Dressed in overalls and jackets, wearing work boots and hats, the men lined up five dozen strong on Christmas Eve 1931 for that week’s pay at a Midtown Manhattan construction site. Behind them stood a fine Christmas tree. It had been mounted by the men and draped with the traditional cranberry strings and garlands.

They also decorated it with the foil wrappers from blasting caps, a tool of their trade: dynamiting ancient rock to make way for the modern city. The rubbled ground where they stood would become Rockefeller Center.