During the Republican period, in the second century B.C., the port system of Rome was centered on the maritime ports of Ostia, at the mouth of the Tiber, and Pozzuoli (Puteoli), on the bay of Naples, and on the Emporium, the river port on the left bank of the Tiber at the foot of the Aventine Hills (the modern Rione Testaccio), that soon became the main service center of the city.
The strong demographic growth of Rome during the late Republican and the early Imperial periods (from the first century B.C. to the first century A.D.) and the resulting difficulties to supply the city, highlighted the logistic shortfalls of the port system established in the Republican period: the port of Ostia had a scarce capacity and the port of Pozzuoli was located too far.
This led Emperor Claudius to establish a new maritime port 3 km to the north of Ostia, starting from 42 A.D. This large port of about 200 ha, soon proved to be unsafe in case of storms and often silted up. Less than 50 years later (second century A.D.), Trajan had the port redesigned, with a new inland basin connected to the Claudian port, that became the external basin, and an improved connection with the Tiber through the fossa traiana (currently the canal of Fiumicino). During the same years, Trajan had also the port of Centumcellae (Civitavecchia) built 80 km to the north of Rome.
A huge service complex, the city of Portus, gradually developed in the area surrounding the new port facilities and became the main maritime port of Rome until at least the sixth-seventh centuries A.D.
Pozzuoli and Ostia continued to function even after the construction of Portus and were further developed. In fact, the first was a good port located south of Rome in a very important economic area; the latter was a port located at the mouth of the Tiber and a large administrative and commercial center directly linked to Rome by the Tiber and the Via Ostiense, and to Rome by a canal and the Via Flavia-Severiana. Ostia remained the administrative heart of this system until the fourth century A.D. when, under Emperor Constantine, Portus became an autonomous municipality, which shows its paramount importance as a supply centre of Rome.
The Port of Claudius
The establishment of this huge infrastructure began under Emperor Claudius and was finally inaugurated by Emperor Nero in A.D. 64. Its main purpose was to ensure the safe loading and unloading of goods from the large cargo vessels arriving from across the Mediterranean, and the transshipment of commodities onto the smaller boats (naves caudicariae) that sailed up the river to Rome.
The port basin was partially excavated inland and partially projected into the sea, with two large piers converging to the port entrance to the west. Here, on an artificial island, a lighthouse similar to the famous lighthouse in Alexandria guided the ships to the port entrance. Another entrance was probably located to the north, close to the airport, between the current building of the Museum of the Roman Ships and the airport facilities. The sea, the port of Claudius and the Tiber were interconnected through at least two canals (the fossae, according to an inscription dating back to A.D. 46) and the river-barges could then sail up the river to Rome.
The foundations of the right (or northern) pier are still visible behind the Museum of the Roman Ships, stretching for about 1km to the west, while some inland ancillary buildings on the quay of the port can still be visited today: the Harbour Master’s Office (Capitaneria), a tank and some thermal buildings dating back to a later period (second century A.D.).
The Claudian basin was too large and too much projected into the sea. Therefore, it soon proved to be unsafe, as it was subject to storms and silting. That led, probably between A.D.110 and 117., Emperor Trajan to have the whole port system restructured.
The port of Trajan
The core of the new harbour was the 32ha hexagonal basin, that was built under Emperor Trajan (probably between A.D. 110 and 117), maybe based on the design by the famous architect Apollodorus of Damascus. This hexagonal basin could accommodate 200 large ships at the same time. A canal linked it to the Claudian port and to the Darsena; another canal, the Canale Trasverso, linked the harbour basin to the Tiber, and enabled the ships to sail up to Rome, Ostia and the mouth of the river. Two roads, Via Portuense and Via Flavia-Severina, ran parallel to the canals up to Rome and Ostia.
A series of new big ancillary buildings were built in the surrounding area and along the canals: warehouses, thermae and a temple. In a central area located between the two port basins, Claudius’ and Trajan’s, the so-called Palazzo Imperiale and other associated administrative buildings were erected. In the same area, the Arsenali (probably the shipyards), have recently been discovered.
The warehouses, horrea in Latin, are the main buildings at Portus. Together with the large warehouses of Testaccio in Rome, located behind the river port, they represent the largest service area of the city.
The so-called Grandi Magazzini di Traiano, together with the later complex of Grandi Magazzini di Settimio Severo and the constant enlargement and restoration of these buildings make Portus a key research area in order to understand the construction and working of the storage facilities in Roman times, as they played a vital role for supplying and feeding the population.
The river port of Rome: Emporium and Testaccio
From the second century B.C. onwards, the construction of a new river port on the Tiber was started in the area of Testaccio at the foot of the Aventine Hills. This area was fenced and paved, and equipped with mooring facilities for ships. In order to cope with the water level fluctuations caused by the river floods, the port was progressively enlarged, and its quays were paved with large slabs of travertine and provided with holed stones for safe mooring and unloading of ships during flood periods. In the first century A.D., a new three-storey building was erected behind that complex. It consisted in a double row of large vaulted storerooms along the river-bank, that were illuminated by skylights opening up on the Tiber bank, and by carriage doors on the opposite side. This building was then enlarged with a new structure consisting in a series of rooms closed by a big inclined wall, and other inner spaces with skylight openings to admit day light.
In the second century B.C., the Porticus Aemilia was built behind the port. It was a huge new ancillary building, 487m long and 70m wide, consisting of 52 naves facing the river side. Over time, the commercial district of Rome was developed behind that area, with department stores, services and the Monte Testaccio dumping ground.