When it opened its gates in 1899, 843 animals were exhibited in small cages and enclosures. Today, the 265-acre Bronx Zoo, New York City, is the largest metropolitan zoo in the United States. It has more than 4,500 animals, representing more than 600 species, many of which live in outdoor settings designed to re-create their habitats. You're often separated from them by no more than a moat or wall of glass.
