Serpent Mound is a gigantic earthen sculpture in the form of a snake and one of North America’s most spectacular effigy mounds. Built on a spur of rock overlooking Ohio Brush Creek around 1000 A.D. by the Fort Ancient culture, it was likely a place of ceremonies dedicated to a powerful serpent spirit. The site stands on the edge of a massive crater, possibly formed by the impact of a small asteroid around 300 million years ago. Frederic Ward Putman studied Serpent Mound between 1886 and 1889, and largely through his efforts it became the first privately funded archaeological preserve in the United States.