New data useful for the reconstruction of the ancient urban landscape in the Trastervere quarter of Rome emerged from the collaboration between the Faculty of Engineering (Department of Geodesia and Geomatica, Prof. Mattia Givanni Crespi), the Faculty of Arts (chair of Archaeology and Greek and Roman History of Art, Prof. Andrea Carandini) at Romes’ “La Sapienza” University and the Archaeological Superintendency for Rome. The revision of the archaeological investigations undertaken in 1997 by the superintendency in the area between the present via Portuense, via delle Mura Portuensi and via Carcani (ATAC depot) and the results from a project of analyses and reconstruction of Rome’s urban landscapes directed by A. Carandini, provided new information. The terrain was completely disturbed and there were no walled structures in situ to an average depth of 1.50 m below present ground level. This fact may be linked both to the construction of the ATAC depot, to the construction site of the nearby papal walls of Urban VIII, and to the presence of a medieval Jewish cemetery. Below this level and at a depth of circa 6 m, walled structures came to light relating to a complex of horrea datable to the period of Septimius Severus (3rd century A.D.). These commercial buildings preserved the remains of opus spicatum floors and a white and black mosaic. Part of the structures had been restructured from the 4th century A.D. onwards in order to create a bath complex. A large white and black mosaic (circa 100 m2) with scenes of sea creatures, a polychrome geometric mosaic (circa 400 m2), a room (circa 15 m2) with a pool paved with a white and black mosaic and lined with marble slabs and a feature interpreted as a praefurnium were all part of this complex. All walls appeared heavily damaged by later interventions in the area, in particular by the construction of the nearby papal walls of Urban VIII, which reused the ancient brick curtain wall. In 2004 the Department of “Geodesia e Geomatica” of the Faculty of Engineering at “La Sapienza” University undertook a GPS survey of the excavation area (before back filling), in order to geo-reference the site and to plot the precise spatial location of the structures. On the basis of the new data, it appears that some of the fragments of the marble Forma Urbis relating to the Trastevere area may possibly need repositioning, as they do not correspond to the structures found. Furthermore, when observing the 3D model of fragment 34b a hole for a cramp is visible. This may suggest the possible removal of this fragment (and fragment 33a which is attached to it) to a position at the edge rather than its present position. These preliminary observations require further research and clarification is expected to come from further research developments.