Stonehenge.
Roger Ressmeyer / Corbis
For a set of craggy rocks in an English field, Stonehenge’s ability to capture the imagination is impressive. The ancient monument — composed of massive stones arranged into concentric circles by unknown builders — is referenced almost as far back the Norman Conquest, when an English historian remarked in 1130 A.D. that “no one can conceive how such great stones have been so raised aloft, or why they were built here.” That certainly hasn’t kept many from trying. It seems like everyone has a theory for why the ruins were constructed. Some are more plausible than others.
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