Archaeological investigations were carried out during the construction of an underground car park in Piazza Baronio. Below the modern levels a layer of loam was revealed, rich in archaeological material (pottery, mosaic tesserae, animal bones, brick, mortar, glass, painted wall plaster). This layer was present across the entire construction site. Below, lay part of a wall in opus incertum, on a N-S axis. It was 0.50m wide, standing to a height of 1.30m and was visible for a length of 5.80m. Built directly up against the terrain, it seems to have functioned as a retaining wall for the housing of a water channel. In fact, piping, formed by a series of terracotta tubes inserted one into another and bonded with mortar, was uncovered on the same axis as the wall. A fragment of Dressel 1 amphora handle provides a terminus post quem of the mid 2nd century B.C. for the structure (a date supported by the opus incertum). The continuation of construction work on the side of the site near the State Mint, on the corner with via C. Siconio, brought to light several fragments of terracotta tubes similar to those found near the wall in the adjoining car park. Fragments of common ware pottery and small, squared stone blocks from the construction of the opus incertum wall were also recovered. These remains may be a continuation of the opus incertum wall, disturbed at this point during the construction of modern sewers. A well, 0.77m wide, with footholes and a cuniculus were also found, dug into the tufa bed-rock. The evidence suggests these structures were part of a system for water collection and distribution in this area from the 2nd century B.C. onwards. (Patrizia Campagna, Silvia Sangiorgi)