A brief overview of Ostia, to be used as a very first introduction.


Ostia is Latin for "mouth", the mouth of the river Tiber. In the Republican period the river entrance was used as harbour, and in the Imperial period two huge harbour basins were added to the north, near Leonardo da Vinci airport. The harbour district was called Portus, Latin for "harbour".

The ancient harbours seen from a plane. Photo: Paolo Fusco (click on the image to enlarge).

The ancient Roman city of Ostia was in antiquity situated at the mouth of the river Tiber, some 30 kilometres to the west of Rome, and on the Mediterranean sea. However, the shoreline moved seawards from the Middle Ages until the 19th century, due to the deposition of sediments transported by the Tiber. The current beach is three kilometres away, in Lido di Ostia. Ostia is today still lying next to the Tiber, but the river runs along part of Ostia only. It is a meandering river, and in 1557 a branch was cut off by a major inundation of the river. This branch gradually filled in, and is now called Dead River (Fiume Morto). This old meander can still be seen as a wide dip in the terrain, to the right of the modern road that leads from the ticket office to the museum.

From Rome to Ostia and Portus.

In the lower left part are Ostia and Portus, separated by an artificial island, the Isola Sacra, created by a branch of the Tiber and a Roman canal.

The Via Ostiensis, followed by an aqueduct, connects Ostia and Rome. The modern railway more or less follows its course.

The Via Portuensis led from Portus to Rome. Between the two roads the meandering Tiber can be seen.

To the east and north of Ostia and Portus are salt-pans (salinae).

Near the modern town Acilia, further to the east, several archaeological discoveries have been made as well: villas and the ancient settlement Ficana.

On the coast to the south of Ostia was an endless series of villas, including one that was owned by Pliny the Younger.

Early Ostia

To the east of Ostia were salt-pans, where salt was probably already extracted in the Middle and Late Bronze Age (1400-1000 BC). There may have been a small village near the salt-pans in the Early Iron Age (1000-700 BC). Livius mentions Ostia twice in his accounts of the fifth century (and exceptional floods of the Tiber in 414 and 363 BC). However, according to ancient tradition (authors such as Ennius, Livius, Cicero and Dionysius of Halicarnassus) Ostia was founded as a colony of Rome earlier, by the fourth king of Rome, Ancus Marcius, who was thought to have ruled in the late seventh century BC. Even the year is mentioned: 620 BC. So far no remains of buildings have been found in or near Ostia dating from this period. If a settlement existed, then it must have been a small outpost, not even a village.

Fragments of an inscription from the Imperial period.

REG[i Rom(ano)]
[pri]MVM COLON[iam]
[c(ivium) rom(anorum)] DEDUX[it]

To Ancus
fourth king of Rome
from Romulus,
who after the founding of the City
first of all founded the colony
of the Roman citizens.

The Ostians, like many ancient authors, claimed that the city was founded as a colony by king Ancus Marcius.

The oldest settlement that has been found is the so-called Castrum. It was a rectangular military fortress (194 x 125.7 meters), with walls of very large tufa blocks. The current Forum is in the centre, and a few remains of the Castrum walls can still be seen around the Forum. The two main streets, leading to four gates, were called Cardo and Decumanus. These would create regularity in the street pattern of Ostia when the city grew. However, there is also a great irregularity in the lay-out of parts of Imperial Ostia. This must be the result of a very old road, perhaps from the sixth or fifth century BC, that started at the mouth of the Tiber and continued towards the south-east.

Remains of the Castrum wall. Photo: Daniel González Acuña.

From some historical events can be deduced that the Castrum was built in the fourth or early third century BC. Most modern historians have suggested that it was erected in either 349/8 or 338 BC, a period when Rome had to battle pirates and was at war with its neighbours. The oldest pottery found in the Castrum has been dated to the period 380-340 BC. More recently other proposals have been made: the late fifth century BC, in view of the origin of the tufa blocks (from Fidenae); the year 311 BC, because two duumviri navales, officials in charge of ships, were appointed (but they may also have been active in the harbour district in Rome itself); 300-275 BC, because pottery found next to the foundation of the walls belongs to that period (with the suggestion that the older pottery could be the remains of votive offerings from an older temple, curiously isolated however). According to the most convincing hypothesis the Castrum belongs to the period 292/1 BC (when the god Aesculapius was taken to Rome, but Ostia is not mentioned) to 278 BC (when a Carthaginian fleet is said to have reached Ostia).

