The Cincinnati Zoo Historic Structures are a set of historic buildings at the Cincinnati Zoo in Cincinnati, Ohio.They have been listed in the National Register of Historic Places since February 27, 1987.
The second oldest zoo in the United States
, it opened to the public in September 1875. Significant for the antiquity and richness of its collections and for its efforts in the propagation and nurture of rare and endangered species, it was well known as the home of "Martha" the last passenger pigeon.
The Aviary, where she lived, and the original Monkey House and Herbivore House are the zoo's earliest surviving structures.The Aviary, Money House, and Herbivore House are known today as the Passenger Pigeon Memorial, the Reptile House, and the Elephant House, respectively.