The Great Mammal Hall, a two-story gallery, some 60 feet long by 40 feet wide, is the most dramatic gallery in the museum, with an arrangement of specimens that includes a full-sized giraffe, a bison, a narwhal, and three whale skeletons suspended from the rafters. Some creatures on display here, such as the Steller’s sea cow, have now become extinct. On the balcony, visitors can find specimens from Harvard's extensive collection of birds from around the world and can closely examine the impressive toothed jaw of a sperm whale and the baleen of a right whale.