Below the 17th century fill, rooms were uncovered belonging to a palace dating to the Viceregal period. These comprised an entrance hall and rooms distributed on two levels. The eastern frontage of the insula of this period was delimited by the line of the via della Campana, coinciding with the Greek stenopòs of which traces were found in the deepest levels of the excavation.

One of the underground rooms of the palace reused a terrace wall or perimeter wall of Greek date that was still in use in the Roman period. This was a curtain wall of yellow tufa blocks arranged on top of three courses of orthostats, dating to the second half of the 4th century B.C.

The earliest beaten road surface which came to light comprised yellow tufa chippings and off-cuts mixed with loose sand and ash. The terminus ante quem for its dating was provided by the overlying beaten earth surface dating to the 3rd century B.C., in use throughout the 2nd century B.C.

The western limit of the stenopòs is known from the Roman imperial period onwards. Until the 2nd-3rd century A.D. the distance between the opus reticulatum structures on its two sides was 2.40 m. this increased in late antiquity to 3.20 m. The road and associated network of below ground service structures reached full development at the end of the 1st century A.D. when the ground level was raised, levelling the earliest surfaces and providing a rudus for the paving of a sewer built in opus reticulatum. During the same period a number of buildings were constructed at the sides of the road. Use of the road continued during the following centuries with beaten surfaces datable to the 2nd-3rd century A.D. during which period an opus vittatum inspection shaft was built for the earliest sewer. Use of the road was documented for the entire medieval period, until the construction of an opus spicatum road linked to the Viceroy’s palace.