5. The London Zoo
Location: London, England, United Kingdom
Number of Animal Species: 806
Number of Animals: 19,178
Notable Species: Komodo dragons, pigmy hippopotamus, red kangaroos, Galápagos giant tortoises, Sumatran tigers and various butterfly species.
Opening: 1828
Features: The oldest scientific zoo in the world. Launched the Tiger S.O.S. program to help save the Sumatran tiger, housed the only living quagga before its extinction.
Size: 36 acres