The cryptoporticus is a Gallo-Roman construction that probably dates from the 3C AD. It is actually a semi-underground gallery.
Built below the ancient forum, which was the centre of any Roman town, it was originally rectangular in shape, measuring around a hundred metres by sixty and open on one of its long sides.
All that remains now is the eastern gallery, which is remarkably well-preserved - a rare occurrence in Gaul.
As a listed historic monument, it is now used for temporary exhibitions: this summer, from 2 to 30 June, "La Part Invisible" is an exhibition of puppeteer's objects put on by the Compagnie Pseudonymo.