The resolutely contemporary building was inaugurated on the 26th of June 1990. Its construction, above the archaeological remains, was begun from a central core lying on four concrete posts.

Traffic around this central core is achieved by means of sloping spiral ramps suspended from the building's steel structure. These ramps create the permanent exhibition space and allow visitors (including wheelchairs) to descend into the crypt, the real heart of the museum.

With a total floor space of 2400m2, the archaeological museum comprises three levels. Access to the first floor is via a gently-sloping ramp. On this level, a belvedere gives a panoramic view across the Roman site. Then the visitor is invited to make their way to the ground floor via an internal ramp and, from there, to the crypt in the basement.

In Argentomagus, the prehistoric displays are presented chronologically whilst those of the Gallo-Roman period are displayed thematically. Reconstructions, films, videos, audiovisual animations and models, all designed for a lay audience, accompany the exhibits.