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

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2020 - The CN Tower opened to the public in June 1976
2020 – The CN Tower opened to the public in June 1976

If there were 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 experienced a skyscraper construction boom, which caused some significant 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 eight 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 remove the massive construction crane and lift the 44 pieces of the 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 five days a week to complete. The architectural marvel opened to the public in June 1976.

There are 40,524 cubic metres or 53,000 cubic yards of concrete, 998 km or 620 miles of post-tensioned steel, 4,535 metric tonnes 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 was much better after that.

Lightning & the Tower

2015 - CN Tower being struck by lightning
2015 – CN Tower being struck by lightning (iStock/Artist: seb29-531399331)

Did you know that the CN Tower is struck by lightning approximately 75 times yearly? To protect the tower, copper strips 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 then diffused into the ground through the rods.

Wind Resistance & the Tower

Engineers have designed the CN Tower to 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 reduce its force.

Tightened steel cables run inside the entire length of the legs of the concrete structure. These cables allow the tower to be strong yet flexible. The Observation Deck can sway up to 22.9 cm or 9 inches during high winds, 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, which stands 335 m or 1,100 ft high
2020 – A view from the base of the CN Tower, which stands 335 m or 1,100 ft high

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. Steelworkers 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 the 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 its 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 lights up Toronto’s skyline in vivid colours and marks 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 ferry dock on Toronto Island
2020 – CN Tower and Toronto’s skyline from Centre Island ferry dock on Toronto Island
August 18, 1973 – Looking south towards the CN Tower during construction from King St W, in front of the Royal Alex Theatre. Notice the early 1970s Ford Pinto in the centre
August 18, 1973 – Looking south towards the CN Tower during construction from King St W, in front of the Royal Alex Theatre. Notice the early 1970s Ford Pinto in the centre (City of Toronto Archives, Fonds 1526, File 47, Item 1)
September 3, 1973 - Looking southeast from King St W and Widmer St towards the CN Tower construction. Notice the houses once on Mercer St
September 3, 1973 – Looking southeast from King St W and Widmer St towards the CN Tower construction. Notice the houses once on Mercer St (City of Toronto Archives, Fonds 1526, File 47, Item 2)
September 11, 1973 - Looking west from Yonge St and Front St E towards the Dominion Public Building on the left, Union Station in the centre background, the construction of the  CN Tower in the distance and the Gowans Kent Building on the right
September 11, 1973 – Looking west from Yonge St and Front St E towards the Dominion Public Building on the left, Union Station in the centre background, the construction of the CN Tower in the distance and the Gowans Kent Building on the right (City of Toronto Archives, Fonds 1526, File 60, Item 15)
November 14, 1973 – Looking west from Parliament St, south of Front St E towards the CN Tower construction and downtown Toronto
November 14, 1973 – Looking west from Parliament St, south of Front St E towards the CN Tower construction and downtown Toronto (City of Toronto Archives, Fonds 1526, File 47, Item 4)
Circa 1974 - Looking northwest towards the waterfront and downtown Toronto. Notice the CN Tower being constructed on the left
Circa 1974 – Looking northwest towards the waterfront and downtown Toronto. Notice the CN Tower being constructed on the left (City of Toronto Archives, Series 1465, File 240, Item 91)
2020 - A view from the base of the CN Tower, which stands 335 m or 1,100 ft high
2020 – A view from the base of the CN Tower, which stands 335 m or 1,100 ft high
1974 - CN Tower during construction
1974 – CN Tower during construction (City of Toronto Archives, Fonds 124, File 8, Item 66)
August 14, 1974 – Looking southwest towards the Eaton Centre excavation with the Scadding House, Rectory and Church of the Holy Trinity above the dig. In the background, also notice the top of Old City Hall's clock tower and the CN Tower during construction
August 14, 1974 – Looking southwest towards the Eaton Centre excavation with the Scadding House, Rectory and Church of the Holy Trinity above the dig. In the background, also notice the top of Old City Hall’s clock tower and the CN Tower during construction (City of Toronto Archives, Fonds 1526, File 83, Item 53)
