57. Wonder: CN Tower

(For the CN Tower preview, please click here.)

On April 2nd, 1975, a helicopter called Olga flew through the Toronto skies. It was carrying the final piece of a 102-metre-high antenna. Those in charge of the project wanted this moment to be special, and on the antenna was the signatures of thousands of children from the Toronto area. Duly, the final piece was carefully set down upon the rest of the antenna – the CN Tower, in terms of height at least, was complete. And it was the tallest free-standing structure in the world. 

This simple little tale reveals two core truths about the CN Tower. It's very tall - at 553 metres, it remains the 6th tallest today, only being usurped in 2007 by the Burj Khalifa. And it's not an austere, deadly serious construction: it lets children sign the antenna, it calls its helicopters Olga. Add to that the multiple gift shops, the revolving restaurant, the EdgeWalk in which people are able to hang over the edge, the glass floors, the SkyPod, the in-house Maple Leaf Cinema, something horrifying called the Kidzone, and at one time a disco called “Sparkles” (sadly discontinued in 1991, a great loss) and we have an attraction that is firmly rooted in the family-friendly category. One might say a little tacky. Sure, it's technically a telecommunications tower, but tourism is where the money's at. At Canadian $32 (£17.50) for the basic admission, and over 2 million tourists a year, that works out as a lot of money. The little extras add up to a hell of a lot more.

Several architects and engineers were involved in planning the CN Tower, but it's a young American-born one called Ned Baldwin we mostly have to thank for this aspect. The CN Tower is a communications tower, for radio and TV signals to be transmitted across the city, but Baldwin recognised that if you build a big tower, people will want to climb up it. With colleagues, he studied Walt Disney World for crowd control and general management of tourists, and geared the CN Tower similarly. The cynic might say he looked for the best ways to extract as much money from tourists as possible, the less cynical might call it a “maximal entertainment experience”... wait, no, that would be an idiot. The less cynical would say that visiting the CN Tower is more than just looking at a view of Toronto from high up. Regardless, Baldwin was right. The CN Tower is unquestionably Toronto's main tourist attraction, and it was the money from tourism, rather than telecommunications, that paid off the entire C$57 million (equivalent to about £181 million today) costs in just 15 years.

Visiting the CN Tower is therefore a very touristy experience. Danielle and I visited on a late July morning. There was a queue for tickets, but it was minor compared to the epic queue for the neighbouring Ripley's Aquarium Of Canada, which opened last year, and which I guess we have to thank for culling the number of small children we had to share tower space with. There were still a lot – school holidays are always a dangerous time to be a tourist. After another short queue, we shuffled through an area which overlooked a gift shop, which was filled with information about towers around the world and, for some reason, a large multi-coloured moose.

Our photos were then taken against a green screen – for later purchase, if we so chose (we didn't). Already, it was clear this was a tower for all the family, in bright lights and colours and that peculiar sense of daze I usually find associated. These tourist tweaks are pretty common to most North American towers and observation decks, though the CN Tower's seemed a little more kitschy. Visiting this particular Wonder is not a terribly classy experience. After another small queue, we were slotted into an elevator, with a glass front and partial glass floor. There are six such elevators, set into the grooves between the legs of the CN Tower, shuttling tourists back and fore.

The Tower is a vaguely three-legged affair. The central core tower is actually hexagonal, rising in one continuous concrete mass all the way to the SkyPod, which is the little blobby bit near the top (not the much-larger big blob about two-thirds of the way up - that's the Main Pod). A spindly tower like this would fall over quite easily, so three support legs have been positioned equally around the hexagon. The pairs of lifts are placed on the remaining spaces on the hexagon.

This design is a spin-off from the original, shorter idea behind the CN Tower, which was to have three separate pillar-like towers, linked at various stages by bridges. This was soon seen as overly complicated and expensive, so morphed into the single tower we see today. It's a remarkably stable design. It could cope with an earthquake of 8.5 on the Richter Scale - Toronto's largest-ever recorded earthquake was around 5.0. It can also handle winds up to 260 miles per hour, twice that of an average hurricane. Baldwin guesses it would take winds up to 1000 mph to topple it – the highest-ever recorded wind speed on earth was in a tornado, at 301 miles per hour.

The strength and stability are from a combination of anchors, cables, and sheer weight. The CN Tower weighs in a hefty 130,000 tons, which the information boards inside the tower claim is 35 times heavier than the Eiffel Tower but I don't know where they get their maths from as my own calculations make it at about 12 times heavier, as the Eiffel Tower is 11,000 tons. They also cite a very precise 23,214 elephants, which seems to be based on a slightly heavier-than-average 5.6 ton African elephant. I think they missed a trick here. They should have used the weight of an average Asian elephant, which is around 3.5 tons, and would have given them a more impressive 37,143 elephants, which also happens to be pretty much the entire population of Asian elephants in the world. That's a better comparison for them: the CN Tower weights the same as all living Asian elephants put together.

