble, very probably of the Emperor Augustus, was discovered here in 1997.

Model of the forum	Cross-section of the cryptoportico with the portico over it from which the columns on the Esplanade des Marronniers were taken