4. Serpent Mound (Ohio)
Winding gracefully across an Ohio ridge, Serpent Mound captivates with its sheer size and mystery. This prehistoric effigy mound, over 1,300 feet long, was constructed by indigenous peoples more than a millennium ago. Its precise purpose is still debated—some believe it served as an astronomical observatory, others as a sacred site. Serpent Mound continues to intrigue researchers and visitors alike. Learn more at Ohio History Connection.
