There are 210 known prehistoric American Indian mounds within the boundaries of the park, 31 of which are shaped in the similarity of bears or birds. From the overlooks at Fire Point, Twin Views, and Hanging Rock visitors are grovelling by the grand expanse of the Upper Mississippi River Refuge. Hiking to these quiet and picturesque points it is easy to understand why the people of the Woodland culture believed the ridgelines of these bluffs to be the ideal place for special cultural monuments. Effigy Mounds National Monument protects 206 prehistoric hillocks, 31 of which are in the shape of animal effigies. Between 600 AD and 1300 AD American Indians built these earthen mounds. Archaeologists believe they may have served important ceremonial purpose. Some mounds were used as burial sites and others, like multifaceted mounds, may have signified members of a family group.