One of the most iconic photographs in history, shot in 1932 during the construction of New York’s Rockefeller Center, “Lunch on a Beam” remains shrouded in mystery: 84 years on, we still don’t know who exactly was depicted in the photo, and even the photographer’s identity is disputed. But that only makes it more interesting. No one has gotten closer to the answer than Christine Roussel, Rockefeller Center’s archivist, who has exhaustively researched the history of the complex and the photo. Listen to the Unfrozen interview.