The Henry Doorly Zoo's "Simmons Aviary" opened in 1983 and is one of the world's largest free-flight aviaries. About 500 birds from all parts of the world occupy the area of the aviary. In this exhibit, visitors see flamingos, ducks, swans, storks, cranes, spoonbills, ibis and egrets. The Aviary is long and rises to at the center. The structure of two-inch nylon mesh is supported by a system of cables and poles. The use of nylon instead of wire is a unique concept.