I found myself the guest of the Saudi Kings Khalid and Fahd back in '82. I got to see what the Before People were able to create (at their expense) in Egypt. Later, I got myself a job that came with paid vacations to anywhere and traveled extensively in Central and South America for as much as a month at a time. I maybe regret not being formally trained in Archeology, but if I had, maybe my mind wouldn't have been so open to the things I was seeing with my own eyes.
I'd tell you the Pyramids are just shocking to see the first time. When you look at the Sphinx, there's no doubt some bastard ruined what it had been to have his tiny little head carved onto it. But, it's the other 'attractions' there that are the most fascinating. There's so much more going on there.
If someone asks, "Who do you think built that?" My answer most always comes back, "People who could."
We want to believe people could do it again, but we can't. I don't think we've achieved as much during this cycle of civilization as the last one (or the ones before) were able to come up with.
I remember reading once that if almost every human on the planet died tonight ... in about a thousand years ... if another group of humans came together and organized, they wouldn't be able to see what we've managed to do in 'our time'. That the erosion would leave behind so little, the only things that would indicate an advanced society had existed before them would be radioactive piles that don't naturally occur.
So what if ... the demises of mankind are not strictly based on climatological change (ice ages or meteor strikes or solar phenomena)? What if we share this planet with a more advanced intelligent life? And, what if that intelligence periodically wipes us out, as we become a threat to it?