The Republican period

In the third century BC Ostia was primarily a naval base. In 267 BC it became the seat of one of the quaestores classici (officials taking care of the fleet), the quaestor Ostiensis. The office was related to the Punic wars, with Carthago. Ostia now played an important role as military harbour, and for that reason the inhabitants were freed from military duties, so that they could remain at work in the harbour. In the second century BC Ostia gradually changed to a commercial harbour. The population of the city of Rome was growing after military successes. Grain was imported from Sicily and Sardinia, later also from Africa Proconsularis, modern Tunisia, that became a province in 146 BC. The quaestor's main duty was now the supervision of the import of grain.

In the second or early first century BC the north-east part of Ostia, along the Tiber, was marked as public ground (reserved for Rome) by Caius Caninius, praetor urbanus (from Rome). Little is known about the settlement in this period, because Ostia was almost entirely rebuilt in the second century AD. In the lower levels remains of domus, rich houses, were found, comparable to those in Pompeii and Herculaneum.

Mosaic from a domus, found in the older levels. First century AD. Photo: Wikimedia, Notafly.

In 87 BC, during the civil war between the supporters of Sulla and Marius, the city was occupied and plundered by Marius. In 69/8 BC the city was plundered again, this time by pirates, who also destroyed a fleet in the river harbour. Not long afterwards Pompeius dealt with these pirates. It is probably the latter invasion that led to the building of new town walls by Marcus Tullius Cicero, in 63 BC. The work was finished in 58 BC by Publius Clodius Pulcher, a political rival of Cicero. The new walls enclosed an area that extended far beyond the walls of the Castrum. Until the first century BC Ostia was governed from Rome, but from now on, possibly from the time of the building of the new walls, Ostia had its own government. The oldest fragment of the town records (fasti) is dated to 49 BC, but it is clear that this is not the start of the list.

Important monuments from the first century BC are the Four Small Temples and the Temple of Hercules. These were built by members of the local aristocracy: Publius Lucilius Gamala, four times duovir ("mayor"), and Caius Cartilius Poplicola, eight times duovir. Gamala seems to have sided with Cicero. His career has to be dated to the years 90-60 BC, or 70-35 BC. Poplicola was a supporter of Octavianus, and together with Agrippa he ensured the loyalty of the harbour to the later Augustus. Gamala and Poplicola were honoured by the Ostians for military deeds, including the repelling of an attack by Sextus Pompeius (son of the Pompeius who had fought the pirates), during the civil war in the years 40-36 BC. The ties of these men with Rome were not an exception: in this period the leading families of Ostia were also influential in Rome.

The early Imperial period

Marcus Agrippa, right-hand man of Octavianus-Augustus, built a theatre in Ostia for approximately 3000 spectators, in the period 18-12 BC. The growing importance of Ostia is here reflected by the use of marble, still exceptional in this period. Marble was also used for the decoration of the monumental tomb of Agrippa's collaborator Poplicola. It is not clear when the Forum, the central square, was laid out, but during the reign of Augustus, at the end of the first century BC, two temples were built at its north side, possibly a Capitolium and a Temple of Jupiter. In the early first century AD a Temple of Roma and Augustus was added at the south side of the Forum by Tiberius (14-37 AD). Claudius (41-54 AD) sent urban cohorts to Ostia to fight fires. An aqueduct was built, and during the reign of Vespasian (69-79 AD) the city wall was converted to an aqueduct, taking water to the southern part of the city. Under Domitian (81-96 AD) the level of Ostia was raised approximately one meter whenever new buildings were erected, probably to protect them from Tiber flooding. During his reign or a little later the present meeting hall of the town council and the main basilica were built to the west of the Forum. The Jewish community in Ostia built a synagogue near the beach in the middle of the first century.

The ruins of the synagogue. Photo: Parco Archeologico di Ostia Antica.

