Some of these sites go back far more than people think. Excellent thread, btw!!

Just to add an opinion, I feel the people responsible for the base layer of construction (cyclopian and uniform the world over)left long before the event that wiped their culture and history from Earth. What we find is the ruins of their cattle, built in remembrance of The true builders... Kinda like how tribes in remote areas develop cargo cults after meeting modern man and his gifts.

There are sites in Petra and in India that defy all logic. I'm talking about entire "temples" carved from bedrock outcroppings. Some are in the hardest stone on the planet.

The world we live in is nothing but a stage upon the Earth. This world too shall pass and become a mystery to those we create or leave behind. :)