An archaeological investigation was undertaken during the restructuring of the building situated in Via Borromei 5. The area was already noted due to the discovery of archaeological remains on the site between 1950 and 1972. The structures that came to light during the latest investigation had already been partially recorded and then re-buried in 1957 when the building was first put up. Five settlement phases have been identified in the SW area, whilst in the NW area it was only possible to identify the structures belonging to the Imperial palace. The earliest occupation (phase I) in the SW area is attested by post holes and two trenches, probably the remains of a wooden structure and a drainage channel. In phase II the area was cleared and a new building put up, of which two "layered foundations" remain, that is, trenches filled with alternate layers of pressed loam and gravel. In phase III a half-sunk, rectangular structure was built, probably a tank which emptied via a small tile drain. Following the demolition of the structures from this phase a new room was built in phase IV, with "dry-stone" pebble walls which survive at foundation level. During phase V the whole area was occupied by an imposing building constructed on foundations of river pebbles bonded with mortar and brick and mortar walls. In the NW area this phase is attested by the foundations of two or perhaps three adjoining rooms; the building technique is the same as that seen in the SW area. These structures can be attributed to the Imperial palace which occupied the entire western sector of the Roman city with a series of residential, reception and administrative rooms. The structures that came to light have been presented to the public in situ. (Anna Ceresa Mori)