In this period Ostia was ruled by a small number of "aristocratic" merchant families of free descent. They lived in atrium-houses near the centre of town. Officials from Rome ensured the food supply of the Urbs. In 23 BC Tiberius was quaestor Ostiensis, the first step in his career. In 44 AD Claudius withdrew the quaestor from Ostia and created a new office, that of procurator annonae Ostiensis ("procurator of the food supply"), who worked for the praefectus annonae ("prefect of the grain-supply") in Rome, who had been introduced by Augustus in the period 8-14 AD. These procurators were not senators, but belonged to the equestrian order. They were supported by clerks called for example tabularii, "keepers of archives", and dispensatores, "treasurers". Many officials, such as the governors of provinces, now departed from and arrived in Ostia. In 2 AD Lucius Caesar, grandson of Augustus, died in Massilia (Marseille). His corpse was taken to Rome, and the local calendar says that "his body was carried through Ostia by magistrates clothed in black, followed by a crowd carrying burning tallow-candles, while the buildings were decorated fittingly".

Ostia was essential for the supplying of Rome, and therefore for the Emperor. Imperial slaves and freedmen worked in the harbour. Eventually Ostia would became the main harbour of Rome, taking the place of Puteoli in the Bay of Naples, but this took some time. The reason for this was that the shoreline near Ostia did not offer natural protection to ships. Small boats could sail up the Tiber to Rome. Large ships unloaded at the Tiber quays of Ostia, very large ships out at sea. For these large ships Ostia was a dangerous place.

In 42 AD Claudius - a frequent visitor of Ostia - started the construction of an artificial harbour, a few kilometres to the north of Ostia. A huge basin was dug out, protected by two curved moles and with a very tall lighthouse, a copy and improvement of the famous Pharos of Alexandria. Channels connected the basin with the Tiber and created an artificial island between Ostia and Portus, called Isola Sacra ("Sacred Island"). The completion of the work was celebrated in 64 AD, during the reign of Nero. But already in 62 AD the harbour was in use: in that year 200 ships in the basin perished during a storm, perhaps a tsunami (in the same year Pompeii was struck by an earthquake). From now on Ostia was the main harbour of Rome for goods from the western half of the Empire. Puteoli remained important, perhaps as Rome's harbour for the eastern, Greek-speaking half of the Empire.

Trajan's hexagonal harbour basin. Photo: G. Verhoeven - Portus Project.

Trajan built a second, hexagonal basin behind the basin of Claudius. The work was carried out in the years 106-113 AD and included improvements of the Claudian harbour. In the course of the second century the grain fleet from Alexandria in Egypt sailed to Ostia instead of Puteoli. The harbour district was controlled by an Imperial official, the procurator Portus Ostiensis, called procurator Portus Utriusque ("of both harbours") after the construction of the second harbour basin. The buildings surrounding the harbour basins still lie largely unexcavated next to and below the airport. The area is very promising and exceptional discoveries have been made. It was and partly still is private property of the Torlonia family.

Ostia's golden years: the second and early third century

During its hey-day Ostia was a densely populated city, with a large variety of buildings, and a mixed and "international" population. But first and foremost it was a harbour city, serving the needs of Rome, characterized by warehouses and the seats of guilds. Ostia was much smaller than harbour cities such as Alexandria and Carthage. Not only was Ostia smaller, it was also more functional. Porticos flanking the streets are found throughout the city, but identical porticos facing each other are exceptional. There were only a few squares. There was no amphitheatre, no circus (Puteoli, formerly the main harbour of Rome, had a theatre, two amphitheatres and a circus). The sudden commercial opportunities that arose after the construction of Trajan's harbour were seized by entrepreneurs, who were interested in profit, not in developing Ostia's non-functional infrastructure.

The Emperors and Ostia

The addition of the harbour district was followed by a building boom and great prosperity in Ostia. The overwhelming majority of the buildings that have been excavated was built in the first three quarters of the second century, especially during the reigns of Hadrian and Antoninus Pius. The prosperity lasted until the Severan period, that is the early third century.

