On Sept. 20, 1932, 11 workers sat on a beam 69 floors above Manhattan during the construction of Rockefeller Center. The photograph of this moment, one of the most famous images of New York, is called “Lunch Atop a Skyscraper” (even though a cigarette and a liquor bottle in the hands of these workmen are as noticeable as any sandwiches).

Opening 81 years to the day after that photograph was taken is “Men at Lunch,” a documentary about the picture’s resonance as a symbol of Everymen and about the mystery of who those men really were.

The film’s narration, by the Irish actress Fionnula Flanagan, is lovely; the details revealed of the photograph are fascinating; and the commentary by historians on how the photograph relates to life during the Depression and to the immigrant experience is illuminating.

Yet the film feels meandering. Not only does it offer a jumble of ideas that aren’t followed through, but it’s also structured oddly. It culminates in the revelation that two of the workers in the picture were possibly from a small Irish village, which seems a detour from the American grandeur and casual bravery on which the film focuses. That the director, Sean O Cualain, is Irish, and that the film was financed partly by the Irish Film Board may explain this emphasis. But a montage of modern construction at the World Trade Center site near the end seems even more off the mark and without thematic connection to what preceded it.