The western parts of the Bronx are hillier and are dominated by a series of parallel ridges, running south to north. The West Bronx has older apartment buildings, low income public housing complexes, multifamily homes in its lower income areas as well as larger single family homes in more affluent areas such as Riverdale and Fieldston. It includes New York City's fourth largest park: Van Cortlandt Park along the Westchester-Bronx border. The Grand Concourse, a wide boulevard, runs through it, north to south.