What was the original purpose of the Empire State Building's spire?

The Empire State Building’s spire was originally intended to serve as a mooring mast for airships.

The 1931 skyscraper was designed during an era when zeppelins and dirigibles were promoted as the future of long-distance travel. Architects planned for passengers to check in on the 86th floor, ride elevators upward, and board airships near the top of the tower.

The plan proved impractical. Strong winds, turbulent air currents around Manhattan’s skyscrapers, and the difficulty of safely stabilizing an airship made regular docking too dangerous. A small airship briefly made contact with the mast in September 1931, but the building never became a working airship terminal.

The spire later became useful as a broadcasting structure. That is why “radio antenna” can sound plausible, but it describes a later use rather than the spire’s original purpose. The observation decks, meanwhile, are located lower in the building.