There’s a well-worn bit of New York architectural lore, which holds that the whole of the 1920s and ’30s—the golden age of Art Deco, and by some lights, of the city’s architecture in general—was the accidental residue of an abstruse change in the local building code. As the story goes, the unglamorous-sounding 1916 Zoning Resolution was the law that launched a thousand jazzy fantasies: by mandating a set of height-to-street-width ratios, and restricting towers to 25 percent of lot size, the ordinance obliged architects to introduce setbacks into their skyscraper designs. Meant to prevent the city from becoming a warren of gloomy canyons, the rule helped give rise to the jagged silhouette that distinguishes all of the most beloved landmarks of the era, from the Empire State Building to the Chrysler Building to the towers at Rockefeller Center.
The story is true, for the most part. Thanks to architectural draftsman Hugh Ferris, whose famous massing studies—prompted by the zoning change—helped popularize the so-called “wedding cake” type, the setback tower became a sta…