1974 - Looking northeast towards the CN Tower during construction and notice the Royal York Hotel in the background on the right
1974 – Looking northeast towards the CN Tower during construction and notice the Royal York Hotel in the background on the right (City of Toronto Archives, Series 1465, File 751, Item 20)
November 26, 1974 - Looking west towards the Union Station and the CN Tower during construction
November 26, 1974 – Looking west towards the Union Station and the CN Tower during construction (City of Toronto Archives, Fonds 1526, File 47, Item 5)
March 23, 1975 – The Sikorsky Helicopter lifting piece of the CN Tower during construction
March 23, 1975 – The Sikorsky Helicopter lifting piece of the CN Tower during construction (City of Toronto Archives, Fonds 1526, File 47, Item 24)
March 23, 1975  - The Sikorsky Helicopter lifting piece of the CN Tower during construction
March 23, 1975 – The Sikorsky Helicopter lifting piece of the CN Tower during construction (City of Toronto Archives, Fonds 1526, File 47, Item 28)
April 16, 1975 – Looking southwest from Yonge St and Shuter St towards the construction of both the CN Tower and Eaton Centre
April 16, 1975 – Looking southwest from Yonge St and Shuter St towards the construction of both the CN Tower and Eaton Centre (City of Toronto Archives, Fonds 1526, File 47, Item 42)
2019 – Looking northeast towards the Rogers Centre and the CN Tower from the Gardiner Expressway near Spadina Ave
2019 – Looking northeast towards the Rogers Centre and the CN Tower from the Gardiner Expressway near Spadina Ave
August 26, 1977  – Looking west from Church St along Front St E towards the Gooderham Building in the right foreground and CN Tower in the background
August 26, 1977 – Looking west from Church St along Front St E towards the Gooderham Building in the right foreground and CN Tower in the background (City of Toronto Archives, Fonds 1526, File 47, Item 66)
2020 - The CN Tower opened to the public in June 1976
2020 – The CN Tower opened to the public in June 1976
April 22, 1980 - Looking southwest towards CN Tower and Toronto skyline from Broadview Ave, overlooking Riverside Park East
April 22, 1980 – Looking southwest towards CN Tower and Toronto skyline from Broadview Ave, overlooking Riverside Park East (City of Toronto Archives, Fonds 1526, File 47, Item 80)
August 1976 - Looking northeast from Ontario Place towards the H.M.C.S. Haida with CN Tower in the background
August 1976 – Looking northeast from Ontario Place towards the H.M.C.S. Haida with CN Tower in the background (City of Toronto Archives, Fonds 124, File 9, Item 42)
Between 1975 and 1987 - View of the Island Ferry, CN Tower and Toronto
Between 1975 and 1987 – View of the Island Ferry, CN Tower and Toronto (City of Toronto Archives, Series 1465, File 726, Item 18)
Between 1976 and 1985 – An aerial view looking northeast of the Island Airport and Toronto skyline
Between 1976 and 1985 – An aerial view looking northeast of the Island Airport and Toronto skyline (City of Toronto Archives, Series 1465, File 745, Item 15)
1995 - Looking east towards the CNE midway and the CN Tower in the background
1995 – Looking east towards the CNE midway and the CN Tower in the background (City of Toronto Archives, Series 1465, File 56, Item 5)
July 7, 1984 - Looking northeast from Lake Ontario towards Toronto's waterfront. Notice the tall ship Zawisza Czarny behind the two sailboats with Canada Malting and the CN Tower in the background
July 7, 1984 – Looking northeast from Lake Ontario towards Toronto’s waterfront. Notice the tall ship Zawisza Czarny behind the two sailboats with Canada Malting and the CN Tower in the background (City of Toronto Archives, Fonds 1526, File 113, Item 9)
2019 - CN Tower Tour sign
2019 – CN Tower Tour sign
Between 1988 and 1992 - Looking west towards the Toronto skyline
Between 1988 and 1992 – Looking west towards the Toronto skyline (City of Toronto Archives, Series 1465, File 669, Item 127)
November 1, 2009 – Looking southeast towards the CN Tower from an east-west laneway in Beaconsfield Village. The laneway is north of Queen St W, off of Fennings St
November 1, 2009 – Looking southeast towards the CN Tower from an east-west laneway in Beaconsfield Village. The laneway is north of Queen St W, off of Fennings St (City of Toronto Archives, Fonds 485, Series 2341, File 1, Item 31)
2015 - CN Tower being struck by lightning
2015 – CN Tower being struck by lightning (iStock/Artist: seb29-531399331)
2020 – Looking northeast towards the CN Tower and the Toronto skyline from Trillium Park
2020 – Looking northeast towards the CN Tower and the Toronto skyline from Trillium Park
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