B63 (New York City bus)

The Fifth Avenue Line is a public transit line in Brooklyn, New York City, United States, running mainly along Fifth Avenue and Atlantic Avenue between Fort Hamilton and Cobble Hill. Originally a streetcar line, it is now the B63 Fifth/Atlantic Avenues bus route, operated by the New York City Transit Authority.

The B63 bus route begins at Shore Road and Fourth Avenue in Fort Hamilton, and heads north on Fourth Avenue, splitting onto Fifth Avenue at 94th Street. Fifth Avenue is followed through Bay Ridge, Sunset Park, and Gowanus to Park Slope, where buses turn northwest on Flatbush Avenue and west on Atlantic Avenue to South Ferry. Along the way, subway connections can be made at Bay Ridge – 95th Street, Fourth Avenue – Ninth Street, and Atlantic Avenue – Barclays Center, as well as the Long Island Rail Road's Atlantic Branch at Atlantic Terminal.