>But imagine that landscape thousands of years later (let's say shortly after the extinction of our species): the trees are gone; the earth has been levelled; structures of metal and stone stand in dissarray. What you are imagining are formal structures imposed upon the earth by man. The fact that the structures are utilitarian does not mean that they teach you nothing about man. Interpretation of those relics would reveal facts about the way we lived, the technology we had at our disposal, and what we conceived as our goals in life.,

I hear what you're saying Nick, and I don't disagree with it, but how accurate is the 'interpretation of those relics' going to be? If people today build wonderful astronomical, sacred theories around stone circles (when in fact some of those circles may have actually just been corrals) then something has gone seriously wrong with the interpretation. We can marvel at the effort and ingenuity of the people who built ancient structures but if we then label the reasons for their efforts with the wrong interpretation we are doing them (and ourselves) a great disservice.