Let's go to the Zoo! The Philadelphia Zoo was the first zoo in the United States (opening in 1859), and has become one of the premiere zoos in the world. The zoo is comprised of 42 acres of Victorian gardens of historical architecture, and houses over 1,300 rare and exotic animals from around the world. Features of the zoo include a reptile and amphibian house, a children’s petting zoo, and a “zooballoon” which offers views of the area from 400 feet in the air. view all details