Discovery of massive building at Portus

Archaeologists from the University of Southampton and the British School at Rome working at Portus under the direction of Professor Simon Keay, working in conjunction with others from the Cooperativa Parsifal (Rome), have discovered a massive building at the maritime port of Imperial Rome, near Rome’s international airport which they believe may have played a role in shipbuilding centred at the port. The work is part of ongoing collaborative research with Angelo Pellegrino of the Soprintendenza Speciale per i Beni Archaeologici di Roma, Sede di Ostia, led by Dottssa Moretti.

The building is rectangular in form and extended from west to east for a minimum of 145m along the northern side of the Trajanic hexagonal basin, at the heart of the port. Its primary face dates to the Trajanic period (possibly AD 110-117). The main body of the building was articulated around a series of massive brick-faced concrete piers that defined eight parallel bays around 60m long that ran from north to south and opened onto both the Claudian and Trajanic basins.

The current excavations have uncovered a wide vaulted passage that defined the western side of the complex, as well as the most westerly of the bays. They suggest that the individual bays were approx 12m wide and 58m long, that the rectangular piers measured approx 2m x 1.5m, and piers at the southern end measured approx 3m x 1.7m. The finish and sheer size of the latter makes it clear that the principal entrance probably lay to the south and that it comprised a massive arch; it is also clear, however, that could be entered by a substantial opening on its northern side.

This work complements extensive geophysical survey and topographical work carried out in recent years and suggests that the building as a whole comprised around ten of these bays that together would have presented a monumental arched façade onto the Trajanic basin. Their scale is best appreciated when it is realised that the vaulted bay would have originally stood to upwards of around 12m or more: the impact of this best appreciated by looking at the surviving vaulted hall of Trajan’s Markets at Rome (AD 100-110), which has a similar bay with a width of 9.8m which stands to a height of 12m. In terms of layout, the building is without a ready parallel at Portus or Ostia, and its closest parallel is the building traditionally identified as the Porticus Aemilia (190 BC) at the river port of Rome itself, and which has a total length of 487m composed of 50 bays with a length of 60m and width of 8.30m.

The scale, position and uniqueness of the building lead the team to believe that this building played a key role in the construction and repair of ships at Portus. In particular, it is suggested that it may have been used for the construction of ships, and to shelter them in the winter months. It could also have been used for housing the large supplies of wood, canvas and other supplies that would have reached the building by way of the Claudian port and fed through the northern entrances. A mosaic found at a villa on the Via Labicana (a road leading south east of Rome), represents the façade of a building very similar to this one, with a ship clearly visible in each of the bays of an arched façade very similar to the way that the example would have looked. The finishing of the ships themselves would have taken place on a flat area approx 30m wide between the façade of this building and the edge of the Trajanic basin, benefitting the from the comparative calm offered by this sheltered basin. Members of the Archaeological Computing Research Group of the University of Southampton led by Dr Graeme Earl, working closely with members of the Portus Project team, and in consultation with colleagues at the Centre Camille Jullian of the Universite d’Aix-Marseille-CNRS (for ship information), have produced some initial computer-graphic images that help explain how it is currently believed that this building might have looked in antiquity. These images employ procedural modelling technologies such as CityEngine which enable a wide range of alternative interpretations of the building to be produced and examined. The most likely of these are then transferred to software such as 3ds Max, more commonly seen in the production of film and television graphics, to produce visualisations designed to inspire new ideas and to represent the conclusions drawn from the modelling and extensive archaeological analyses.

Shipbuilding activities at Portus have been mentioned in stone inscriptions from the port, and neighbouring Ostia, referring to the guild or corporation (collegium) of the fabri navales portensium or the fabri navales ostiensium, consisting of wealthy freed slaves. It needs to be understood in the context of the Imperial Palace, or Palazzo Imperiale, which have also been the subject of recent excavations by Professor Keay and his team, and which they argue was a key complex at which was centred an imperial official charged with coordinating the movement of ships and cargoes within the port as a whole. The sheltering and repair of ships has also recently been argued for Ostia, although the proposed site was on a much smaller scale than this one.

This discovery has major implications for our understanding of the role of Portus. It is generally assumed that this, and indeed, many of the buildings at Portus were warehouses, and that the port was primarily an area of transshipment. This discovery, however, adds to evidence that it was the focus of other vitally important activities that helped define Portus’ role as the maritime port of Imperial Rome. Our building would have encompassed c. eight concrete vaulted bays whose façade would have dominated the whole of this side of the hexagonal basin. In addition to suggesting that the port was the site of the shipyards of Imperial Rome during the early to later 2nd century AD, it also raises the possibility that ships from the imperial fleet headquarters at Misenum (Miseno), on the Bay of Naples, might have been sheltered or repaired here. If so then it becomes easier to accept the idea that Portus may have had some kind of naval role to complement that of the great naval base at Misenum to the south.

Inscriptions mentioning sailors from the Misenum fleet have been found at the site as well as at Rome itself. It needs to be stressed, however, that there is as yet no evidence for ship ramps that one might expect to have witnessed the launch of ships into the Trajanic basin: if they existed they would lie beneath the early 20th century embankment that currently runs around the outside of the hexagonal basin. It is thus difficult to know whether military ships or merchant ships might have been repaired or launched here. However, the length and width of the bay were sufficient for it to have housed a large merchant ship, of the scale of the well-known Madrague des Giens, an earlier wreck, but which was approx 10m wide by 40m long. If the shipshed on the Via Labicana mosaic was a representation of the Portus shipyard building, and the ships represented were military, then it is possible that the building might have housed military ships.

It is hoped that a new phase of excavations taking place during September and October 2011 will provide an answer to this question. They will also help shed light on the later history of this building, which sees the function of this particular bay transformed with the construction of a series of adjacent rooms within it on a new east-west alignment in the later 2nd/early 3rd centuries AD, the conversion of these into granaries in the later 5th century AD, and their systematic demolition as a defensive measure during wars between the Byzantines and Ostrogoths in the early to mid 6th centuries AD.

Photographs from the Portus Project are available on our Flickr site. The Portus Project Photostream is online. You can also see a Portus Project Slideshow.