When the work on Trajan's harbour was finished, the builders turned their attention to Ostia and started rebuilding the city, supervised by Hadrian (how they were able to take over the properties of the local aristocracy remains a mystery). Hadrian was twice duovir of Ostia, and in an inscription he was honoured because he had "preserved and enlarged the colony with all his indulgence and liberality" (colonia conservata et aucta omni indulgentia et liberalitate eius). It was not self-evident that Ostia would flourish: it was the Emperor who ensured that it would be the organisational and financial centre. During the reign of Hadrian the north-east part of the city (including the area that had been reserved by Caius Caninius) was rebuilt with a rectangular plan. Fire-fighters (vigiles) from Rome were stationed in new barracks in this area. A huge Capitolium was erected to the north of the Forum. Large baths were donated by Hadrian and his successor Antoninus Pius, and by Gavius Maximus, an official in Rome. Warships from Misenum, a military naval base, were stationed at Ostia. The sailors may have taken governors and Emperors to the provinces. They were also in charge of the awnings of the Colosseum in Rome.

Aerial view of Hadrianic buildings, including the Capitolium, in the centre of Ostia. Photo: Parco Archeologico di Ostia Antica.

Commodus enlarged the theatre and refounded the colony as Colonia Felix Commodiana ("Happy Colony of Commodus"), a name that would be forgotten however after he was killed in 192 AD. in the Severan period building activity was mostly restricted to repairs and modifications. Septimius Severus also improved a road along the beach, connecting the mouth of the Tiber and Terracina. Probably during the reign of Alexander Severus, the last Emperor of the Severan dynasty (222-235 AD), a large round temple was built to the west of the Forum. It resembles the Pantheon in Rome. Inscriptions testify to the existence of an Imperial palace in Ostia.

The local government

The most important magistrates were two duoviri. They were appointed for a period of one year and presided over the city council. They acted as judges, but could not pass sentence of death, which could only be done in Rome. Therefore the symbols of their power were not fasces, a bundle of rods and an axe, but bacilli, rods without an axe. The duoviri were supported by two aediles, who supervised the markets, the standard weights and measures, and public facilities. Finances were in the hands of two quaestores aerarii. The aerarium, the city treasury, was presumably stored in the basement of the Capitolium. A curator operum publicorum et aquarum oversaw public buildings and the water supply. From the period of Trajan the quaestor alimentorum took care of poor children.

Arches of the aqueduct.
Photo: Simon Bakker.

Portrait of Trajan found in Ostia.
Photo: Wikimedia, Sailko.

The city council had 100 (later 110) members called decuriones. In order to be admitted one had to be freeborn (which was also true for the sons of freed slaves), at least 25 years old, and wealthy enough to pay an entrance fee. The council itself chose new members. It was supported by secretaries (scribae), attendants (lictores), messengers (viatores), town criers (praecones), and public slaves and freedmen. The latter were organized in a guild. In the early Imperial period the people could elect the duoviri, but by the beginning of the second century AD this was no longer the case. Elections had ceased, and the city council appointed the duoviri.

Religious offices also formed part of a public career (cursus honorum). Vulcanus was the protective deity of Ostia, and his main priest, the pontifex Volcani, had general control over all temples in the city. He was assisted by praetores and aediles. He may be compared with the pontifex maximus in Rome, an office that was always held by the Emperor. In Ostia this office was the summit of a political career. It was held for life. Minor religious offices were the priesthood of Roma and Augustus, related to the temple to the south of the Forum, and the priesthood of a deified emperor.

Ostia also needed patrons, who could stand up for the interests of the city in Rome. Therefore patroni were elected who had been successful in Rome. If possible, men of Ostian descent were selected.

Trade and commerce

Skippers from many provinces transported goods to the harbours, for example wine from France, olive oil from southern Spain, grain from Tunisia and Egypt, marble from Tunisia, Greece and Turkey, and metal. Upon arrival the goods were stored in horrea (warehouses), and transported later to Rome along the Tiber in tow-boats pulled by men (codicarii), in late antiquity by oxen. The skippers (navicularii) and some local craftsmen and merchants were organized in guilds called collegia. The "control room" for this complex organization was the Square of the Corporations, behind the theatre. Here representatives of the guilds and of the administration had small offices, identified by mosaics with inscriptions and depictions of ships, the lighthouse of Portus, grain measures, and dolphins. It was the Roman alternative for email and the mobile phone.

