The excavations completely exposed room III and part of the portico in front, separated by a low step. The removal of the alluvial layers revealed both the collapses and fragments of architectural decoration, and part of the marble wall facing belonging to the vast hall.

The quadrangular hall (6 × 14 m) had an entrance to the south, probably flanked by two pillars or columns, attested by in situ plinths. The walls were in opus reticulatum, which to the north rested on blocks of yellow tufa opus quadratum, left over from the first monumental border around the forum. On the western side of the latter, was a large opening flanked by pillars, a link between the forum area and the buildings to the north. Therefore, the buildings dating to the mid 3rd century B.C. were transformed and adapted during the 1st century B.C. In fact, the blocking of the opening and the overall definition of the hall that was paved in opus signinum, visible below the make ups for the later flooring date to this period.

The construction technique was similar to that used for the sacellae on the western side of the northern forum, confirming the coherence of the project that came to be defined in the final years of the 1st century B.C.

In a later period, the walls were decorated with aedicolae the largest, at the centre of the main wall, paved with coloured marble. These housed statues as attested by the plinth exposed in the eastern aedicola . The rich decorative scheme identifies this space as an imperial cult building dating to between the end of the 1st century and the first decades of the 2nd century A.D.