Giant City State Park in southern Illinois spans 4,000 acres across Jackson and Union counties and became a state park after Illinois acquired more than 1,100 acres in 1927. Known as a National Natural Landmark and a major outdoor destination, it offers hiking, horseback riding, picnicking, rock climbing, and trails including Giant City Nature Trail, Red Cedar Trail, Trillium Trail, and the River to River Trail. Its lodge and cabins, largely built by the Civilian Conservation Corps in the 1930s, became a notable New Deal-era complex later listed on the National Register of Historic Places. The park also contains the prehistoric Giant City Stone Fort Site, adding archaeological importance to its natural and architectural significance.