The impetus for this fine zoo came from the huge wire mesh "flight cage" built by the Smithsonian Institution to house the US bird exhibit at the 1904 world's fair. the 90-acre zoo also features The Living World education center, with live animals and interactive exhibits on biodiversity and the environment. Invertebrates abound at the Monsanto Insectarium; and the new River's Edge habitat is inhabited by Asian elephants, hippos, cheetahs, black rhinos and other fauna that frequent the world's riverbanks.