Excavations on the site of Montessoro (Isola del Cantone-Ge) were undertaken as part of a project investigating late antique and medieval archaeology in the territory of the upper Scrivia Valley. The project, set up by Turin University’s Department of Medieval Archaeology, aims to study the population and structures dating to late antiquity, a period of which little is known in this area. The first campaign lasted ten weeks and investigated a terraced area on a hillside overlooking the modern town of Montessoro. The site is close to the castle built in the 14th century by the Spinola family, at a height of 660 m a.s.l., where concentrations of tile and emerging structures dating to between the 4th and 6th century A.D. were documented.

The excavation covered an area of 20 × 15 m and uncovered a series of four buildings from three different construction phases dating from the 4th to 6th century A.D. The archaeological deposit varied in thickness between 30 cm, in the areas most effected by hill-wash, and a maximum of 80cm.

All that remained of the first building were a few segments of foundation wall. The 4th-5th century phase was better documented. It was characterised by a rectangular structure of stone foundations (8.7 × 5.6 m), divided into three small rooms overlying the earlier phase. The finds and particularly careful building technique suggest a privileged rural context and the use of specialised workmen for its construction. At some stage the building was damaged by a fire, attested by a layer of carbonised beams, which caused the collapse of the roof and the abandonment of the structure. The walls were then robbed and this episode can probably be related to the construction of the fourth building, documented in the centre of the terrace and datable to the 5th-6th century A.D.

The archaeological investigation has begun to shed light on a rural hillside settlement in the territory of the municipium of Libarna that was probably closely linked to road network which from Genoa reached the area of present day lower Piedmont and the towns of the Paduan plain.