The Cincinnati Zoo and Botanical Garden is the second-oldest zoo in the United States, opening in 1875, just 14 months after the Philadelphia Zoo opened on July 1, 1874. It is located in the Avondale neighborhood of Cincinnati, Ohio. It originally began with 64.5 acres in the middle of the city, but has spread into the neighboring blocks and several reserves in Cincinnati's outer suburbs. It was appointed as a National Historic Landmark in 1987.