It opened on July 1, 1934,[4] 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[5]) 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 rain forest simulation and the then-largest indoor zoo exhibit in the world.