I found an interesting video by way of Physics Buzz, and thought I should pass it along (it’s about 6 minutes in length, but well worth your time). Wally Wallington, a retired construction worker, may well have figured out how a handful of people could have constructed Stonehenge — with just some rocks and a bit of timber to use as moving “equipment.”
The “trick” involves the use of just a few basic principles of physics, and some non-intuitive motions of the blocks. But don’t take my word for it, watch the video and see for yourself. The Physics Buzz post has a bit more explanation of the physics involved. And if you’d like to see more, Wally has his own website here.