The largest collection of mammals, birds, and reptiles in the world. This municipal zoo, located in San Diego, Calif., U.S., was founded in 1916 and is administered by the Zoological Society of San Diego. It occupies a 40.5-hectare (100-acre) site in Balboa Park. The zoo has about 3,500 animals representing more than 700 species. A noteworthy feature of the zoo is its landscaping. More than 2,500 species of exotic plants are maintained on the grounds, adding atmosphere and frequently providing an element of the natural diet for various animal species. © Janet Aguila Krause