Inextricably linked with the history of the city of Rome is the history of its port, Ostia (literally translated as "the mouth"), located 22 kilometers downstream where the Tiber River empties into the Mediterranean Sea. Since Rome depended on importing overseas food for its survival (but the river up to Rome was not navigable by large ships), there was a clear need for a port where goods could be unloaded, stored, and then transferred to small ships or barges for the journey upriver to Rome. Unfortunately, the mouth of the Tiber was ill suited for such a port. The region was unhealthy, characterized by swamps and low-lying areas that bred swarms of diseasecarrying insects. Additionally, the Tiber was prone to silting, and there was no natural protected inlet or harbor where ships could dock and be safe from storms. These drawbacks caused the development of Ostia to lag behind the growth of Rome; however, the sheer scale of the imports necessary to support the capital eventually ensured that Ostia was forced to assume a major role as a port and also made it the focus of gigantic building projects intended to rectify its shortcomings.
According to Roman legend, the king Ancus Marcius first established a city near the mouth of the Tiber to facilitate the mining of salt beds. Whether or not this town was on the same site as Ostia, or even whether it existed at all, is impossible to tell. The first firmly historical Roman settlement at the mouth of the Tiber dates to the fourth century bc, when a military fort, a castrum, was established to guard the entrance of the river
Figure 73.1 Map of Ostia. (Reprinted from Frank Sear: Roman Architecture. Copyright 1982 by Frank Sear. Used by permission of the publisher, Cornell University Press.)
Against sea raiders. This camp was fairly small and was laid out in a standard rectangular shape around the intersection of two main streets, the cardo and the deciimanus. A wall protected the castnim, the total enclosed area of which was only about 2.4 hectares. A civilian settlement subsequently grew up alongside the castnim, centered to the west of it.
As the city of Rome grew in population and as it became necessary to import food supplies, Ostia was forced to play a role in this transportation system. By at least the time of the Second Punic War, grain from Sardinia was passing through Ostia on its way to Rome. Ships either would have had to be small enough to be able to travel upriver directly to Rome or else had to anchor just offshore or in the mouth of the river where their cargoes were transferred to smaller lighters and barges for the trip upriver. This was a dangerous anchorage, and there were not really facilities to accommodate large ships, so much of the grain supply was alternately routed to the port of Puteoli on the Bay of Naples to the south. Puteoli had a well-protected harbor where large ships could tie up to the quays directly; thus, many of the largest grain freighters, including the grain fleets from Alexandria, preferred to dock at Puteoli rather than at Ostia. While the harbor facilities at Puteoli were superior, using this port meant that the cargoes then had to be carried overland for the final stretch of their journey to Rome, a much more cumbersome and expensive process than water transport.
Despite these factors, much traffic came through Ostia and the city steadily grew. In the first century bc, a new set of walls was constructed, which enclosed some 65 hectares, clearly demonstrating how much the city had expanded since its foundation as a castnim. The old castnim had by now been completely absorbed by the city and had become its forum space. Apartment buildings sprouted up to house the population of dock-workers and shipbuilders, and numerous warehouses appeared scattered throughout the city to store the vast quantities of goods arriving from overseas. Under Augustus, a number of important Ostian landmarks were constructed, including the theatre and its surrounding piazza, which were erected by Augustus's friend and helper, Agrippa. Under Tiberius, a large Temple to Rome and Augustus was built, as well as public baths and an aqueduct. During the first century of the empire, a squad of vigiles (firefighters) was established at Ostia; also during this time, Ostia gained a more defined harbor area. Just inside the mouth of the river, a rectangular harbor approximately 100 meters deep and 160 meters wide was excavated from the riverbank. Along the east side of this harbor was a huge platform with a vaulted substructure that served as a ship shed. Centered on top of this structure was a large temple oriented toward the sea. Around the harbor were more horrea, or warehouses.
