CN Tower – The History of Toronto’s Most Iconic Structure

2020 - The CN Tower
2020 – The CN Tower

If there was one symbol or building that signified Toronto, or even Canada, the CN Tower would be it. Located at 290 Bremner Blvd, between Lake Shore Blvd W and Front St W in Toronto, the TV and radio communication tower can be seen from miles around. Even from the other side of Lake Ontario on a clear day.

Construction of What Was Once the Tallest Structure in the World

1974 - CN Tower during construction
1974 – CN Tower during construction (City of Toronto Archives, Fonds 124, File 8, Item 66)

Building began by Canadian National (railway) on this engineering wonder in 1973. The tower was partially built for practicality. In the 1960s, Toronto was experiencing a skyscraper construction boom which caused some major communications issues. Signals from the existing radio and TV communications towers were bouncing off the tall buildings causing poor reception for locals.

In early 1973, workers removed 56 metric tonnes of earth and shale to start the foundation. The concrete shaft has a six-sided core with three support legs and within 8 months, it stood 335 m or 1,100 ft high. That portion of the tower was already the tallest structure in the City.

In the summer of 1974, work began on the 7-storey tower sphere. It would one day be the observation areas and revolving restaurant. In March 1975, the antenna was ready to be added. Olga, a huge Sikorsky helicopter, was flown in to both remove the massive construction crane then lift the 44 pieces of antenna into place. Just one month later, the tower was complete.

Completion of the CN Tower

The CN Tower took 40 months with more than 1,500 brave people working 24 hours a day and 5 days a week to complete. The architecture marvel opened to the public in June 1976.

There are 40,524 cubic metres or 53,000 cubic yards volume of concrete, 998 km or 620 miles of post-tensioned steel, 4,535 metric tones or 5,000 tons of reinforcing steel and 544 metric tons or 600 tons of structural steel in CN Tower. It weighs 117,910 metric tonnes or 130,000 tons and cost $63 million to build.

For over 30 years, it was the tallest freestanding structure in the world at 533.33 m or 1,815 ft 5 inches. TV and FM radio reception were much better after that.

Lightning & the Tower

2015 - CN Tower being struck by lightning
2015 – CN Tower being struck by lightning

Did you know that the CN Tower gets struck by lightning approximately 75 times every year? To protect the tower, there are copper strips that run the full length of the structure along with huge grounding rods below it. When lightning strikes, electricity is transmitted through the copper wire and is then diffused into the ground by way of the rods.

Wind Resistance & the Tower

Engineers have designed the CN Tower so that it could weather the incredible force of winds which can come from all directions and at different intensities.

The legs of the triangular-based tower tapper as they rise towards the Observation pod. Depending on the direction of the wind, the shape allows the wind to either split and deflect or reduces its force.

Tightened steel cables run inside the full length of the legs of the concrete structure. These cables allow the tower to be strong yet flexible. During high winds, the Observation Deck can sway up to 22.9 cm or 9 inches while the Sky Pod can sway nearly 50 cm or 19.6 inches. In the antenna, there are two weighted rings. These heavyweights counteract the sway by resisting the push of the wind from various directions.

The #1 Attraction in Toronto

2020 - A view from the base of the CN Tower
2020 – A view from the base of the CN Tower

Today, over 1.5 million people from around the globe visit our incredible attraction that defines the City’s skyline. Along with the observation decks, the CN Tower is home to the EdgeWalk, Glass Floor, SkyPod, LookOut, high-speed elevators, the 360 Restaurant, shopping and much more.

Did You Know?

  • At 9:52 am on March 31, 1975, the CN Tower became the World’s Tallest Freestanding Structure. When the antenna was completed three days later, the height was 533.33 m or 1,815 ft 5 inches. It held this distinction until 2007. It was surpassed by the Burj Khalifa skyscraper (in Dubai) which stands at 829.8 m or 2,722 ft.
  • When Olga the helicopter was about to remove the massive construction crane (which was used day and night during the 4-year construction), a tragedy was narrowly averted. Olga was taking down the first piece of the boom when the crane shifted which twisted and seized the supporting bolts. Olga was basically tethered to the tower, 1500 feet in the air with only 50 minutes of fuel. Plus, the crane operator was still inside. Steel workers organized and rushed up to burn the bolts off to free the crane. The 12-minute job turned into 30+ minutes. Olga safely landed with 14 minutes of fuel remaining. All of Olga’s manoeuvres after this went perfectly.
  • There’s a time capsule inside the tower wall on the LookOut Level. To commemorate grand opening day, October 2, 1976, the contents include a letter from Prime Minister Pierre Trudeau, daily newspapers (Toronto Sun, Toronto Star and the Globe and Mail) and letters from school children along with Canadian bills and coins. The time capsule is scheduled to be open in 2076.
  • The Glass Floor, the first of it’s kind, was installed in 1994 and is 342 m or 1,122 ft above the ground.
  • In 1995, the CN Tower became one of the Seven Wonders of the Modern World by the American Society of Civil Engineers. It holds this designation with the Empire State Building in New York City and the Golden Gate Bridge in San Francisco, to name a few.
  • In 2007, programmable LED lighting was installed on the exterior. The CN Tower light’s up Toronto’s skyline in vivid colours and mark important events, both happy and sad.
  • Since 2011, EdgeWalk has been thrilling those adventurous enough to be harnessed outside on the edge, 116 storeys above the ground.
  • It takes 72 minutes for the 360 Restaurant to revolve once.
  • The most photographed structure in Toronto is the CN Tower, with the second being the Gooderham Building.

