Things are build on top of each other. In my city, there are leftovers of the old castle walls from the middle ages, which in the core are build on top of the

Things are build on top of each other. In my city, there are leftovers of the old castle walls from the middle ages, which in the core are build on top of the walls from the early medieval age and those in turn are built on top of roman walls. Or the social housing built after WW2 build on top of housing build in 1600s which in turn was build on top of social housing from 1516. Rubble over rubble over rubble for ages and ages. If you go into the nearby forests and dig, you'll find in order WW2, WW1, medieval, post roman and roman layered on top of each other. There is no tombs, mostly either a battlefield or simply a city being build on top of itself. A lot of European Cities tend to be like that and lots of places are like that. American cities by comparison are very very young (San Juan manages 400 years and some change, San Augustine comes second), our cities have grown organically over 3000 to 2000 years and through countless wars and catastrophes.