The Italian and British archaeologists discovered “towers, shops, boundary walls and road layouts” beneath the earth of two public parks at Italy's lesser-known site, La Repubblica reported, “revealing all the grandeur of a real city that nobody could have imagined existed until today.”
They said the discovery, which spreads across 70,000 square metres, indicates that Rome was "split in two by the Tiber River in the First Century BC.”
The findings, described as “exceptional”, also reveal how important Ostia was as a trading port, which was abandoned with the fall of Rome, in the first 200 years of the millennium.
An ancient ship was also found there in 2011, while a Roman mausoleum and domus (house) were discovered in July last year.
"The presence of large storage areas in the part of Ostia north of the Tiber reopens the issue of the size of the trade that took place on the banks of the river," where the Tiber flows into the sea, Mariarosaria Barbera, superintendent of Rome's archaeological heritage, was quoted by news agency Ansa as saying.
Other remains at the site, located less than 30km from Rome, include a theatre, docks, mansions and baths as well as mosaics and frescoes.