Rome was quite large even during the time of the Roman Empire- population around 700,000 in 3rd century with about 40,000 of these apartments (Insulae). They were mixed in with the large homes of wealthy people and opposite of today the shops were on the ground floor, wealthier people above the shops, and poorest on the top floor. Fire was a big problem and there were no “elevators” . You had a better chance of escaping a fire if you lived on the first floor than the fifth. This photo also shows the remnants of an aqueduct. There are no intact aqueducts (used for bringing water) because if you were trying to conquer Rome the first thing you’d do is cut off the water supply.