English: Effigy Mounds National Monument preserves more than 200 prehistoric mounds built by Native Americans. Numerous effigy mounds are shaped like animals, including bears and birds. These were built mostly in the first millennium, by peoples of the Woodland Culture. In 2017, they were featured in the America the Beautiful Quarters Program.

The monument is located primarily in Allamakee County, Iowa, with a small part in Clayton County, Iowa, in the midwestern United States. The park's visitor center is located in Harpers Ferry, Iowa, just north of Marquette.

Lidar-derived image of Marching Bears Mound Group, Effigy Mounds National Monument. Prehistoric earthworks by mound builder cultures are common in the Midwest. However, mounds in the shape of mammals, birds, or reptiles, known as effigies, apparently were constructed primarily by peoples in what is now known as southern Wisconsin, northeast Iowa, and small parts of Minnesota and Illinois. Exceptions are the Great Serpent Mound in south-eastern Ohio, and Mound A at Poverty Point, Louisiana, built in the shape of a large soaring bird.

Effigy Mounds National Monument takes in the western edge of the effigy region. The North Unit (67 mounds) and South Unit (29 mounds) are located where the counties meet along the Mississippi River. They are contiguous and easily accessible. The Sny Magill Unit (112 mounds) is approximately 11 miles (18 km) south of the other units, and offers no visitor facilities. Other mounds are located on remote parts of the Monument property. The monument contains 2,526 acres (10.22 km2) with 206 mounds, of which 31 are effigies. The largest, Great Bear Mound, measures 42 meters from head to tail and rises over a meter above the original ground level.

Source: Wikipedia

en.wikipedia.org/wiki/Effigy_Mounds_National_Monument