The National Museum of Natural History, part of the Smithsonian Institution, ranks as one of the most visited museums in the world. Two floors of exhibits and two large-format cinemas explore life on earth through clues nature has left behind—among them dinosaur skeletons, prehistoric fossils and glittering gemstones, as well as artifacts of human cultures past and present. The museum's ongoing research programs have resulted in one of the largest, most comprehensive natural history collections in the world.