Ostia - Decline, late antiquity, and Middle Ages
The decline of Ostia
After the Severan dynasty there was political chaos in Rome. The reign of many Emperors was now ended by revolt or assassination after a few months or years. The economy collapsed. In Ostia building activity was minimal, and the number of inscriptions dropped dramatically. The population shrunk. In the second half of the third and in the fourth century Ostia and Portus were struck by earthquakes and tsunamis. The first seismic events seem to have taken place in 238 AD (in Portus corpses were found below collapsed masonry), other evidence points to the reign of Probus (276-282 AD; several buildings collapsed), and an earthquake documented in Rome in 346 AD may also have damaged the harbours. Often the ruins were not even cleared. Apparently it was not economical to rebuild them. The warehouses in Ostia were not used anymore, contrary to those in Portus. Eventually the fire-brigade left Ostia. And other tensions were building up: in 269 AD eighteen Christians were executed in front of the theatre, on the street.
The local calendar was maintained until at least 175 AD. The last duovir is documented in 251 AD. Aurelian (270-275 AD), says a late historian, "began to construct a Forum, named after himself, in Ostia on the sea, in the place where later the public magistrates' office was built". Imperial generosity focused on the area near the beach, not on the harbour district along the Tiber. Rome now once more took over the control of Ostia. The city came under the authority of the prefect of the grain-supply (praefectus annonae), who was curator of the harbours.
Late antiquity
In 308/309 AD Maxentius opened a mint in Ostia, but this was a short-lived event. The mint was closed in 313 AD. Constantine made a small part of Portus an independent "city", called Civitas Flavia Constantiniana. But the Alexandrian grain-fleet now took the Egyptian grain to Constantinople; Rome was supplied by North Africa. On the other hand, Constantine donated a Christian basilica to Ostia, perhaps identified in the 1990's through geophysical research. And from 336 AD the bishop of Ostia consecrated the new pope. There are indications that the economy of Ostia was recovering somewhat in the fourth century. Many inscriptions from this period have been preserved and the building activity increased, albeit with reused material. The marble slabs of the fasti were used as thresholds, and funerary inscriptions can be seen in the pavement of houses.
A room in a late-antique house with a statue of Cupid and Psyche. Photo: Parco Archeologico di Ostia Antica. But Ostia was from now on primarily a pleasant living environment. Many expensive habitations (domus) were installed in older buildings, from the later third until the first quarter of the fifth century. Unfortunately it is not clear who were the inhabitants. The houses may have been used by wealthy people from Rome, as a second house near the beach, or by merchants whose interests lay in Portus. In 387 AD Saint Augustine stayed in Ostia with his mother Monica, who died there: "... she and I stood alone, leaning in a certain window, from which the garden of the house we occupied at Ostia could be seen; at which place, removed from the crowd, we were resting ourselves for the voyage [to North Africa], after the fatigues of a long journey". The area along the Tiber had been abandoned, and here rubble was dumped on the streets, to create a barrier, in places four metres high, to protect the southern part of the city from Tiber flooding. An inscription from the late fourth century mentions the transfer of a statue "from sordid places" (ex sordentibus locis) to the Forum.
In the early fifth century Ostia was no more than an average Italian city, contrary to Portus, that remained important as harbour: from now on the praefectus annonae governed Portus, but not Ostia. In 409 AD Alaric with Goths captured Portus, but ignored Ostia. In 455 AD Gaeseric and the Vandals sacked Portus. An inscription informs us that they burned the church of Saint Hippolytus on the Isola Sacra. Perhaps they also plundered Ostia. At the end of the fifth century the Ostian aqueduct stopped functioning. Many Ostians now lived and were buried in ruins. At the same time Portus was a thriving harbour. In 537 AD Vitigis and the Goths laid siege to Portus. The Roman general Belisarius defended Portus and Ostia. The last inhabitants of Roman Ostia had retreated to the theatre, that was turned into a little fortress.
The Middle Ages
In the early ninth century Ostia was captured by the Saracens. In response pope Gregory IV (827-844) built a new town to the east of Roman Ostia: Gregoriopolis, at the spot of the modern village Ostia Antica. Here the church of Saint Aurea, a martyr from the third century AD, had been built. In the middle of the ninth century the Saracens returned, and took the fortress and Portus. Pope Nicholas I (858-867) reinforced the town. For a long time there had been marshes to the east of Ostia, in which rubble from Rome had been dumped after the great fire under Nero, in 64 AD. The marshes now became a lake, and the area was infested by malaria. As late as 1162 AD the people of Gregoriopolis visited a little chapel near the theatre, where Christians had been executed centuries ago, in a procession along the Via Ostiensis and Decumanus Maximus. But by now the tombs and buildings flanking the road were half-buried ruins.