Some 2,000 years ago, ancient Rome’s lively international port city was right on the beach and at the mouth of the Tiber (ostium means “river mouth”). In the ensuing millennia the sea has retreated several kilometres and the river has changed course dramatically. Ostia was founded in the 4th century BC, first as a simple fort, but as Rome grew, the town became ever more important, as the distribution point for imports from around the Mediterranean. Grain was the most vital commodity, to feed Rome’s one million inhabitants, and so huge storage bins (horrea) were built here. Goods were sent up to Rome on river barges. Ostia’s heyday ended in the 4th century AD, and it died completely as an inhabited area about 1,000 years ago.