Why archaeologists keep finding ancient cities beneath modern ones

Walk through the streets of Rome, London, Jerusalem or Delhi and you may be standing above a city that is hundreds or even thousands of years older. In Rome, archaeological deposits beneath the modern city can reach several metres in thickness. In London, Roman remains have been found beneath modern streets and buildings. In Jerusalem, archaeologists have documented multiple layers of occupation, with some areas containing many metres of accumulated earth and building debris.This is not a coincidence. Ancient cities were usually built in places that offered advantages like access to water, trade routes, defensible ground, fertile land or political importance. Those advantages did not disappear simply because one civilization declined. So, in many cases, the next population returned to the same location, repaired what remained, demolished older structures or built directly over them.