Effigy Mound National Park Quarter, Iowa. "The park is home to more than 200 mounds in a wide variety of forms, including more than 30 animal or bird-shaped “effigy” mounds for which the park is named. Often more than 100 feet long individually, many of these animal and bird shaped mounds are perched high atop rugged bluffs overlooking the adjacent Mississippi River." 24mm, Ag. ref. https://www.usmint.gov/coins/coin-medal-programs/america-the-beautiful-quarters/effigy-mounds-national-monument