We don't see it because our built environment tends to hide it and we're not usually looking closely, but it's there.
I can assure you that you can find plenty archeology within cities as well. Probably even more than on the countryside. It's just that it's all covered by several layers of development.
In the US the layer of soil where Clovis man was found has been used to determine a lower limit of where we can expect to find artifacts. But in many construction discussion groups you can find plenty of talk about stuff that has been found far deeper than the Clovis layers. Human civilization is far far older than we are led to believe.
it seems so!
But the pixies remember. That’s why they sometimes lead unwary travelers astray. The humans who live there now, some of them anyway, are aware of the pixies’ presence if not the full history, and try to keep relations friendly by offering gifts. An uneasy truce has been maintained this way for millennia.
Personally, I think they’re biding their time until the humans go virtual, uploading our minds into our own rune-carved megaliths; running on silicon and freeing up space. At that point the situation will be poetically reversed: the pixies will re-inhabit their ancient lands, this time without any bloodshed or battles. We will retreat of our own free will. There are, however, whispers of rumors that the clever, headlong rush towards the singularity is not driven by human minds alone…
Add to that some forgotten "landfills" of the 70s and you got a interesting underground plowing experience.