The Forest Preserve District of Cook County is a governmental commission in Cook County, Illinois, that owns and manages a network of open spaces, containing forest, prairie, wetland, streams, and lakes, that are mostly set aside as natural areas. Cook County contains Chicago, and is the center of the most densely populated urban metropolitan area in the Midwest. The Forest Preserve lands encompass approximately 70,000 acres (110 sq mi; 280 km2), about 11% of the county, providing open space within its urban surroundings. It contains facilities for recreation, as well as a zoo and a botanic garden.