The Brooklyn Bridge turns 121 today. When it opened, it was double the length of any other suspension bridge. The span's engineer, John Roebling, was killed making the it. His son, Washington Roebling, took over the construction of the bridge and was paralyzed by the bends in the process. The Brooklyn Bridge is an engineering marvel, and ushered in more than a century of even more amazing American building projects--the Panama Canal, the Empire State Building, the Hoover Dam, the Interstate Highway System, the Big Dig.