Few zoos in the United States are older than the San Antonio Zoo, and fewer still sit inside an old limestone quarry. The zoo was founded in 1914, when the city fenced in a portion of the old limestone quarry within Brackenridge Park and began acquiring animals. The quarry's 15-foot-high rock walls provided natural enclosure barriers that made housing large animals far cheaper than building conventional cage structures, and the dramatic bluffs became the backdrop for some of the zoo's most striking exhibits.
In those early years, the collection included a handful of bears, big cats, deer, and exotic birds. Over the following decades, the San Antonio Zoo grew into a major institution housing more than 9,000 animals representing 750 species — one of the larger collections in North America. The zoo has long been a leader in breeding programs for endangered species, including black rhinos, white-naped cranes, and the red-billed curassow.
The old quarry walls are still visible throughout the grounds, giving the zoo a sense of geological drama unusual among American zoos. The San Antonio River's headwaters flow through the northern edge of the property, and during spring floods, the limestone rock faces wear the river's age like fine lines on an old face. Generations of San Antonio children have taken their first exotic animal sightings here.