Which world's fair in 1893 featured Tesla's alternating current lighting system?

The 1893 World's Columbian Exposition featured Tesla's alternating-current lighting system. Held in Chicago, the fair became one of the most important public demonstrations of Nikola Tesla's AC technology and Westinghouse Electric's power system.

Westinghouse won the contract to illuminate the exposition after underbidding General Electric, which proposed using Thomas Edison's direct-current system. The Westinghouse installation used Tesla's polyphase AC patents, generators, transformers, motors, and thousands of incandescent lamps. It showed that AC electricity could be generated, transmitted, and distributed efficiently over useful distances.

Tesla also appeared at the fair and demonstrated induction motors, rotating magnetic fields, and wireless lighting in a darkened room. His famous Egg of Columbus display used a rotating magnetic field to spin a copper egg upright. The fair is therefore often associated with the victory of AC in the War of the Currents, although the practical achievement involved Westinghouse engineers and many other contributors as well as Tesla.