Carnegie Museum of Natural History collects and cares for specimens and artifacts that document the history of life and human cultures. Today its dinosaur collection includes the world's largest collection of Jurassic dinosaurs and its Dinosaurs in Their Time exhibition offers the third largest collection of mounted, displayed dinosaurs in the United States (behind the Smithsonian's National Museum of Natural History and the American Museum of Natural History). Other major exhibits include Hillman Hall of Minerals and Gems, Alcoa Foundation Hall of American Indians, Polar World: Wyckoff Hall of Arctic Life, Walton Hall of Ancient Egypt, Benedum Hall of Geology, and Powdermill Nature Reserve, established by the museum in 1956 to serve as a field station for long-term studies of natural populations.