10 U.S. Landmarks That Have Left Experts Stumped – And 10 Whose Mysteries Have Now Been Unraveled


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The United States has many stunning historic sites – no small number of which date from millennia before European settlement of the land. And while careful study of some of these archeological gems has revealed their secrets, other sites have baffled researchers with enduring and intriguing mysteries. For instance, how was the extraordinary Spider Rock in Arizona created? Here, we reveal the answers to this and many other enigmatic questions about stunning U.S. landmarks.