We should not forget the role of the port of Alexandria during the Roman period, as it closely follows the Ostia complex in importance. The port was built in the Hellenistic period, and we have already described it at the beginning of Chapter 5 (Figure 5.2). A squadron of Roman warships is based at the port, a point of departure for Egyptian wheat bound for Rome (via Pouzzuoli before completion of the port of Trajan). But Alexandria is also an intermediate stop for products coming from Sudan, Arabia, and the extreme Orient. The Romans continue to use and maintain the canal of Necho that we described in Chapter 3. Trajan develops Clysma (Suez) and undertakes repair of the canal.[292] The canal constitutes one of the routes to Arabia, India, and China, without ever really seri­ously challenging the grand ports of the Red Sea (Myos Hormos, on the site called Qoseir on Figure 3.1, and Berenice, formerly Head ofNekheb).

The port of Carthage, the most important of Africa, is also a point of departure for wheat bound for Rome. We have mentioned the wealth of the Roman Cartago earlier, from its refounding by Augustus in 29 BC up until the 7th century AD when it is des­tined to be eclipsed by the modern Tunis. The port has two basins (Figure 6.37), one for military uses and the other for commercial traffic.

It would be difficult to mention all the other Roman Mediterranean ports. Some are excavated into level ground or in natural creeks, like Carthage and Marseille; others are developed in the mouth of watercourses, as is partially the case of the complex of Ostia, often with the same accompanying problems of sediment management. The port of Leptis Magna, the native city of Septimus Severus, is situated in the mouth of the wadi Labda. This emperor develops the port (Figure 6.38) and erects a lighthouse there. As a typical Mediterranean watercourse, the wadi Labda is subject to rapid and violent floods, and these can endanger vessels or cause other significant damage. As we have

Figure 6.37 The port of Carthage Figure 6.38 The port zone of Leptis Magna (after

(after Scarre, 1995). Scarre, 1995).

seen for some other African dams, a flood diversion structure is built upstream on the wadi Labda. A similar scheme is used by the Romans for Seleucid, the port of Antioch (with a 130-m long tunnel, followed by a 700-m long open cut, 6 to 7 m wide).

The Romans are not great canal builders – even though they maintain and use the Necho canal, or canal of two seas, and rename it the canal of Trajan after this emperor’s work on it. There is some fainthearted thought given to the construction of a canal at Corinth, cutting across the isthmus to enable ships to avoid having to sail to the south of Peloponnese. Caesar, Caligula, and Nero are tempted by this project, and initial work is begun.[293] But there is concern that the sea level may be different from one end of the canal to the other,[294] and that the opening of the canal would provoke a catastrophe. Or perhaps it was simply that the economic stakes were not high enough, for Greece is, under the Empire, more of a symbol than a significant economic player. In any case, the canal was not built in Antiquity.

Rome’s food supply depends on the chain of maritime transport of wheat from Numidia and Egypt. For a long time Rome could offer only minimal port facilities to cumber­some and large loaded boats needing to enter the Tiber at Ostia. Mooring there was especially dangerous when the Auster, an ill-reputed west wind today called the Libeccio, blew. Moreover, access by large boats was made problematic by a shoal. Here is how Strabo describes the situation, in about 25 AD:

“This city has no port, owing to the accumulation of the alluvial deposit brought down by the Tiber, which is swelled by numerous rivers; vessels therefore bring to anchor further out, but not without danger; however, gain overcomes every thing, for there is an abundance of lighters in readiness to freight and unfreight the larger ships, before they approach the mouth of the

river, and thus enable them to perform their voyage speedily. Being lightened of a part of their

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cargo, they enter the river and sail up to Rome, a distance of about 190 stadia.”01

Boats coming from Alexandria or Antioch at this time, after fifteen to twenty days at sea (and sometimes twice that long), prefer to unload in the bay of Naples, at Pouzzuoli (Puteoli). Their merchandise then continues on to Rome either by land or sometimes in smaller boats capable of sailing up the Tiber. Navigation between Pouzzuoli and Ostia is dangerous, since the coast is low and lacks shelter, and therefore Rome is often threatened with shortages. Plans to create a true port at Ostia are proposed under Caesar and Augustus; these plans are often subject to long dissertations. But the first attempt to implement such plans must await Claudius, whom we have already seen as a great hydraulic entrepreneur. A 70-hectare basin (700 m by 1,000 m), excavated

behind the shelter of a naturally growing barrier island, becomes a first basin of the port.

