Tower celebrates 25 years
26, 2001 the CN Tower, the World's Tallest Building and Free
Standing Structure celebrated its 25th Anniversary. Defining
the Toronto skyline, the CN Tower is Canada's most
recognizable and celebrated icon, an important
telecommunications hub, and the centre of tourism in
height of 1,815 feet or 553 metres, the CN Tower has
maintained its designation as the World's Tallest Building
and Free Standing Structure for a record 25 years. A feat
that has not gone unnoticed. The CN Tower was built in 1976
by Canadian National (CN) who wanted to demonstrate the
strength of Canadian industry by building a tower taller
than any other in the world.
the CN Tower was built, the Ostankino tower, built in Moscow,
was the tallest free-standing structure on the planet, at a
sky-spearing 1,762 feet or 540 metres. So, here on Canadian
soil, officials decide to go for it. To make what would
later be christened the CN Tower, the tallest of the tall.
They added about 100 extra feet - or 30 metres - at a cost
of less than $200,000, says project architect Ned Baldwin,
who was with John Andrews Architects.
construction crews moved in on February 6, 1973, and started
to remove over 56 metric tonnes of earth and shale for the
foundation. Once the foundation was ready, work began on the
CN Tower’s 335 m (1,100ft.) concrete shaft, a hexagonal
core with three curved support arms. This involved pouring
concrete into a massive mold or "slipform". As the
concrete hardened, the slipform, supported by a ring of
climbing jacks powered by hydraulic pressure, moved upwards,
gradually decreasing in size to produce the CN Tower’s
gracefully tapered contour.
months later, the CN Tower’s concrete shaft was the
tallest structure in Toronto and by February 1974, it was
the tallest in Canada. In August 1974, work began on the
seven-story tower sphere that would eventually house the
observation decks and revolving restaurant. The CN Tower
approached completion in March 1975, when Olga, the giant
Russian Sikorsky helicopter flew into the city to lift the
44 pieces of the antenna into place.
2, 1975 when the OLGA helicopter lifted the 44th and final
piece of the CN Tower's antenna into place, the CN Tower
joined the ranks of 17 other great structures that had
previously held the title of World's Tallest Free-Standing
Structure. Ross McWhirter, editor of the Guinness Book of
World Records, was on hand to record the milestone for
history and since then, the CN Tower has received numerous
mentions in the famous book including the World’s Longest
Metal Staircase and most recently, the World’s Highest
Wine Cellar. In 1996, the CN Tower’s classification was
officially changed to the World’s Tallest Building and
then to build the CN Tower was $63 million,
approximately $300 million today. It was an ambitious
project that involved 1,567 workers who worked 24 hours a
day, five days a week for 40 months to completion.
months of construction, the CN Tower was finished on April
2, 1975 and opened to the public on June 26, 1976. Although
less than one year old, it was well on its way to becoming
the country’s most celebrated landmark. Twenty-five years
later, it is the centre of telecommunications for Toronto
serving 16 Canadian television and FM radio stations, the
workplace of up to 550 people throughout the year, and one
of Toronto’s premier entertainment destinations.
the CN Tower was classified as one of the Seven Wonders of
the Modern World by the American Society of Civil Engineers.
The World’s Tallest Building shares this designation with
the Itaipu Dam on the Brazil/Paraguay border, the Golden
Gate Bridge in San Francisco, the Panama Canal, the Chunnel
under the English Channel, the North Sea Protection Works
off the European coast, and the Empire State Building.
the CN Tower opened, Canadians and tourists from around the
world have made the trip to Toronto to celebrate this marvel
of civil engineering. Besides serving as a
telecommunications hub, the CN Tower provides world-class
entertainment and a wide range of unique attractions,
exhibits and food and beverage venues.
years, the CN Tower has supported its vision of Toronto’s
premier entertainment destination by totally renovating and
redesigning 360 Restaurant, building the World’s Highest
Wine Cellar, and adding two new elevators.
CN Tower was created to solve a problem. In the late 1960s,
watching television, there were blurred pictures, caused by
a growing number of high-rise buildings, interfering with
transmission signals. This new super-high tower solved the
CN Tower has 102-metre antenna, which was raised segment by
weight of the tower is 117,910 metric tones.
revolving restaurant sways up to one metre in high
wind. Nicholas Isyumov, 65, knows all about that. He worked
for seven years studying models for the tower and predicting
how it would stand up in the wind.
can sway up to 12 feet (3˝ metres) at the top, but on a
normal day, the motions are much smaller than in a typical
tall building. It’s a very safe place to come,” he says.
Tower has an extensive sprinkler system, a 24-hour
monitoring operation, and two 68,000-litre water reservoirs
at the top of the building. There is also a firehose at the
tower’s base, which can send 2,700 litres of water a
minute to any location.
elevator at the CN Tower runs up the outside of the building
and can be powered by emergency generators.