In autumn 2001 excavations were undertaken near the _Auditorium_ of _Maecenas_, prior to the restructuring of the basement of the building housing the Direzione Centrale dell’Agenzia del Territorio in Lago Leopardi 5. The finds, uncovered immediately below the floor of two rooms, can be identified as part of the structure of the domus discovered in 1877. A _fistula_ found at the time (CIL XV, 7438) permitted the attribution of its ownership to _M. Cornelius Fronto_, a well known teacher of rhetoric and consul in 143A.D., who in the Hadrianic period lived (FRONTO 1.8) in the _Horti Maecenatis_. In the west room a structure emerged with a partially conserved vaulted roof of which the intrados was 1.035m lower than the auditorium’s mosaic pavement which was 45.252m a.s.l. At two different points in time the room was reduced in size by two brick-built dividing walls, one of which was repaired in opus vittatum. Subsequently, a substantial cement structure was built up against the northern most dividing wall. A small amount of cement had been removed along its length and the gap thus created had been carefully filled with building materials embedded within compacted earth. In the east room the earliest structural evidence was represented by a corridor 1.50m wide, with _opus reticulatum_ walls one Roman foot wide, revetted on both sides, plastered on the interior with yellow and red panels arranged in an alternating pattern. The plaster was in phase with the second of the six overlying floors, the earliest lying at 43.777m a.s.l., directly above natural. Two rooms west of the corridor and on the same alignment were perhaps in phase with the third floor level. A second structure in _opus vittatum_, which was inserted after a general obliteration, maintained the same alignment. However, the alignment was modified in the last building phase represented by two substantial parallel foundations flanking the corridor. One of the foundations presented a drainage channel made from re-used bricks and tile.