Prior to construction work a vast area situated between the modern and ancient via Campana was investigated. This revealed a regular stratigraphic sequence indicative of level ground whose characteristics had not changed over time. The sequence was formed by the slow progressive accumulation of five layers which covered the volcanic deposit from the Agnano-Montespina Flegrean eruption, dated by C14 to 2400-2500 B.C.

The first layer, dating from the Middle Ages to the present day, has so far produced a scarce amount of pottery fragments. The second layer, relating to an unidentified Flegrean eruption, produced a discrete amount of pottery datable to the late imperial period. In the eastern part of the building site two pairs of beaten earth kerbs came to light, on the top of which cart tracks were visible. The third layer produced pottery dating to between the end of the 2nd-4th century A.D. together with four bronze coins, one of which dating to 222 A.D. Below the Roman levels was a mid Bronze Age level, with a low concentration of pottery, and a beaten earth road circa 2 m wide, on an east-west alignment. The last occupation level identified was constituted by the remodelled part of the Agnano-Montespina eruption. Within the layer was an earth grave surrounded by a small channel, its tomb group datable to the early Bronze Age. The channel, circa 0.35 m deep, was cut in the eastern part of the trench, by a pit with a truncated-cone section orientated north-west/south-east. It was partially excavated and the fill contained several fragments of early Bronze Age impasto pottery.