William Van Alen secretly built a spire in Chrysler Building

In the late 1920s, architect William Van Alen and his former business partner H. Craig Severance, now bitter rivals after an acrimonious split, were racing to design New York's tallest skyscraper — Van Alen for the Chrysler Building, Severance for 40 Wall Street. Because both buildings' heights were public information as construction progressed, either architect could simply add height to reclaim the lead the moment the other's final number became known, making an openly declared final height a target the rival could always beat.

Van Alen filed public building permits understating the Chrysler Building's true final height, while secretly having his construction crews assemble a 125-foot steel spire in four sections entirely hidden inside the building's own crown structure, invisible from the street and unknown to Severance's team.

After 40 Wall Street topped out at roughly 925 feet in late 1929 and publicly claimed the title of world's tallest building, Van Alen had his crews hoist and rivet the four hidden spire sections together atop the Chrysler Building in just 90 minutes on October 23, 1929 — instantly pushing the building's true height to 1,048 feet and claiming the title before Severance's team could respond in any way.

Filed permits understating true height, hid a spire inside the crown, then riveted it together in 90 minutes after the rival topped out, making the reveal unanswerable.

Assembling the four hidden spire sections in just 90 minutes, only after 40 Wall Street had already topped out and publicly claimed the title of world's tallest building, meant Severance's team had al

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The Chrysler Building became the tallest building in the world upon the spire's assembly, a title it held until the Empire State Building surpassed it roughly a year later — but the maneuver itself is remembered as a decisive, unanswerable move precisely because Severance's team had no opportunity to react once the spire was in place, having already publicly declared victory based on incomplete information about their rival's true plans.