The archaeological investigations undertaken during the third excavation campaign continued to expose important topographic aspects of the Roman municipium of Trebiae, that were previously unknown or only partially known. The open area excavations concentrated on sector II.
As the research stands, it is difficult to identify with certainty the exact use and function of the structures that came to light. However, in light of their typology and construction technique, it may be suggested that they were structural elements relating to a Roman domus within a settlement with a long occupation period.

Room A, which had a polychrome mosaic floor, can be interpreted as a small cubiculum. On a monochrome white background, the mosaic presented a small square ‘carpet’ flanked by a rectangular threshold. Small and medium sized pink and black tesserae, together with the white, created an interesting ornamental solution with vegetal and figured motifs alternating with more usual geometric borders. The threshold, bordered by a double band of black and pink tesserae, presented a motif with trails of heart-shaped ivy leaves rising from a central decoration in which two facing peltae were filled in with rose-coloured tesserae. The central ‘carpet’, presented a more complex decoration with an octagon inside a square, all defined by a continuous double plait of pink, white, and black tesserae. A second border highlighted the interior of the octagon, with black waves and a pink band, which enclosed the area occupied by the central figurative decoration depicting the Gorgon. The Gorgon’s face, with rather uncertain lineaments, was defined by black, white, and pink tesserae, with glass paste tesserae used for the two small wings crowning the head and the snakes surrounding the face. The very-well preserved mosaic can be dated to the 3rd century A.D.

The limited dimensions and controlled development of the rooms also suggests the complex was a residential structure in an urban settlement, thus without the space to extend over a larger surface area.

The reading and interpretation of room G is far more uncertain. This large room was characterized by a pink and black mosaic floor showing a marine scene with mythological figures. More specifically, there are nine large images arranged on three different registers. Animals, such as a deer, horse, bull, and snake, alternate with anthropomorphic figures, both with fish-like bodies. Some of the animal figures are ridden by small winged eroti.

The preliminary study of the pottery, glass, and numismatic finds documented occupation of the site between the 3rd century B.C. and the 7th century A.D. This analysis made it possible to define a chronological seriation and thus associate the finds with the different structures identified during the excavation.