The weight (of the CN Tower, not the elephants) is largely due to concrete. The CN Tower is not a series of blocks or bricks put together, rather it is one solid, continuous piece of concrete. It is a seamless, monolithic structure. This is due to a process developed in the 1920s but taken to extremes by the CN Tower, called slipform. A slipform is a framework, in effect a giant mould, one that is able to self-raise. Concrete is poured in at the top, and the slipform very slowly raises itself. This way, the concrete slowly sets, with the lower concrete setting to become support, and the upper, still setting, concrete being added to by the pouring concrete, and so on. It allows for quick, strong constructions, of what is essentially one colossal slab of concrete. It had never been done on the scale of the CN Tower though. At a rate of 2.5 centimetres every five minutes, the giant slipform was raised, and concrete was poured. In just 8 months the entire concrete structure was built. Including the foundations, the pods, antennae, and everything else, the whole Tower took 1537 workers over 40 months to complete, working 24 hours a day, five days a week. Just five days a week? I guess they all needed their weekends.

Keeping the concrete strong are things called “post tension” cables, which run from all the way to the top to the bottom through the concrete. Rather like elastic bands pulled extremely tight, they keep a constant pressure on the concrete to stop it cracking. Still, all this would be easy to blow over if it was just plonked on the ground, but these cables are anchored to the ground, keeping the tension, and thus the strength of the concrete.

Impressive, but is it pretty? Concrete may be a very useful material, but it is rarely an attractive one. Sadly, it seems to have become wildly popular since the latter half of the 20th Century. Close up, it would take a staunch defender to claim the CN Tower looks particularly nice. I'd go as far to say it's a bit of an eyesore.

Can a Wonder of the World possibly look like this close up? It's sheer 1970s ugliness. But before we jump to condemn it, let's look at some of my other Wonders. The Sydney Opera House looks spectacular as part of its harbour setting, but the tiles and tinted glass look somewhat dated when viewed close. And the Millau Viaduct, one of the most elegant constructions on the planet, is fairly chunky and concrete up close.

The difference might be that the Millau Viaduct is out in the countryside, and is rarely viewed so close. The CN Tower is in the heart of Toronto, and so has thousands of people passing close by daily. Sure, I get it that social housing was built on the cheap and looks just as mundane and concrete as it is because nobody was exactly going to marble-face the block, but the CN Tower is Toronto's and Canada's icon. Maybe a little paint? Something to make it a little less overtly drab up close. Personally, I'd cover it in grass and plants like the green wall next to the Caixa Forum in Madrid. Wouldn't that be something?

But I said not to jump and condemn the CN Tower so quickly, because step away from it, and it makes a lot more sense. It's a true city skyline structure. Standing at the base, looking at the concrete mass towering above isn't really the way to admire the CN Tower. But get the short ferry across to Toronto Islands and suddenly it takes on a whole new shape.

Incredible. I'm not a huge fan of the Toronto skyline – too many boring glass blocks – but the CN Tower stands out brilliantly. You don't have to get the ferry to admire it either. Clearly, it's a gigantic structure, and it can be seen throughout Toronto.

It's true also that viewing it close up, until recently, wasn't really something you'd want to do anyway. For decades, the CN Tower stood alone in an effectively derelict industrial site, almost inaccessibly so. Originally, it was supposed to be part of a huge urban development called the Metro Centre. Every once in a while, Toronto gets itself into a frenzy and goes mad with construction. Our visit happened to be timed during one such phase, and half the city seemed to covered in roadworks, renovations, cranes, and emerging glass skyscrapers. A similar thing happened in the late 1960s to the 1970s. Near the centre of the city is a large area of railways, and the grand plans of the Metro Centre were to build over these tracks with walkways and new buildings. It would cover around 190 acres. It was a bold and ambitious plan, and the city council went with it. Meanwhile the chairman and president of Canadian National – CN – also liked the idea, and wanted to build a tower there. This would be a telecommunications tower to serve the city, as the existing one was too small to cope with the newly emerging skyscrapers of the city which were blocking the signal. He wasn't very demanding – he liked the idea of a revolving restaurant and an observation deck, and plenty of space for the broadcasting equipment, but that was about it. Just make it tall. Plans got enthusiastic – the biggest structure in the world! - and he pushed ahead. Construction began. And then then in 1972, a new council got in. And they didn't like the idea of the Metro Centre, partly because it would involve the destruction of Union Station, one of the few historic buildings to have survived the previous decade of bold and ambitious plans. By 1975, the Metro Centre idea was formally abandoned. But it was too late to stop the CN Tower. It should have been the focal point of Toronto's ambitious modern centre, but instead it was a weird gangly orphan, standing alone in the middle of a railway. For decades it was so isolated that a special pedestrian bridge had to be built for tourists. Baldwin wasn't very happy, writing: "Under such ludicrous circumstances Canadian National would hardly have chosen this location to build.”

