History of Ostia and Portus

'Ostia' comes from the word 'ostium' meaning 'mouth', because it was on the mouth of the River Tiber. It was Rome's principal port, and a large trading centre with international merchants and imperial officials living there.

By 267 BC, a prefect of the fleet was stationed there, which shows Ostia's importance. In 217 BC supplies were shipped from Ostia to forces fighting Hannibal in Spain in the Second Punic Wars.

In 204 BC a stone representing Cybele was brought to Ostia from Phrygia to fulfil a prophecy that Rome would avert catastrophe with her help. In 87 BC, Marius sacked Ostia during a civil war, and Ostia was then refortified. 

Ostia grew as the demand from Rome grew. However, the Tiber was too narrow at Ostia and the riverbed was silting up, so by the mid 1st century BC small and medium ships were alright, but larger ships had to wait at sea and be unloaded by smaller ships, which took longer and was dangerous in bad weather. 

Ostia's position meant that it was vulnerable to piracy, and the town was sacked by pirates in 68 BC.

Plutarch said that Caesar planned to build another port, but this never happened. Augustus also never did this, but Claudius, in an attempt to strengthen his power, did two things ~ invaded Britain, and tried to sort out the grain problem.

Tensions about grain were high, and Claudius would have remembered that Octavian had nearly been stoned over bread shortages by starving, angry Romans.

Claudius promised corn suppliers that he would underwrite any losses to their cargo if they continued to ship in winter, so they were happy to risk the bad weather. This was a short-term solution while he built proper port facilities to the north of Ostia.

Breakwaters were built on either side of a mole. A lighthouse (pharos) was built on top of the mole to guide ships in. The work took until 64 AD to complete and was celebrated by Nero on coins.

In 47 AD, Claudius had started drainage in Ostia to prevent seawater flooding into the city and spreading to Rome. He also stationed a fire service there to protect the grain warehouses.

Within 50 years, Trajan (98-117) had to improve the harbour and created a hexagonal port.

A storm in 62 AD wrecked 200 ships because the Claudian harbour was too large, so Trajan made it more secure. 

A new canal, Fossa Traiana, connected the Tiber to the port. This led to Ostia becoming the commercial HQ for administering Rome's food supply, and huge warehouses were built.

By the mid 2nd century, Ostia was reaching its peak with intense building. The new facilities such as the Forum Baths and temples to Mithras attracted settlement, and the Portus lost importance as it evolved into a town. 

In the 4th century, power and influence passed to Portus when Constantine transferred Ostia's civil rights there. 

By the 5th century Rome was in decline and by the mid 6th century it was in terminal decline. The shift of the Tiber and its silting made the port more swampy, so the population moved to villages away from the coast.