How many people lived in ancient Rome?

The men on the grain list

Rome never counted everyone inside its walls, but it counted the men it fed. Augustus lists his handouts in the record of his reign he left at his death. In 5 BC a cash gift reached 320,000 men of the city’s common people. In 2 BC he gave money to everyone then on the free grain list, just over 200,000 men (Res Gestae 15). Before him, Julius Caesar had cut that list from 320,000 names to 150,000, Suetonius says (Julius 41).

Those were adult male citizens. Add their wives and children, the slaves who did much of the city’s work, foreigners from every province, and the soldiers of the guard, and the total lands somewhere around a million. The weakest link is the number of slaves, which no source gives.

Where a million people slept

Rome had no sprawl of suburbs. When Aurelian walled the city in 271–275, his walls ran 19 kilometers (12 miles) and enclosed about 13.7 square kilometers (5.3 sq mi), under a quarter of the land area of Manhattan. Most Romans lived in insulae, apartment blocks of brick, concrete and timber, with shops opening onto the street and cheaper, smaller rooms the higher you climbed. Strabo says Augustus capped new buildings on public streets at 70 feet, about 21 meters (Geography 5.3.7). Two fourth-century guides to the city’s fourteen districts count 46,602 insulae and only 1,790 private houses, domus.

The poet Juvenal grumbles about it all: buildings that collapse, fires at night, carts that make sleep impossible. Augustus gave the city its first firefighters, seven cohorts of watchmen called the vigiles, in AD 6. One apartment block still stands at the foot of the Capitoline Hill, the Insula dell’Ara Coeli, its upper floors visible from the street.

Feeding the city

A city that size ate far more than Italy could grow. Josephus has a king remind the Jews that Africa fed Rome for eight months of the year and Egypt for four (Jewish War 2.383–386). Grain ships unloaded at Ostia and at Portus, the new harbors Claudius and Trajan dug beside it, and barges hauled the cargo up the Tiber.

Olive oil came in clay jars, mostly from southern Spain. Emptied and smashed, they were stacked near the river docks into Monte Testaccio, a hill of broken pottery 35 meters (115 feet) high, made of an estimated 53 million amphorae. It still rises in Rome today, a monument to the city’s appetite.

How sure can we be?

The million is a convention, a reasoned estimate rather than a count, and many historians think the real figure was at least that high. A minority, working from how densely people could live in the space, argue for half a million or fewer. No new source is likely to settle it.

What is certain is what came after. War, plague and the loss of Africa’s grain emptied the city. In 537 the Goths besieging Rome cut its aqueducts (Procopius, Gothic War 5.19). Rome would not hold a million people again until the twentieth century. For the whole empire, see how many people lived in the Roman Empire.