On the ridge above this road and the Fox River lies a series of prehistoric earthworks, visible remnants of both social and ritual behavior of one of Wisconsin’s unique prehistoric cultures, the Effigy Mound Indians. The conical mounds are from the Middle Woodlands time, circa 200 BC-700 AD. The effigy and linear mounds are representative of Late Woodlands time, circa 7900 AD–1400 AD. Archaeological excavations reveal the use of some as burial and religious sites, while others have yielded no artifacts, leaving their purpose uncertain and raising questions about whether they served as clan symbols or astronomical devices.