zoological park owned by the city of Cincinnati, Ohio, U.S., and administered in conjunction with the Zoological Society of Cincinnati. It maintains one of the largest animal collections in the United States, with more than 17,000 specimens representing in excess of 500 species. The zoo grounds also serve as a botanical garden containing more than 3,000 varieties of plants from around the world, which are showcased in garden displays and added to the naturalistic settings of the animal exhibits. The zoo once held the record for the most births of lowland gorillas in captivity; other species, including Komodo dragons, Asian elephants, and black rhinoceroses, have also been bred successfully at the zoo. Other outstanding exhibits include those featuring the white Bengal tiger and many species of insects. The zoo's Center for Research of Endangered Wildlife conducts research on a variety of reproductive technologies and in 1995 was responsible for the first successful in vitro fertilization (resulting in a subsequent birth) of a gorilla. Founded in 1875, the Cincinnati Zoo is the second oldest zoo in the United States; it occupies a 75-acre (30-hectare) site within the city and also operates the Mast Farm, a 107-acre (43-hectare) breeding facility in Clermont county.