"From a small village on the Palatine, Rome became the largest metropolis of antiquity. Its first inhabitants came down to graze their herds and bury their dead in the damp and narrow valley, where the Forum later arose; after ten centuries, when Constantine moved the capital of the Empire to Byzantium, the built-up area of ​​Rome had a perimeter of almost twenty kilometers and a very numerous and dense population. The banks of the Tiber from Porta Trigemina to beyond the slopes of the Aventine towards the south were arranged through port works, in order to ensure the necessary supplies in abundance and regularly. Eleven aqueducts supplied such a quantity of water every day that it is estimated at one and a half billion litres. (Ugo Enrico Paoli)"