Two large jetties are constructed to protect it; the most offshore one is built of large limestone blocks tied together by iron grapples cemented with lead;[286] [287] it is 330 m long and 23 m wide. Beyond this breakwater a ship was sunk and filled with sand to serve as a subfoundation for the construction of a four-story lighthouse. This was the great 100-m long ship that had been used by Caligula to bring from Egypt the obelisk that now is in Rome’s Place de Saint-Pierre:

“Claudius created the port of Ostia, constructing two jetties in circular arcs to the right and left, and in quite deep water, a breakwater to block the entrance; to seat this breakwater more solid­ly, one began by sinking the ship that had brought the great obelisk from Egypt; upon it, one constructed a great number of piles supporting a very high tour, destined, like that of Alexandria, to illuminate with its fire, during the night, the shipping route.”°J

Work on the port of Ostia proceeds from 42 to 54 AD. The project is finished after the death of Claudius and inaugurated by Nero, who associates his name with the achievement, without completely claiming it as his own, in naming itportus Augusti: the port of the Emperor. Two canals are excavated from the Tiber, obviously to connect the port to the river, but perhaps also to protect Rome by facilitating the drainage of flood- waters of the Tiber to the sea.[288] Somewhat later, the base of the lighthouse is joined to the west breakwater; other boats are sunk to facilitate the initial construction.

But the works of Claudius at Ostia remain inadequate to meet the needs of the city of Rome. Wheat from Alexandria continues to be offloaded at Pouzzouli, not Ostia. Moreover, the port at Ostia has a tendency to fill with sand from the alluvia of the Tiber brought through the canal(s) that link the river to the port, and from the littoral currents that sweep the alluvia of the mouth of the Tiber toward the north. Therefore Trajan excavates a second basin of 32 hectares from 100 to 112 AD. The basin is in the shape of a hexagon with sides of 358 m, a depth of 5 m, and linked to the first basin (Figure 6.36). A new lighthouse is built at the entrance of the canal linking the two ports. The canal coming from the Tiber is retraced: it constitutes a second mouth of the river and is called today the Fiumicino. The new port is connected to this canal, but little of the Tiber’s flow and sediment circulate through the port, which therefore minimizes silta – tion. The overall project eventually will support and receive all maritime traffic with goods destined for Rome. The work is completed, still under Trajan, by creation of an artificial port at Civitavecchia (Centumcellae) to the north, and by improvements at Terracino, about halfway between Pouzzouli and Ostia, to provide shelter along this

coast.[289]

The vast complex of ports of Claudius and Trajan, called Portus, is further improved and maintained under Septimus Severus, and then under Constantine. The complex remains active until the 5th century AD, but then suffers from the decrease in Roman population following the fall of the Empire, and progressively decays. In the 5th centu­ry the sea level is thought to have risen sufficiently to submerge the barrier island that protects the port of Claudius from the west. At this time work is done to provide protec­tion for the canal that links the two ports.[290] The blocks of Claudius’ large jetty to the northwest become partially disconnected, since the structure, lacking the protection of rock armor, was vulnerable to wave attack. There is intense alluvial deposition in the outlets of the Tiber, from the 15th century, and the port complex ends up being land­locked. The remains of the port of Claudius are now beneath the international terminal of the Rome airport. Today’s traveler therefore arrives at the same spot as did the ships from Carthage, Tarraco, and Massilia in the first century.[291]