The office of the "navicul(arii) et negotiantes Karalitani", the skippers and merchants from Cagliari (Sardinia) on the Square of the Corporations.
The cargo ship below the text is flanked by grain measures. Photo: Gerard Huissen.

Both free and freed people could join the guilds. The presidents of the guilds were called quinquennales. They held the office for a period of five years. The treasurers were called quaestores, the ordinary members formed the plebs. And, like the colony, the guilds could have patrons. The largest local guilds were those of the builders and ship carpenters (fabri tignuarii and fabri navales), with hundreds of members. The ship carpenters repaired ships, which was an ongoing activity, and most likely also built new ones. The guilds cannot be compared with mediaeval guilds, if only because membership was not obligatory. They were of social importance, remembering for example deceased members. If the economic role was crucial, the guild was given the status of "body" (corpus). The members then had to perform duties in the public interest, but in return received exemptions from public duties, comparable to our tax exemptions.

The people

Through immigration and the import of slaves the population rose to perhaps forty thousand, including many slaves. Most slaves were taken to Ostia from the Greek-speaking East. Many must have been foundlings, but the breeding of slaves must also have been a profitable trade. Most families had at least one slave, and there were many Imperial slaves, working in the harbour and warehouses. Many slaves were manual labourers, others were clerks and accountants. The most frequent slave-name is Felix: "Happy".

In this period we witness a rise in society of a middle class of traders and merchants, often not of Ostian origin. Some were free immigrants, others freedmen. If we believe the inscriptions, then the vast majority of the population of Ostia in the later second century was made up of freedmen and their children. It is possible however that freedmen felt the need to self-advertise their newly acquired status, and that, as a result, they are over-represented in the epigraphic record. Especially people from North Africa started to play a dominant role, but France, Spain, Greece, Turkey, Syria and Egypt are also documented. We encounter the new arrivals as procuratores annonae, in the city council, and involved in all phases of the grain-supply: as owners and skippers of ships transporting grain over the sea and the Tiber, as grain merchants (mercatores frumentarii), and as grain weighers (mensores frumentarii).

The grain measuring centre of Ostia. Photo: Jan Theo Bakker.

Freedmen were often active in the trade of their former master, now their patron. The guild of the Seviri Augustales, focusing on the cult of the Emperors, was entirely made up of freedmen. It resembled the trade guilds. And as magistri vici ("ward masters") freedmen were in charge of the cult of the Lares Compitales, deities worshipped at crossroads.

The vast majority of the population lived in rented apartments, some luxurious, others quite simple. Most of the apartments were on the upper floors of high-rising buildings made of thick concrete walls faced with bricks and sometimes small tufa stones. The expensive apartments were decorated with excellent paintings and mosaics, and had their own kitchen and latrine. Less fortunate people used communal latrines and public water basins. All inhabitants took good care of their bodies: the number of public baths in Ostia is astonishing.

The interior of an expensive rented apartment. Photo: Klaus Heese.

A large necropolis on the Isola Sacra, near Portus, shows that apartments must also have been built near the harbour basins. The famous physician Galenus worked in Ostia in the later third century. He wrote: "All the doctors in these places [Ostia and Portus] are my friends, and both are populous centres". Still, Portus does not seem to have had a very large residential area, and many people who worked in Portus must have lived in Ostia. They crossed the Tiber with ferries (there does not seem to have been a bridge) and could be taken all the way to Portus on a canal dug through the Isola Sacra.

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: Daniel González Acuña.

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.

From the eleventh century to the present day

From the eleventh to the fourteenth century Ostian marble was reused in the cathedrals of Pisa, Florence, Amalfi and Orvieto. A document from 1191 mentions a spot in Ostia called calcaria. This is a reference to a lime-kiln, in which marble (floors, statues, inscriptions) was burned to be used as mortar. Several lime-kilns have been excavated. The search for marble was easy, because Ostia was not entirely buried. In August 1190 Richard Coeur de Lion landed at the mouth of the Tiber. He saw "immense ruins of ancient walls", and a place called "Le Far de Rume" - the remains of the lighthouse (Pharos) of Portus. Vast amounts of bricks must also have been dug up, to be used in Rome.

