Serpent Mound
300 BCE – 1070 CE
The largest serpent-effigy earthwork on Earth — a sinuous, 411-metre-long mound shaped like an uncoiling snake, built atop a ridge overlooking a Ohio Brush Creek in southern Ohio. Who built it and when remains one of North American archaeology's more contested questions: early 20th-century excavation attributed it to the Adena culture around 300 BCE, while 1990s radiocarbon dating pointed instead to the later Fort Ancient culture around 1070 CE — a debate that has never been fully resolved.
HellenisticMedievalHigh Medieval
69
