The Bronx Zoo is a zoo within Bronx Park in the Bronx, New York. It is one of the largest zoos in the United States by area and is the largest metropolitan zoo in the United States by area, comprising 265 acres (107 ha) of park lands and naturalistic habitats separated by the Bronx River. On average, the zoo has 2.15 million visitors each year as of 2009. The zoo's original permanent buildings, known as Astor Court, were designed as a series of Beaux-Arts pavilions grouped around the large circular sea lion pool. The Rainey Memorial Gates were designed by sculptor Paul Manship in 1934 and listed on the National Register of Historic Places in 1972.