The 1950s saw the addition of a veterinary hospital,[10] a children's zoo,[11] and the famous central fountain.[12] The zoo went through a decline in the 1960s until a large bond issue from the Forest Preserve District, close attention to zoo governance, and visitor services saw the zoo recreate itself as one of the nation's best. Tropic World, the then-largest indoor zoo exhibit in the world, was designed by French architect Pierre Venoa and opened in three phases (Africa, Asia, and South America) between 1982 and 1984.[13]