The National Zoological Park, commonly known as the National Zoo, is one of the oldest zoos in the United States, and as part of the Smithsonian Institution, does not charge admission. Founded in 1889, its mission is to provide leadership in animal care, science, education, sustainability, and visitor experience. The National Zoo has two campuses. The first is a 163-acre (66 ha) urban park located in northwest Washington, D.C. that is 20 minutes from the National Mall by Metro to the Woodley Park station, or downhill walk from the Cleveland Park station. The other campus is the 3,200-acre (1,300 ha) Smithsonian Conservation Biology Institute (SCBI; formerly known as the Conservation and Research Center) in Front Royal, Virginia. SCBI is a non-public facility devoted to training wildlife professionals in conservation biology and to propagating rare species through natural means and assisted reproduction. The National Zoo is accredited by the Association of Zoos and Aquariums (AZA). Altogether, the two facilities contain 2,000 animals of 400 different species. About one-fifth of them are endangered or threatened. Most species are on exhibit at the Zoo's Rock Creek Park campus. The best known residents are the giant pandas, but the Zoo is also home to…