Rockefeller Center sits on the site of the Elgin Botanic Garden, which physician David Hosack opened in 1801 as the country’s first public botanical garden. The 20 acres passed to New York State and then, by 1823, to Columbia University, which kept the land as an investment after moving to Morningside Heights. In 1928 the Metropolitan Opera, outgrowing its home at 39th Street and Broadway, recruited John D. Rockefeller Jr. to back a new opera square. He signed an 87 year lease with Columbia at $3 million a year, with total costs estimated around $250 million. Then the October 1929 crash wiped out the opera’s patrons, and by December the Met withdrew, leaving Rockefeller holding the lease with no tenant.

Rather than walk away, he pivoted in May 1930 to a mass media complex anchored by RCA, NBC, and RKO, designed in Art Deco by the Associated Architects led by Raymond Hood with Harvey Wiley Corbett and Wallace Harrison. The stepped silhouette of 30 Rock came from the 1916 zoning resolution’s setback rules. Publicist Ivy Lee persuaded a reluctant Rockefeller to use the family name in December 1931 to reassure nervous tenants. Crews demolished 228 buildings, displaced about 4,000 tenants, and employed 40,000 to 60,000 workers, with Radio City Music Hall opening in December 1932. By 1944 the complex was 99.7 percent leased, and in 2000 a Tishman Speyer partnership with the Crown family bought it for $1.85 billion.

• A record order of 14 million cubic feet of Indiana limestone placed in December 1931
• Lunch atop a Skyscraper, the famous 1932 photo on 30 Rockefeller Plaza’s steel, staged as promotion
• How a failed underground shopping concourse became the ice rink in 1936
• The Christmas tree tradition started in 1931 by workers who decorated a 20 foot balsam fir with tin cans
• Diego Rivera’s Man at the Crossroads mural, chiseled off after he refused to remove a portrait of Lenin