43.0888°N, 91.1856°W.
Concentration of pre-contact earthworks along the Mississippi River bluffs in northeastern Iowa, formally preserved as Effigy Mounds National Monument since presidential proclamation in 1949. The Effigy Mounds complex contains 206 known mounds within the current monument boundary, including 31 in the recognisable shapes of bears and birds; the most famous group, the Marching Bear Group, consists of ten linked bear effigies arranged in a single procession across the bluff top. The mounds were built between roughly 750 and 1400 CE by Indigenous communities of the Late Woodland tradition known archaeologically as the Effigy Mound culture. The bear effigies average 24 to 30 metres in length and roughly 1 metre in height, constructed by careful basket-loading of soil onto prepared ground surfaces. Descendant communities include the Ho-Chunk, Iowa, Sac and Fox, and several other Upper Mississippi nations who continue to hold the site as ancestral ground.
A bear-shaped earthen monument the size of a basketball court was built one woven basket of soil at a time.