Effigy Mounds National Monument; Iowa. Photo by JeromeG111/Flickr (Noncommercial Use Permitted with Attribution/No Derivative Works).
Effigy Mounds National Monument
The National Park Service preserves over 200 American Indian mounds in the picturesque upper Mississippi River Valley in Iowa. These mounds are considered sacred by many Americans, particularly the 18 Native American tribes that are culturally associated with the monument.