Effigy Mounds is a site of earthen mounds in animal forms (mostly in the shapes of bears and birds) made by Native Americans that lived around the Mississippi River in what is now northern Iowa. The monument preserves the mounds and has hiking trails that take you around the mounds and to views overlooking the Mississippi. There is a small museum at the entrance that tells about the mound builders and how they lived.
We got to go on Cory's birthday with his mom and our niece, making it an extra special day. It did storm while we were up there, but that really just made it all the more memorable. I definitely plan to go back the next time we are in the area!