The literary sources provide little information about the town of _Trebiae_, which became a _municipium_ in 90 B.C., governed by a college of _quattuorviri_. In the Augustan period, the town, whose inhabitants probably belonged to the tribe of the _Oufentina_, was included in the _Regio_ _VI_. In the early medieval period the town’s close relationship with the eastern branch of the via Flaminia increased its strategic importance and in about the 7th century it became seat of the gastald of the Lombard Duchy of Spoleto. Structural remains of _Trebiae_ emerged in 1980, during the construction of a railway underpass situated at only 50 m from the church of S. Maria di Pietrarossa. The houses faced onto a road with drains. An enormous cippus of local limestone was found inside one of the houses. Perhaps a statue base, it bore a dedication to Jupiter Optimus Maximus and can be dated to about the 2nd century B.C. In 2005, work on the construction of a public building at 150 m from the church led to the discovery of about 15 burials in stone coffins, datable to between the second half of the 6th century and the mid 7th century A.D. The first season’s excavations (2015) outlined and documented important previously unknown or only partially known topographical aspects of the Roman _municipium_ of _Trebiae_. Work concentrated on two sectors denominated I and II. Two walls were intercepted in sector I, at a right angle to each other, probably relating to a late antique-early medieval phase. At present, their original plan is unknown but they appeared to be associated with an area used for activities involving the reuse of various types of materials, such as metals, glass and marble attested by the presence of waste materials and scraps. In sector II, a well-built wall, probably belonging to a Roman _domus_, was uncovered. It was faced with polychrome wall plaster on both sides and was therefore a dividing wall between two rooms, whose original extension is at present unknown. The rooms were only partially visible, but each had a well-preserved floor. One was constituted by waterproof _opus_ _signinum_, the other was a mosaic decorated with a plait motif of red and black tesserae on a white background that borders a central field whose decoration is not yet visible. The preliminary study of the pottery, glass, and coins indicates that the site was occupied between the 2nd and 7th centuries A.D. A preliminary study of the artefacts has produced a chronological seriation that associates the finds to the various structures identified.

The excavations undertaken during this second campaign defined and documented important previously unknown or only partially known topographical aspects of the Roman _municipium_ of _Trebiae_. Two different sectors were enlarged, Sector I and Sector II. Two different walls, at right angles to each other, were uncovered in sector I and probably relate to a late antique-early medieval phase. The structures, whose complete original layout is unknown at present, seemed to be connected to an area in which various types of materials were recycled, such as metals, glass, and marble, as indicated by the presence of substantial traces of burning, slag and waste products. The type and construction technique of the structures found in sector II indicate they were part of a Roman _domus_. One of the rooms presented a mosaic floor of medium and small pink and black tesserae. The decorative scheme was formed by vegetal and figured motifs alternating with geometric borders. A threshold, framed by a double band of black and pink tesserae, presented a motif with trails of heart-shaped ivy leaves rising out of a central decoration which included two facing _peltae_ of pink tesserae. The mosaic’s central panel presented a more complex decoration with an octagon within a square, bordered by a braid of two continuous threads in pink, white and black tesserae. The space inside the octagon was edged by a second border, with a black and pink running wave motif that delimited the area occupied by the central decoration depicting the Gorgon. The Gorgon’s face, with rather ill-defined features, is formed of black, white, and pink tesserae, while the two wings crowning the head and the snakes surrounding the face are depicted in glass paste tesserae. The very well-preserved floor can be dated to the 3rd century A.D. Given its size and the decorative motif of the mosaic, the room can be interpreted as a small _cubiculum_. Two corridors, with _opus_ _signinum_ floors, must have linked the _cubiculum_ to the other rooms of the _domus_, while a staircase led to an upper floor, whose existence at present is only a hypothesis. The limited dimensions of the rooms and their development suggest that this complex was a house within an urban context, and could not therefore develop over a larger area. The preliminary study of the pottery, glass and coin finds date the site’s occupation to between the 3rd century B.C. and the 7th century A.D. A chronological series has also been created that makes it possible to associate the finds with the various structures identified.

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.

