Why are Roman ruins always underground

by ThiccyBiccies

In Lisbon the excavated Roman amphitheater was several meters bellow street level. And I was wandering how it managed to sink so far bellow the modern day city of Lisbon and why do Roman ruins tend to be found underground? It’s called Teatro Romano btw

Zmyeevich

I started writing an answer for this, but then I noticed, it has been asked before and the answer giving was much better than what I could have given. Here is a link