The oldest crossing still standing is High Bridge, built in 1848 to carry the Croton Aqueduct from Manhattan to the Bronx over the Harlem River.[6] This bridge was built to carry water to the city as part of the Croton Aqueduct system.Ten bridges and one tunnel serving the city have been awarded some level of landmark status.[6] New York features bridges of many lengths and types, carrying vehicular, bicycle, pedestrian, and subway traffic.The Queens Midtown Tunnel was opened in 1940 to relieve the congestion on the city's bridges.