Two big semi-circular frontal halls opened up on the two extremes of the Great Hemicycle on same level as the Forum. Both halls were covered with a similar semi-circular dome and had a main entrance crowned by a frame in bricks that had the same curved shape perfected in their façades.
The bigger frontal hall to the north had two lines of windows and the central access door, now filled in, was set inside two flanking semi-circular niches. On the back curved wall sat a balcony divided by a central section. Sections of the impressions made by the marble paving and panelling are conserved here. Pieces were rectangular on the floor and square on the walls and balcony. After the marble flooring had been pillaged, a series of cavities were dug into the floor, the material was used as the foundations of structures placed in the hall, which may include the church of Saint. Abbaciro.
In Roman times, the frontal hall to the south, with it single line of three large windows and lack of internal niches, must have had a similar aspect of its twin structure. Uprights (sustaining stakes for the wooden frame into which cement was poured) are still visible on the back wall and show us that the foundations were laid prior to Trajan. Only in later times, probably during Trajan’s rule, were the impressions left by uprights filled in by bricks thus allowing plaster to be evenly applied. At such time the marble flooring and the wall panelling was also most probably added, of which very little remains.