🇺🇸 United States · Earthwork
Anderson Mounds
Middle Woodland Hopewell–Adena 250 BCE–200 CE · Hopewell tradition (Adena antecedent)
Hopewell circular enclosure and Great Mound, 250 BCE–200 CE.
🇺🇸 United States · Earthwork
Great Serpent Mound
Disputed: either Adena 320 BCE–200 CE or Fort Ancient 1070–1200 CE (latest C14 favors Fort Ancient 1120 CE) · Adena culture or Fort Ancient culture
Quarter-mile (411 m) effigy mound in shape of serpent with oval head swallowing an egg, 3 ft high, coiled tail atop meteor-crater plateau above Ohio Brush Creek, largest surviving effigy mound in…