With the birth of the steel-frame skyscraper in the late nineteenth century came a new breed of man, as bold and untamed as any this country had ever known. These "cowboys of the skies," as one journalist called them, were the structural ironworkers who walked steel beams -- no wider, often, than the face of a hardcover book -- hundreds of feet above ground, to raise the soaring towers and vaulting bridges that so abruptly transformed America in...