The structure found during a rescue excavation on a building site was a section of cloaca sloping down from the SSW towards the fosso di Tor Angela, which runs to the north-east of the area. The line of the sewer deviated towards the north-west in order to slow down the flow of water inside it. Examination of the cavity revealed a substantial accumulation of dumped building material, probably belonging to the robbing of the complex of which this infrastructure was a part. This rather loose accumulation mainly comprised tile fragments and, in a lesser percentage, imbrices. Also present was cement masonry rubble, fragments of tubular bricks for heating, dolia, coarse pottery, African amphora and numerous bones of domestic animals. Of particular interest were a section of moulded marble door jamb, a marble slab also moulded on one side – the opposite side was broken – and a brick fragment with a _dolium_ stamp: _[ex f Domit] Dom Sulp / [Paetin et A]pron cos_, dating to 123 A.D. (CIL XV, 549). The robbing layer described overlay a uniform deposit of tiles and imbrices which, as it was resting on the floor level, probably belonged to the covering of the structure. The floor was lined with tiles, the borders facing upwards and adhering to the base of the side wall forming a cordon. There was a substantial deposit of lime on the bottom, at a depth of 2.55 m below the present ground level. The building technique used for the sewer walls was the so-called _opus listatum mixtum_; in correspondence with the sides of the covering the masonry was in well bedded _opus caementicium_. Both had tufa and brick inclusions. It was not possible to exactly define the composition of the _opus listatum_ facing due to the heavy lime concretion on the surfaces. However, single rows of tufelli alternating with return courses of broken tile were visible. The module, measured between the upper faces of the bricks used, was of 21 cm. The building technique of the sewer, in use from the Trajanic and Hadrianic periods, fits well with the _dolium_ stamp of 123 A.D. and the above mentioned architectural element, despite the fact that the latter had no stylistic characteristics that definitely dated it to the first quarter of the 2nd century A.D. The structure probably belonged to a suburban context situated further uphill, perhaps a villa, The area of terracotta fragments, indicated as n.100 on sheet n° 26N of the Carta dell’Agro, probably also related to this context.