At the end of 1872 Lanciani discovered the remains of a small but luxurious domus situated a little to the east of the crossroads between via Manin and via Giolitti (at that time via Principessa Margherita). The recovery of an inscribed fistula aquaria of the 3rd century A.D., L(ucius)·Octavius Felix c(larissimus)·v(ir) (CIL XV, 7503) enabled the domus to be attributed to a specific owner, a member of the senatorial class, who could be identified with a well known person who had lived during the Severan period. On the basis of its typology the complex was dated to the beginning of the 4th century A.D. In May 1998, the excavation of a well (P8), in preparation for the “microtunneling” work necessary for the modernization of the sewers below Piazza Cinquecento and surrounding streets, brought to light a room paved in a geometric mosaic with meander patterns which Lanciani had drawn on his plan of the domus when it was first discovered. Between the 9th September 1998 and the 11th January 1999 other rooms belonging to the small domus were uncovered during the modernization of Termini station. These have been integrated into the plan of the complex to the north and north-east, in fact the last structures found fit perfectly with the alignment of the 19th century plan. The typology of the complex, characterized by the presence of multi-apsed rooms in opus vittatum typical of late antique architecture provides strong support for the hypothesis that these structures formed part of the domus owned by the senator Lucius Octavius Felix. (Oberdan Menghi-Manola Pales)