CN Tower Photos

2020 - CN Tower and Toronto's skyline from Centre Island
2020 – CN Tower and Toronto’s skyline from Centre Island
1975 - CN Tower during construction with Sikorsky Helicopter lifting piece
1975 – CN Tower during construction with Sikorsky Helicopter lifting piece (City of Toronto Archives, Fonds 1526, File 47, Item 24)
2020 - A view from the base of the tower
2020 – A view from the base of the tower
1973 - CN Tower construction, looking west from Yonge & Front Sts
1973 – CN Tower construction, looking west from Yonge & Front Sts (City of Toronto Archives, Fonds 1526, File 60, Item 15)
1975 - CN Tower during construction with Sikorsky Helicopter lifting piece
1975 – CN Tower during construction with Sikorsky Helicopter lifting piece (City of Toronto Archives, Fonds 1526, File 47, Item 28)
1975 - View of CN Tower & Eaton Centre construction from Yonge & Shuter Sts
1975 – View of CN Tower & Eaton Centre construction from Yonge & Shuter Sts (City of Toronto Archives, Fonds 1526, File 47, Item 42)
1974 - CN Tower during construction and Waterfront, looking northwest
1974 – CN Tower during construction and Waterfront, looking northwest (City of Toronto Archives, Series 1465, File 240, Item 91)
1974 - CN Tower during construction
1974 – CN Tower during construction (City of Toronto Archives, Fonds 124, File 8, Item 66)
1974 - CN Tower during construction and Union Station
1974 – CN Tower during construction and Union Station (City of Toronto Archives, Fonds 1526, File 47, Item 5)
1974 - CN Tower during construction, looking northeast
1974 – CN Tower during construction, looking northeast (City of Toronto Archives, Series 1465, File 751, Item 20)
1973 - CN Tower during construction, view from King St W, in front of the Royal Alex
1973 – CN Tower during construction, view from King St W, in front of the Royal Alex (City of Toronto Archives, Fonds 1526, File 47, Item 1)
2019 - CN Tower and Rogers Centre, looking northeast from Lake Shore Blvd W
2019 – CN Tower and Rogers Centre, looking northeast from Lake Shore Blvd W
2015 - CN Tower being struck by lightning
2015 – CN Tower being struck by lightning
1977 - Gooderham Building and CN Tower, looking west from Church & Front Sts
1977 – Gooderham Building and CN Tower, looking west from Church & Front Sts (City of Toronto Archives, Fonds 1526, File 47, Item 66)
1973 - CN Tower construction, view from King St W & Widmer St looking south past houses on Mercer St
1973 – CN Tower construction, view from King St W & Widmer St looking south past houses on Mercer St (City of Toronto Archives, Fonds 1526, File 47, Item 2)
2020 - The CN Tower
2020 – The CN Tower
1980 - CN Tower and skyline from Broadview Ave, overlooking Riverside Park East
1980 – CN Tower and skyline from Broadview Ave, overlooking Riverside Park East (City of Toronto Archives, Fonds 1526, File 47, Item 80)
1974 - Scadding House. Rectory, Church of the Holy Trinity and view of excavation of the Eaton Centre with construction of CN Tower, looking southwest
1974 – Scadding House. Rectory, Church of the Holy Trinity and view of excavation of the Eaton Centre with construction of CN Tower, looking southwest (City of Toronto Archives, Fonds 1526, File 83, Item 53)
1976 - HMCS Haida at Ontario Place with CN Tower
1976 – HMCS Haida at Ontario Place with CN Tower (City of Toronto Archives, Fonds 124, File 9, Item 42)
1975/87 - View of Toronto skyline and Island Ferry
1975/87 – View of Toronto skyline and Island Ferry (City of Toronto Archives, Series 1465, File 726, Item 18)
1976/85 - Aerial view of downtown Toronto and Island Airport, looking northeast
1976/85 – Aerial view of downtown Toronto and Island Airport, looking northeast (City of Toronto Archives, Series 1465, File 745, Item 15)
1977/98 - View of CN Tower from the CNE
1977/98 – View of CN Tower from the CNE (City of Toronto Archives, Series 1465, File 56, Item 5)
1984 - View of CN Tower, Canada Malting and Zawisza Czarny ship on the Waterfront
1984 – View of CN Tower, Canada Malting and Zawisza Czarny ship on the Waterfront (City of Toronto Archives, Fonds 1526, File 113, Item 9)
2019 - CN Tower Tour sign
2019 – CN Tower Tour sign
1988/92 - Toronto skyline, looking west
1988/92 – Toronto skyline, looking west (City of Toronto Archives, Series 1465, File 669, Item 127)
1975 - CN Tower during construction with Sikorsky Helicopter lifting piece
1975 – CN Tower during construction with Sikorsky Helicopter lifting piece (City of Toronto Archives, Fonds 124, File 8, ID 69)
2009 - View of CN Tower from Beaconsfield laneway
2009 – View of CN Tower from Beaconsfield laneway (City of Toronto Archives, Fonds 485, Series 2341, File 1, Item 31)
1973 - CN Tower construction and Skyline from Parliament St, south of Front St
1973 – CN Tower construction and Skyline from Parliament St, south of Front St (City of Toronto Archives, Fonds 1526, File 47, Item 4)
2020 - The Toronto skyline from Trillium Park
2020 – The Toronto skyline from Trillium Park
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