Rome

city · earth

A settlement on the lower Tiber that grew from a central-Italian city-state into the administrative and symbolic centre of a Mediterranean empire. Its position matters twice over: far enough upriver to be defensible, close enough to the sea (via Ostia and later Portus) to be fed by grain fleets from Africa and Egypt. Rome's own population at its imperial peak is itself an estimate, commonly placed near one million but argued down to c. 500,000 by some demographers; no ancient census of the city survives in usable form.