Ostia was a Roman port city, perhaps the first colony (colonia) of Rome, located at the mouth of the Tiber River into the Tyrrhenian Sea, about 30 km west of Rome– the ruins preserved to this day are one of the largest in terms of area and the best-preserved (especially frescoes and mosaics) in Italy. Since the coastline has followed the sea since ancient times, today the port is still on the Tiber, but about 3 km from the beach. The name of the city comes from the word ostium, meaning “estuary”.
According to the writings of authors such as Ennius, Livius, Cicero and Dionysius of Halicarnassus, Ostia was founded by the fourth king of Rome, Ancus Martius, in 620 BCE. So far, no archaeological remains that could be dated to this period have been found – the oldest are dated to the 4th century BCE.
The oldest structures visible today are: Castrum (military camp) from the 3rd century BCE and Capitolium (temple of Jupiter, Juno and Minerva) – not much younger. castrum walls are a great example of the opus quadratum technique, involving the use of stone blocks of the same size in parallel alignment, often without the use of mortar. This technique was very popular in the times of the middle republic.
In 68 BCE Ostia has been invaded by pirates. During the attack, the port was engulfed in fire, the consular fleet was defeated and two prominent senators were kidnapped. The pirate attack caused great panic in Rome. Following the initiative of Pompey the Great, people’s tribune Aulus Gabinius introduced a new law at the Forum Romanum – Lex Gabinia – enabling Pompey to gather an army and defeat the pirates. Within a year, Pompey managed to defeat the pirates and significantly curtail the range of attacks in the Mediterranean Sea. Over time, the city was rebuilt and received defensive walls on the initiative of Cicero.
For the republics, the natural landscape at the mouth of the Tiber was used as a port. The city was at its best during the imperial era. During the reign of Emperor Tiberius, the first Forum was established. The city was also enlarged by a port that was built at the northern mouth of the Tiber – Fiumara Grande. The new port is named Portus which is “port”. It was only Emperor Claudius who built an artificial harbour. As the port was often silted up, it was decided to build a replacement port for Emperor Trajan, the construction of which was completed in 113 CE. It was hexagonal in shape to reduce erosion from sea waves. This move resulted in an outflow of “maritime business” and the gradual financial collapse of the port.
The city was full of all possible services an ancient city could experience at that time. The port was naturally equipped with a lighthouse. In addition, there was a Synagogue in the city (the oldest one so far located in Europe). Also discovered was Mithraeum, a temple dedicated to the god Mithra. This deity had a huge crowd of followers in the city, especially the workers who made up the majority of the city’s population. Over time, Trajan decided to further extend the city limits by the sea to the north. It was another port at Centum Cellae (present-day city of Civitavecchia).
Emperor Hadrian ordered a channel connecting the port with the Tiber to be made. Then Ostia flourished as a city, additionally enriched with buildings by Marcus Aurelius and connected with the “Eternal City” by a new road – Via Portuensis – going along the right bank of the Tiber.
The main street of Ostia was Decumanus Maximus – the original, ancient road leading past the ancient necropolis through the site of the former main gate – Porta Romana. In the city, you can come across the ruins of the imperial baths complex, former port warehouses and the thermal baths of Neptune. In the centre of the former town, at the main square, there was an antique theatre from the 2nd century CE, which could seat about 4,000 spectators.
Near the main square, the Capitol building was reconstructed, surrounded by the forum (with the temple of Augustus) and thermal baths. The best-preserved house in Ostia is Casa di Diana with a courtyard and a complex of numerous halls. Equally interesting is Thermopylae – an ancient cafe with preserved murals that function as a menu.
The final section of Decumano Massimo leads eastwards – where in antiquity there was a marina – passing the remains of the houses of old craftsmen, merchants and sellers (including butchers, blacksmiths) through the remains of the gate Porta Marina (the other main gate was Porta Laurentina, on the south side of the city walls). Near the ancient coastline are the ruins of the Porta Marina thermal baths.
In the lower-left corner are Ostia and Portus, separated by an artificial island (Isola Sacra). The road via Ostiensis – with the accompanying waterworks – connected Ostia with Rome. The road via Portuensis led from Portus to Rome. You could see the meandering Tiber from both roads.
To the east and north of Ostia and Portus there were salt-rich lands (salinae).
In the 2nd century CE, the city had a population of 50,000 so at the turn of the 2nd and 3rd centuries CE reach 75,000 people.
The slow decline of the city began in the late imperial period, during the reign of Constantine the Great in the 4th century CE. Then the port, instead of being an active place of trade, became an evacuation point from Rome for wealthy aristocrats. With the political and military collapse of the city of Rome, Ostia lost its importance, and the port turned into a swamp over the centuries.