This is 1920s footage, since remastered and colorized by the Smithsonian Channel, of the ironworkers who built the Chrysler Building and the Empire State Building — men walking narrow steel beams hundreds of feet above Manhattan with no harnesses, no hard hats, no safety net. Many of the workers were Mohawk ironworkers from the Kahnawake reserve near Montreal, known as skywalkers for a balance and nerve the trade came to depend on. Photographer Lewis Hine climbed the steel alongside them to document the same work in stills.