During the 2012 excavations at Trebbio, work was concentrated in the locality of Commenda with the aim of clarifying the characteristics and chronology of the boundary and/or channel structure identified in 2011. Two trenches were opened with a mechanical digger, in one of which the line of the channel was picked up again. The trench was over 12 m long and almost 4 m deep and exposed the channel’s complete width.

Based on what was visible along the sections and on the bottom of the trench it was seen that: – The channel was dug into the sterile alluvial deposits characteristic of the Tiber plain, which are constituted by alternating layers of more or less coarse sands and altered silts; – It presented a residual depth of about 4 m, was on a north-east/south-west alignment and was 3 m wide at the base and about 12 m wide at the top.

The fill was of particular interest, constituted by blackish silt containing scarce fragmentary materials, except for the first 40 cm of plough soil. The lower part of the fill contained fragments of Iron Age pottery that was in phase with the settlement of Trebbio, while the upper part produced fragments of tegulae and imbrices and a Roman coin.

This data indicates that, if as seems likely the channel was created during the Iron Age, it had still not been completely obliterated in the Roman period. The nature and function of this imposing structure are still to be identified. Above all, its relationship with the settlement of Trebbio remains to be determined and therefore whether or not this was a defensive ditch running around it.