Neither the Empire State Building nor the Chrysler Building in New York held their record for the world’s tallest structure for as long as Toronto’s CN Tower did. It was conceived by the Canadian National Railway as partially a vanity project: a radio and television broadcast tower intended to be among the world’s tallest, showing off the industry of Canada in general and of CN in particular. The chosen site for the building was a defunct railroad switching station.

On this day, June 23, in 1976 the Canadian Nation Tower opened to the public, with official opening ceremonies taking place four months later.

At an official height on 1815 ft, the Tower stood as the world’s tallest until 2010, when the Burj Khalifa in Dubai, United Arab Emirates was completed. There was some controversy with the Guinness Book of Records whether it was the world’s tallest “tower” or “free-standing tower” or “building,” but in any case several more towers built since have surpassed CN in height.