The island of Manhattan is connected to the rest of the world through 21 bridges and 15 tunnels. The bridges range in complexity from the comparatively simple Harlem River swing bridges to the grandeur of the Brooklyn Bridge and cover a hundred years of bridge construction technology and social change.
There are numerous sites on the web that cover the history and design of Manhattan bridges, including NYCRoads.com and NYC DOT. The Federal Department of Transportation maintains the National Bridge Inventory.
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