America Unearthed: Season 1, Episode 8

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There are 800 very old, very mysterious, man-made stone sites in the Northeastern part of the United States. Forensic geologist Scott Wolter heads to rural Pennsylvania to investigate one of them--a meticulously crafted stone chamber buried underground in the woods. When he realizes it may have been a ritual bath chamber for a secret society, he embarks on a quest for answers as to who built, when and why.