How big was the territory on the ancient city of rome that was able to keep 1 million people? | AskHistorians Archive Observer

How big was the territory on the ancient city of rome that was able to keep 1 million people?

by MAQS357

I doubt the Aurelian walls were able to keep all those people inside, I mean the Romans did not had 10 story building for housing did they?

kid_elagabalus

Well actually they did, tertullian actually mentions an insula (a sort of condominium) taller than the houses of the gods, and regular insulae could reach even nine stories