The Philadelphia Zoo's 42-acre Victorian garden is home to a large and diverse collection of animals, many of them rare and endangered. Cheetahs, hippos, giraffes, and much more make the Zoo Philadelphia's leading family attraction with over 1.2 million visitors in 2015. Like many other Philadelphia landmarks and institutions, the Philadelphia Zoo is an American first and opened its gates in 1874. Known for its advances in animal science, the Zoo has set the standard for exceptional animal care and management, resulting in many longevity records and national and international firsts for endangered species—from the first orangutan and chimpanzee born in the US in the 1920s, to the first giant river otter born in the US in 2004. The Zoo offers a wide range of educational programs and family workshops, special public events, ecotourism travel opportunities, and ADOPT-an-animal programs to engage audiences and move them to conservation action. The Zoo is the recipient of a 2014 Center Advancement grant, which supported the expansion of its innovative animal trails system and a pilot way-finding app. A 2016 grant will support the Zoo's discovery process to explore how it can leverage its collection of animals and staff expertise to encourage visitors to become advocates for animals and nature.