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. As of 2017, they have been featured on the US quarter.
The monument is located primarily in Allamakee County, 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.