Beginning under the reign of Claudius, Ostia experienced a boom time that would last for the next 100 years. While the existing harbor facilitated the loading and unloading of ships, there was still no anchorage safe from storms, and more dock space was needed for the hundreds of freighters coming to Ostia. In ad 42, the emperor Claudius tackled this problem and began to excavate substantial harbor works at a site approximately four kilometers north of Ostia. He dug out of the coastline a huge artificial harbor some 1,000 meters in diameter that was connected to the river and to Ostia by canals. This harbor was enclosed by two long, artificial moles constructed of travertine blocks and concrete. Atop one of these was erected a lighthouse that used as its foundation the giant ship that had been built to transport the obelisk of Heliopolis from Egypt to Rome under the reign of Caligula. This ship, over 100 meters long, was filled with concrete and sunk to form the lighthouse's base. This new harbor, known as Portus, was at this point not regarded as a separate town but rather as an extension of Ostia; thus, both sites were administered by the existing bureaucracy at Ostia. Portus must have provided desperately needed docking space to alleviate the crowding at Ostia. However, despite all the effort and expense that went into its construction, the problem of safety from storms was not solved; in ad 62 a storm sunk over 200 ships within the new harbor. There also seems to have been an attempt to raise the ground level of the area, probably to render it safer from Tiber floods. After the devastation of the Great Fire of ad 64 at Rome, Nero ordered that all grain barges bringing wheat from Ostia to Rome load up with rubble for the return trip to Ostia, where the debris was to be used to fill in the swampy lowlands.
Rome at last got a first-rate harbor when the emperor Trajan rebuilt Portus and added an inner harbor where ships could be completely safe. This inner harbor was a giant hexagon 700 meters across, lined with well-made quays and mooring points. The modern airport that serves Rome was built partially over Portus, and the outline of Trajan's hexagon is still quite visible to tourists landing in a plane. In the second century ad, there was much construction at Ostia and Portus, with many large insulae (apartment buildings) and horrea being built or rebuilt, as well as new bath facilities and a Temple to Jupiter. This phase of building included the widespread use of solid brick as a construction material in addition to some brick-faced concrete.
By the third century ad, a decline in the population of Rome, coupled with problems with the river mouth silting up, caused the end of Ostia's growth. As the volume of maritime traffic declined and the facilities at Portus were sufficient to carry the reduced load, Ostia began to lose its bustling industrial nature. In the late third century ad, many commercial areas and buildings seem to have no longer been heavily used or were turned to alternate purposes. Interestingly, it is from this period that many of the large private homes or villas appear to date, suggesting that Ostia was being transformed from a predominantly commercial city into more of a seaside resort for wealthy vacationers from Rome. Under Constantine, Portus was administratively split off from Ostia and became its own city.
Figure 13.2 Mode! of Trajan's harbor, [ts distinctive hexagonal shape is still visible today as a depression in the ground.
In the fourth century ad and following, Ostia rapidly dwindled. With its purpose as Rome's port gone, the unhealthy, swampy nature of the site once again became a dominant factor, and Ostia was essentially abandoned, At its height, Ostia's population may have been as high as 50,000, but by the early Middle Ages it had become a ghost town, and because of its malarial nature, the ancient city was never really resettled or built over. This has proven to be of great benefit to historians and archaeologists since ancient Ostia is now one of the best-preserved Roman sites. Because of its extensive rebuilding in the first and second centuries ad, followed by its rapid decline, Ostia is also our best guide to what imperial Rome would have looked like at its height, especially in terms of residential and commercial structures.
Although Ostia suffered the same looting for statues, mosaics, and other works of art as most ancient cities from the Renaissance to the present, because it was never built over, the ruins of the city's buildings remained relatively untouched from the Renaissance to the present. In the late nineteenth century, more systematic and scholarly excavations began to uncover some of these structures, and this work continued gradually until the 1930s. As part of Mussolini's attempt to link his own government with the achievements of ancient Rome, interest in the site intensified, and from 1938 to 1942, extensive digging was carried out, which uncovered large sections of the city. While these excavations more than doubled the exposed areas of the city, the speed with which they were undertaken meant that the records of the digging were spotty and that much poten-
Tially useful data was lost. The regions revealed by the 1938-42 excavations remained the known parts of the city and the focal point of Ostian studies throughout most of the rest of the twentieth century. In the last few years, a new survey project using various sophisticated technologies to analyze what lies beneath the unexcavated areas has been undertaken, and promises to add substantially to our understanding of the city. Preliminary results suggest that the currently excavated regions represent only about one third of the original total area of the city, and this project has already identified the remains of many previously unknown but important urban structures. For example, the number of known horrea, or warehouses, has more than doubled. Once the data from this survey have been analyzed, the history of Ostia may need to be revised to take into account this new information.
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