One of ancient Capua’s most outstanding public buildings was the cryptoporticus (later a monastery and the prison of St. Francis) which certainly stood in the forum area. Trenches dug prior to the work on the installation of the Faculty of Letters and Philosophy of the Second University of Naples provided further information about this structure. It emerged that, whilst in the interior no clear traces were found of the original construction, on the exterior, in correspondence with the small towers added in about 1819, a facing of large size opus reticulatum was uncovered. This would seem to confirm the dating of the cryptoporticus to the Caesarian period. The discovery of the substantial remains of a perfectly preserved basalt paving on the north and east sides attests that the structure stood completely above ground, probably surrounded by a square, perhaps the forum itself.