I'm actually not sure that is the case. What we are seeing in these ancient civilizations is only the portion that has survived. A great deal, most of it, has n

I'm actually not sure that is the case. What we are seeing in these ancient civilizations is only the portion that has survived. A great deal, most of it, has not survived at all. When you look at places like Macchi Picchu, it wasn't a city that regular people lived in. It was built as more of a palace or estate for the king. If our civilization mostly disappeared, then things like large stone buildings, metal and stone statues would survive just the same and all of our disposable junk will have mostly disappeared leaving that skeleton of steel and stone. I suspect we would even leave quite a bit more than civilizations past considering all of our roads, bridges, dams, and other enormous concrete and steel structures that we have created.