The investigations, undertaken as part of the work to modernize Line A of the underground railway, involved the southern area of the piazza and provided new data about the ancient topography of the Esquiline hill. The excavation covered circa 160 m2 and revealed part of a residential complex, built over levels belonging to the Esquiline necropolis, covered and reclaimed by order of _Maecenas_. This was one of the pavilions that formed the _Horti Lamiani_, laid out in the V regio ( _Esquiliae_ ) by the _gens Aelia_ during the Augustan period. It was possible to partially reconstruct the development of the pavilion’s plan from the early Imperial to the Severan period. The building was restructured and its spaces re-organised many times, events which can probably be attributed to the frequent changes in ownership. By exploiting the conformation of the southern slopes of the Esquiline the rooms were created on terraces supported by substantial sustaining walls. A gradual extension of rooms both towards the east and west was observed. Although 19th century digging has obliterated and damaged the walls of these structures much evidence remainsregarding the sequence of the floors. These are mosaics and pavements in _opus sectile_ all with geometric motifs. (Salvo Barrano – Mariateresa Martines)