Brookfield Zoo, also known as the Chicago Zoological Park, is a zoo located in the Chicago suburb of Brookfield, Illinois. It houses around 450 species of animals in an area of . It opened on July 1, 1934, and quickly gained international recognition for using moats and ditches instead of cages to separate animals from visitors and from other animals. The zoo was also the first in America to exhibit giant pandas, one of which (Su Lin) has been taxidermied and put on display in Chicago's Field Museum of Natural History. In 1960, Brookfield Zoo built the nation's first fully indoor dolphin exhibit, and in the 1980s, the zoo introduced Tropic World, the first fully indoor rainforest simulation and the then-largest indoor zoo exhibit in the world. The Brookfield Zoo is owned by the Cook County Forest Preserve District and managed by the Chicago Zoological Society. The society sponsors numerous research and conservation efforts globally. History In 1919, Edith Rockefeller McCormick donated land she had received from her father as a wedding gift to the Cook County Forest Preserve District for development as a zoological garden. The district added to that plot and in 1921, the Chicago Zoological Society was established. Serious construction did not begin until 1926, after a zoo tax was approved. Construction slowed during the Great Depression, but regained momentum by late 1931. Construction went on at an increased pace and the zoo opened on July 1, 1934. By the end of September 1934, over one million people had visited the new zoo; the four millionth visitor was just two years later. The 1950s saw the addition of a veterinary hospital, a children's zoo, and the famous central fountain. 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. During the zoo's early decades, a narrow-gauge railroad existed, which carried guests around the outer perimeter of the park from the North Gate to the old Seven Seas dolphin habitat on the park's south end. Bison lived on a small prairie on the west end of the park and