Since 1979, the foundations of the basilica, discovered in 1974, have housed the Roman Museum which conserves and enhances the Roman remains of Nyon and its district.
The basilica closed off the public part of the forum, the monumental centre of the city, on the side facing the lake. It was built between 50 and 80 A.D., replacing an older building, and was a public building which functioned simultaneously as the town hall, the court of justice and the headquarters of the administrative offices.
The political organization of the Colonia Iulia Equestris was that typical of Roman colonies: a local Senate, a legislative assembly (the order of decurions) and magistrates (duumviri and aedils, normally elected annually), with responsibility for the management and administration of the territory.
The order of decurions met in the curia, a semi-circular room discovered in 1995, adjoining the south annex of the basilica.

Model of the forum and the basilica closing off the open side	The discovery of the basilica in 1974