The CN Tower was built for television, not tourists. In the late 1960s and early 1970s, new glass skyscrapers like First Canadian Place blocked the rooftop microwave links Toronto relied on and bounced broadcast signals into ghosting and static. The Canadian National Railway set out to build a communication hub taller than anything in the city. Construction began in February 1973 with 56,000 tons of earth removed and a 6.7 meter thick foundation. A hydraulic slip form rose about six meters a day, and engineers kept it true by watching hanging plumb bobs through telescopes with crosshairs. Over 553.3 meters the tower strays from vertical by only 29 millimeters.

A Sikorsky S-64 Skycrane nicknamed Olga flew the 102 meter antenna up in 36 pieces, cutting a six month crane job to three and a half weeks. The design shifted along the way, from a three-pillar tripod to a hexagonal core, and added a higher observation pod nicknamed Bud’s Bubble. Tourism paid off its roughly 63 million Canadian dollar cost in 15 years. It drew stuntmen Dar Robinson and Dan Goodwin, a 2,579 step stair climb record of 7 minutes 52 seconds, the glass floor in 1994, and the EdgeWalk in 2011. It held the world’s tallest freestanding structure title for 32 years until the Burj Khalifa passed it in 2007.

• Dar Robinson’s 1979 parachute jump opened three seconds before impact, and his 1980 jump on a wire decelerator with no parachute
• Falling ice that closed the Gardiner Expressway in 2007 and punctured the Rogers Centre roof in 2018
• The fire safety redundancies officials pointed to after the 2000 fire at Moscow’s Ostankino Tower
• The tower versus building distinction that let Guinness certify it as the tallest freestanding tower after 2007
• Over 1,300 LED lights that change color for events and dim during bird migrations