America's First Zoo! One of the best laid-out and most animal-packed zoos in the country, the Philadelphia Zoo is set among a charming 42-acre Victorian garden with tree-lined walks, formal shrubbery and animal sculptures. In addition to its animals, the zoo is known for its historic architecture, which includes the country home of William Penn’s grandson, its botanical collections of over 500 plant species, its groundbreaking research and its fine veterinary facilities.