The archaeological investigations undertaken during the fourth excavation campaign continued to expose important topographic aspects of the Roman _municipium_ of _Trebiae_, which 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. The understanding and interpretation of Room G is decidedly uncertain. This large room had a mosaic floor of pink and black tesserae depicting a marine scene with mythological figures, specifically nine large images arranged in a regular fashion on three registers. Depictions of animals such as deer, horse, bull and snake alternate with anthropomorphic figures, all with fish-like bodies; small winged cupids ride some of the animals. The floor is in a moderately good state of preservation and still in the study phase. Therefore, its chronological horizon remains to be defined, as does the room’s use. Although the marine iconography of the mosaic suggests this room was part of a bath complex, the total absence of architectural elements relating to water management seems to exclude this interpretation for the present. The large corridor I was attached to room G. In fact, the corridor walls abutted the structures delimiting the large room with the mosaic floor. A threshold with sockets for a large double door was found at the point of contact between the two complexes. This appears to date to a period immediately after the creation of the mosaic floor in room G. Indeed, the threshold fills the gaps in the mosaic floor, meaning it post-dates the floor’s creation. At a slightly higher level, there was a beaten earth floor that seems to date to the early medieval period. In fact, the floor was in phase with the wall constituting the northern limit of corridor I. There was reused material in the wall; from the base in small blocks belonging to the Roman structure, the wall narrowed, as it got higher. This construction technique is recurrent in the early medieval period. Therefore, in this period the level of the corridor must have risen by a few centimeters with respect to the Roman floor level. Room N is still in the excavation phase and its complete plan remains to be defined. The room is connected to rooms G, H, F and I. It also has a mosaic floor in pink and black tesserae forming a marine scene with mythological figures, specifically two large anthropomorphic figures of a triton and a nereid, framed by two registers of geometric motifs. Part of the mosaic floor remains to be excavated, thus the interpretation of the mosaic’s iconography remains to be completed. Once again, although the marine iconography of the mosaic suggests this room was part of a bath complex, the total absence of architectural elements relating to water management seems to exclude this interpretation for the present. The preliminary study of the pottery, glass, and numismatic finds from the excavations documents occupation of the site between the 3rd century B.C. and the 7th century A.D. The preliminary analyses of the artefacts has made it possible to define a chronological series allowing the finds to be associated with the various structures identified.

The excavations carried out during the fifth season (2019) continued to reveal important previously unknown or only partially known, topographical aspects of the Roman _municipium_ of _Trebiae_. The open area excavations concentrated on sector II. Two new rooms were identified, denominated Room N and Room P. Room N was connected to Rooms G, H, F, and I found during previous campaigns. A preliminary suggestion is that this was a public complex, whose nature remains to be ascertained. The floor was a mosaic of pink and black tesserae with marine scenes and mythological figures. Specifically, two large images of a triton and a nereid, the mythological figure of Scylla and a large horse with a fish-shaped body, all within a border of two rows of alternating geometric motifs. The various images do not seem to have been set out with a narrative intention; rather they seem to have been thought of individually, without any particular link between them. Although the mosaic’s marine iconography suggests the association of the room in question with a bath structure, the total absence of architectural elements strictly connected to water management seems to exclude this hypothesis at the moment. However, it is possible that there was a small nymphaeum in the west wall of the room, as suggested by the presence of a finely decorated apse, characterised by a base with a moulded travertine architrave and lateral jambs with brick half-columns. Room P was adjacent to room N and the two were connected by a small opening with a travertine threshold. Room P had a well-made _opus_ _signinum_ floor that presented signs of some restoration, showing its prolonged use. Three burials in earth graves, of adult and sub-adult individuals, were intercepted up against one of the room’s perimeter walls. Evidently, in its last phase of use, having lost its original function, the room was used for the burial of the last inhabitants of the site, probably in the 5th-6th century A.D. As the research stands, it is difficult to provide a more precise reconstruction or identify with any certainty the use and function of these structures. However, the typology and construction technique of the walls suggest (a preliminary interpretation) they belong to one or more Roman _domus_ within a settlement that was continuously occupied for a long period. The preliminary study of the pottery, glass and coins indicates occupation on the site between the 3rd century B.C. and the 7th century A.D.

The excavations carried out during the 6th campaign (2021) concentrated on sector II, in particular Rooms N and E, O1, O2, O3, O4. Room N was connected to rooms G, H, F and I, which were identified during previous campaigns. The complex that is appearing can be provisionally identified as a public building, the nature of which remains to be ascertained. Room N was paved with a mosaic of pink and black tesserae representing mythological figures in a marine landscape. The presence of a finely decorated apse, characterised by a footing with a moulded travertine architrave and lateral jambs with brick pilasters, also supports this interpretation. Room S was certainly connected to room N. The structure, entirely faced with _opus_ _signinum_, was an above-ground cistern that fed the fountain situated in the apse of the nymphaeum. The situation in rooms E, O1, O2, O3, O4 merits particular attention. These spaces, quadrangular and similar in size, can be interpreted as a row of small rooms. This system was obliterated in antiquity when the large portico, constituted by corridor L2, was extended during restructuring of the _domus_. This hypothesis was confirmed by the discovery of the _ opus_ _spicatum_ floor of room E below the structures of the quadriporticus. The restructuring almost halved the size of several rooms. At present it is difficult to provide a more detailed reconstruction or identify with any certainty the use and function of the structures that emerged. However, the typology and construction of the walls suggests their interpretation as elements belonging to a Roman _domus_ _publica_ situated within a settlement characterised by a long period of occupation. The preliminary study of the ceramics, glass and coins document occupation between the 3rd century B.C. and the 7th century A.D., A chronological seriation has been defined through this analysis of the finds, making it possible to associate them with the various structures identified.