During the construction of Rockefeller Center in 1932, a photo was taken of 11 ironworkers taking a break from their arduous labors to eat, drink, smoke and talk to each other.

Because they were sitting on a steel beam dangling perilously some 69 stories in the air with Central Park and the Manhattan skyline in the background, the iconic image would soon sear itself permanently into the country’s subconscious.

But who took the picture called “Lunch atop a Skyscraper,” how was it staged, and who were the guys posing for the camera?

These are the questions which nagged director Sean O’Cualain ever since the day he and his brother saw the famous photo hanging on the wall while hoisting a few a world away in Whelan’s pub in Shanaglish, Ireland. A note next to the stunning snapshot identified a couple of emigrants to America from County Galway, Sonny Glynn (1903-1953) and Matty O’Shaughnessy (1901-1978), as the bookends on the far left and far right of the girder, respectively. That chance encounter in the bar was the source of inspiration for Men at Lunch, an enlightening documentary narrated by Fionnula Flanagan which unearths a cornucopia of factoids about the picture’s previously unheralded subjects.

Perhaps more importantly, the film also tells the greater story of the thousands of ironworkers who built skyscrapers during the Depression, a very dangerous undertaking indeed given the 2 percent annual mortality rate along with a 2 percent permanent disability rate. Still, given the dire state of the economy back then, any able-bodied man was likely happy just to have a $1.50 an hour job, even if it was as thankless as it was treacherous. Plus, perched so close to the heavens, they seemingly enjoyed an elevated social status relative to the working-class men making an honest day’s pay down on street level.

A posthumous testament to the intrepid crew of immigrants who risked their lives in the sky over New York City to erect 30 Rock.

Very Good (3 stars)

Unrated Running time: 67 minutes

Distributor: First Run Features

DVD Extras: Five bonus shorts: The 1929 Crash, Rockefeller Center, Joe Woolhead on September 11, 2001, The Inspiration of ‘Lunch atop a Skyscraper’ and Ric Burns on ‘Lunch atop a Skyscraper.’