Park Slope is a neighborhood in the western section of Brooklyn, New York City's most populous borough. Park Slope is roughly bounded by Prospect Park West to the east, Fourth Avenue to the west, Park Place to the north and 15th Street to the south, though other definitions are sometimes offered. It takes its name from its location on the western slope of neighboring Prospect Park. Seventh Avenue and Fifth Avenue are its primary commercial streets, while its east-west side streets are populated by many historic brownstones. Park Slope is characterized by its historic buildings, top-rated restaurants, bars, and shops, as well as close access to Prospect Park, the Brooklyn Academy of Music, the Brooklyn Botanic Garden, the Brooklyn Museum, the Brooklyn Conservatory of Music, and the Central Library (as well as the Park Slope branch) of the Brooklyn Public Library system. The neighborhood had a population of about 62,200 as of the 2000 census,resulting in a population density of approximately 68,000/square mile, or approximately 26,000/square kilometer. The neighborhood is well served by the New York City Subway. Several lines have stops in Park Slope. The F train runs along 9th Street, a main shipping street, stopping at Fourth Avenue, Seventh Avenue and 15th Street–Prospect Park/Prospect Park West. The 2 and 3 trains top at Atlantic Avenue, Bergen Street and Grand Army Plaza. The 4 and 5 (during rush hours only) trains stop at Atlantic Avenue. The N, M, and R trains run along Fourth Avenue, stopping at Prospect Avenue, Ninth Street, Union Street and Atlantic Avenue–Pacific Street. The D train also stops at Atlantic Avenue-Pacific Street; and the B Q trains stop there and at Seventh Avenue at Flatbush.