Few images are more iconic to New York than Lunch Atop A Skyscraper, the September 1932 photograph of eleven iron workers eating lunch on a steel beam suspended above Rockefeller Center. And in the new documentary Men at Lunch, director Sean O. Cualain digs into the history behind the Depression-era photograph, attempting to investigate the identities of the anonymous ironworkers and explain why the image has lingered so long in our city's historical canon.

The film, beautifully narrated by Irish actress Fionnula Flanagan, focuses on the trials and tribulations of New York's immigrant population in the '20s and '30s, many of whom were the steel and ironworkers responsible for anchoring skyscrapers like the RCA building, the under-construction subject of Lunch Atop A Skyscraper. Interviewees ponder the photograph's allure, debating the identity of the photographer—the photo has been credited to Charles Ebbetts at times, but there's been no official confirmation—and noting that many New Yorkers claim the mysterious everyman workers pictured are their own family members. And Irish director O Cualain focuses a lot of attention on the workers who hailed from his native land, even tracking two potential iron workers in the photograph to origins in a small Irish village.

At 78 minutes, the film is too long and too slow for its content, which would have been punchier at a half hour and benefitted from a more focused, linear narrative. But history buffs will appreciate the long look back at the city's steel era, and there are some striking images of skyscrapers here, both classic and new. And there's no question that the photograph is a haunting one—even if it was just one big advertisement for Rockefeller Center.

Men At Lunch is currently playing at Quad Cinema, 34 West 13th Street (212-255-8800, quadcinema.com). It is released by First Run Features.