As a five-year (2017-2021) project run by the École française de Rome entitled“Ostie-Portus, hub de l’empire romain”, the study of the north-south wharf at Portus came out of a wider programme researching the port of Claudius, undertaken through the study, just completed, of the so-called Magazzini Traianei di Portus. Probably built as a direct continuation of the colonnade of the Portico of Claudius, which flanked the west side of this vast warehouse complex, the north-south wharf forms the back-bone of the port system built by Claudius, and forms the link with the later Trajanic reorganisation. One of this new study’s main objectives will be to find evidence of a construction connection between the Portico of Claudius and the wharf, which together must have created a majestic seaward facade, several hundred metres long, leading into the centre of the port system. At present, the wharf structures are largely covered by vegetation. However, the entire length of the monument’s “donkey-back” outline is perceptible between the end of the Portico of Claudius, at the north-western corner of the so-called Magazzini Traianei, and the modern so-called Casaletto, situated 350 m further north, at the feet of the piers supporting the over head road (via dell’Aeroporto di Fiumicino) that are built on the wharf structures themselves. The first investigations, begun in October 2017, looked at the terminal part of the wharf, around the Casaletto, with the opening of two trenches, which, in substance, were limited to cleaning the surface of almost 350 m2 of structures. The aim of this first campaign was to recognise the technical characteristics of the wharf construction, identifying possible differences in the construction phases. Topographical surveys were undertaken, which determined the exact position of the wharf’s structural remains within the ancient harbour basin and precisely positioned them in relation to the orientation of the large warehouse structure. This campaign showed that in its original Claudian phase the wharf was smaller than foreseen and that the part investigated in 2017 corresponded with two later extensions to the wharf. A first extension, about 40-45 m long by 6 m wide dated to the Severan period. In a later phase, a new structure was built abutting the seaward side of the first extension, which doubled the width of the Severan wharf (total width 14 m) and extended the length for s further 60-65 m towards the north. The terminal part of the latter extension of foundations, still visible behind the Casaletto, was characterised by the reuse of large marble fragments in the foundations to consolidate this zone, which probably had to support a particularly large architectural structure, for example a monumental warning lantern. The next campaign will be dedicated to the study of the original wharf, in particular the final section abutted by the two extensions. The other campaigns in the five-year programme will investigate the area of contact between the wharf and the Portico of Claudius, in which several structures associated with a small bath complex, probably of late date, are visible.

This was the second season of excavations on the north-south mole at Portus, part of the five-year project (2017-2021) “Ostie-Portus: Hub de l’empire romain” run by the École française de Rome. The mole, c. 300 m long on a north-south alignment, is situated on the western edge of the archaeological park. The 2018 investigations were dedicated to the study of the zone where the north end of the Claudian mole joined its first extension dating to the Severan period, which was investigated last year (Fig. 1). Therefore, an excavation area of c. 200 m2 was opened just south of last year’s area. The new area was divided into four trenches: two situated at the foot of the mole on the east side; one on the top and one for the surface cleaning of other structures on the east front. The aim was to observe the construction technique of the Claudian mole in greater detail and to gain an understanding of how the Severan extension was attached to it. As regards the structure, there was a general reorganisation of the mole during the Severan period. In addition to the extension of c. 50 m to the north (Fig. 2), identified in 2017, this season’s excavations have shown that the walls of the Claudian structure that are visible today correspond with a Severan reconstruction. The latter is easily identifiable by the systematic use of typical thin red _bipedales_. In the same way, late antique additions can be seen in the structural sequence, both in the upper part and against the east front of the Claudian mole, which thus results as incorporated into the subsequent phases (Fig. 3). As regards the original mole of Claudian date, it is probable that it was built using the same technique as that used for the foundations of the so-called Trajanic Warehouses, involving the use of _opus_ _caementicium_ in formwork for the lower part and the use of _opus_ _reticulatum_ for the standing parts guaranteeing that the mole stood above the water. Therefore, the Severan constructions used two different techniques: pouring cement on top of the earlier structures of the Claudian mole and then using the classical technique, beyond the latter’s north end, of _catenae_, _stipites_, and _destinae_. The latter is typical of structures standing in water, and does not appear in any other part of the Claudian mole that developed in connection with the portico of the so-called Trajanic Warehouses, situated 200 m to the south. In particular, the structural analysis showed how the first few metres of the Severan extension were without timber framework. In fact, a “platform” formed of mixed materials bonded with a very strong pozzolana mortar, was poured directly against the north wall of the original mole, thus creating a solid element on which to attach, later, the timber framework for the new mole. As shown by the 2017 excavations, the mole’s structures underwent continuous transformations until the late antique period. If, on the one hand the late antique interventions substantially limit the possibility of finding the Claudian structures, on the other they show the mole’s long period of use, and overall the long life of the port site. The material finds are particularly important for the definition of this picture, as they are for the most part late antique ceramics.