Cataclysm overtook the Roman city of Pompeii with the eruption of Mt Vesuvius in AD 79. This was the period of the Pax Romana when the Roman Empire was at its height, and the empire and Italian peninsula were largely secure.

During this time, the city of Rome barely had any defensive walls (the impressive Aurelian walls were yet to be built). It was a source of pride to the Romans that their Eternal City didn't need defensive walls.