In the fifteenth century the castle of Gregoriopolis was rebuilt by cardinal Giuliano della Rovere (this is the present castle). It had to protect Rome from incursions by raiders. In 1557 there was a major inundation. The meandering Tiber changed its course. The branch of the Tiber along the castle was cut off, so that the castle became useless. The old branch is now filled with earth and known as Fiume Morto ("Dead River"). The inundation of 1557 also destroyed a large stretch of the ancient Tiber quays.

The borgo of the modern village Ostia Antica. Photo: Parco Archeologico di Ostia Antica.

From the fifteenth to eighteenth century promising ruins were searched by foreign visitors for inscriptions and statues. These ended up in private collections in England, France, Portugal, Spain and Russia (now mostly in national museums). The random searching of the ruins was forbidden by Carlo Fea, director general of antiquities, in the early nineteenth century. The first excavations, initiated by pope Pius VII (Ostia belonged to the Vatican), were carried out by Giuseppe Petrini in the years 1801-1805. Between 1824 and 1834 there was a renewed hunt for treasure. More or less structural activities began once more in 1855, under the auspices of pope Pius IX. The excavators were uncle and nephew Pietro Ercole and Carlo Ludovico Visconti. They too focused on inscriptions, statues, mosaics, and paintings, that were taken to the Vatican museums. Sometimes marble and granite was taken to Rome as building material. From 1870 Ostia was no longer a papal domain, but owned by the new Italian state. The excavations were continued by Pietro Rosa and Rodolfo Lanciani. In 1887 Hermann Dessau published the Ostian inscriptions in the Corpus Inscriptionum Latinarum (CIL), volume XIV.

Wealthy foreigners started to visit Ostia as tourists in the 19th century. The site was reached with some difficulty with carriages. The railway between Rome and Ostia was opened in 1924. The present-day museum was built. Starting in the late nineteenth century the marshes were drained and restored to agriculture. This was the work of colonists from Ravenna. The malaria was completely eradicated after the Second World War by the Americans, who sprayed DDT.

A monument in the modern village for the colonists from Ravenna who drained the marshes of Ostia.
Photo: Wikimedia, Lalupa.

Truly scientific research started in 1907 by Dante Vaglieri. The north-east part of the city was now excavated systematically. Vaglieri died in 1913. The year before, the first monograph about Ostia had been published: "Ostia, Colonia Romana", by Ludovico Paschetto. Important work was also done by the French archaeologist Jérôme Carcopino.

Vaglieri was succeeded by Guido Calza, who was supported by architect Italo Gismondi and inspector Raffaele Finelli. Slowly more ruins were unearthed. In 1930 a supplement to the CIL appeared. In 1938 one-third of the city had been excavated. But then extensive, hurried excavations began, lasting until 1942. The initiator was Mussolini, who wanted to present Ostia during a world-fair, the "Esposizione Universale di Roma" (EUR). The excavated area was more than doubled. More than 600.000 cubic metres of earth were removed, that had reached a height of 4 to 12 metres above the ancient street level. Needless to say that much information was not recorded during these five years. The world-fair never took place. Calza died in 1946.

After the Second World War the series "Scavi di Ostia" was published. Excavations continued on a very small scale. In 1960 a monumental, historical study about Ostia was published: "Roman Ostia", by Russell Meiggs, working in Oxford (an updated edition appeared in 1973). A detailed archaeological guide, written by Carlo Pavolini, was published in 1983 (updated in 2006). Geophysical research by the German Archaeological Institute and the American Academy in Rome provided a wealth of information about the unexcavated area, and led to several important discoveries, such as that of a Christian basilica, and of a small harbour in the north-west part of the city. Similar geophysical research also took place in Portus and on the Isola Sacra by the University of Southampton. The University of London contributed to investigations of the area to the south of Ostia. The Ostia bibliography on this website contained over 3200 titles in 2022.

In Scavi di Ostia volume I the nomenclature of Ostian buildings was standardized. In antiquity Ostia was divided in five or more regions, but we do not know their borders. The excavators divided the city in five modern regions, and furthermore in blocks (insulae) and then individual buildings. An example of the numbering system is: Tempio d'Ercole (Temple of Hercules), I,XV,5 = building 5 in block 15 in region 1.