...I have a collection of images of circular and concentric ringed structures, some with standing stones, some with mounds, some with central features, that number in the hundreds; throughout europe, the Sahara, Iran, and South America. I think I even have one from Tibet. I am inclined to believe it was not a defensive layout at all, but, because they are so wide-spread, they may be an imitation of something the people saw, perhaps a celestial phenomenon.
The design is also repeated in rock art, and Stone Henge also follows a similar lay-out.
It does raise the question of population however. How many people worked for how long to raise the structures?
[I am inclined to believe it was not a defensive layout at all, but, because they are so wide-spread, they may be an imitation of something the people saw, perhaps a celestial phenomenon.]
Could very well be. Fortifications that size presumes large numbers of people, many thousands, just to man the walls. Which implies being attacked by hordes of many thousands, on a rather regular basis. So maybe they were celestial/religious.