Poverty Point National Monument, national monument authorized in 1988. Located in northeastern Louisiana, the site commemorates the Native American culture of the Mississippi River Valley between 1700 and 700 bc. The area includes the largest prehistoric earthworks in North America and features circular ceremonial mounds and concentric ridges. The bird-shaped Poverty Point Mound is the largest of the ceremonial mounds. It is about 210 to 240 m (about 700 to 800 ft) wide at its base and about 20 m (about 70 ft) high. Stone tools, cooking utensils, clay balls, and beads have also been found at the site. The monument is currently a state commemorative site and is managed by the state of Louisiana. Area, 369 hectares (911 acres).