zoological garden in Rotterdam, Neth., that was opened in 1887 by a private zoological society. It was essentially the outgrowth of the private collection of two railway workers who kept exotic animals as a hobby. Because of the need for additional space, the zoo was reconstructed in 1938 at its present 17-hectare (42-acre) site in the Blijdorp district of Rotterdam. The centre of the zoo is the Riviera Hall. The main hall of the building houses a collection of small mammals, birds, and fishes, while the zoo's other sections hold elephants, great apes, and tropical birds, including the world's finest collection of birds-of-paradise. The zoo specializes in South Asian species and has bred more than 500 Bengal, Sumatran, and Siberian tigers—a number unmatched by any other zoo. It also had the first group of orangutan that bred regularly in captivity.