Despite looking pretty awful close up, the CN Tower still successfully became Canada's biggest architectural icon, trying its best  to compete with Canada's other cultural icons such as maple syrup, the Canadian flag, mounties, ice hockey, Tim Horton's coffeeshops, and not being American. It does the job of the Eiffel Tower or the Statue of Liberty, by being the city-identifying symbol, albeit not as recognisably as these two famous examples.

The Main Pod, that flying saucer-like section just under two-thirds the way up, gives the CN Tower its characteristic profile, and it's the Main Pod is where most of the action happens: it has the outside observation deck, the glass floor, the revolving restaurant, and a non-revolving cafe, covering three floors. There are seven floors in total, but the rest are used for telecommunications stuff. Likely, the management could make even more money for the tower by evicting the broadcasters and using the space for new attractions, but to do this would be an admission that the CN Tower is purely a tourist space. It's nice to be able to pretend its serving a vital function for the city. Rather like the Empire State Building, in fact. According to one report, the Empire State Building barely breaks even on leasing office space, it might be easier to keep it empty, or turn it into a hotel. The real money is the tourism: something like 4 million people a year paying at least $29 each. But the Empire State Building is more than just a tourist gimmick, it's a real, functioning office building, and to do away with that would diminish the whole appeal. And so it is with the CN Tower.

Despite my promise in my preview, we didn't visit the revolving restaurant – it was lunchtime and only the three-course meal option was available. My sincere apologies: if I ever do a revolving restaurant tour of the world, I promise to return. Likewise, I didn't bother with the cafe – it doesn't revolve, so what's the point? The outside observation deck is alright, but it's so coated in netting that the view of the city is kind of obscured, which seems to defeat the point. Getting a good photo is impossible, as is throwing yourself over the edge. Which I guess is the point - I can't find a single record of any suicides from the CN Tower.

The glass floor is quite fun, although very popular. I'd definitely encourage the CN management to make this bigger.

To be honest, as observation decks go, the CN Tower's is alright, but not great. I'd put it equal with the Empire State Building's, but way behind New York's Rockefeller Center, which is all open air. However, this is just the Main Pod – we'd paid a little extra to visit the SkyPod too. It's the smaller blobby bit above the Main Pod.

Until 2008, at 447 metres the SkyPod was the highest observation deck in the world, until the Shanghai World Financial Center's 474 metres (some of the CN Tower information boards haven't quite caught up with this development yet). It's much better. Glass-encased, the views are less obstructed. And yes, it's really pretty high.

From here, you can get excellent views of the CN Towers' newest attraction/gimmick: the EdgeWalk. I think the photos pretty much say everything that needs to be said.

I know I also promised to do this in my preview, but it costs C$175 to do, and I couldn't really justify the money. Seriously, if I was to do every one of the CN Tower's gimmicks, I'd have had to cut the travels short by months.

The SkyPod is as high as a normal visitor can go, it's just a giant antenna for the remaining hundred metres or so. It's also a lightning rod - the CN Tower gets hit by lightning around 75 times a year. Copper strips on the antenna run down the entire length of the tower, attached to 42 rods buried 6 metres underground, channeling the power safely. It's entirely safe to visit the CN Tower even during the wildest thunderstorm, and an information board inside describes it as a "thrilling experience". I would definitely pay to return during a thunderstorm.

At the entrance of the CN Tower, there is this:

Canada's Wonder of the World. I wouldn't disagree. There is no doubt that this is Canada's most recognised, most iconic structure, whether you like it or not. Therefore, 2007 and being eclipsed by the Burj Khalifa must have hurt. For 31 years, Canada had the honour of hosting the tallest free-standing man-made structure on earth, but suddenly it was ousted, and today finds itself down at 6th position. What merit does the tower still have then? For the Empire State Building, losing its place as tallest building in the world certainly hurt, but was made up for by it being a handsome, classic piece of Art Deco architecture. The Petronas Towers, tallest in the world for six years, remain unique and beautiful twin spires, connected by a bridge as though they are hand-in-hand: they are stunning whether tallest or 100th tallest in the world. But remove the world records from the CN Tower and it's a lot less special. It clings on with battered pride to those it still has: world's tallest wine cellar, world's highest external walk on a building, world's longest metal staircase. But it's shouting at the wind: nobody's listening. It's not an attractive tower, it's just very tall. It looks great as part of a skyline - I'd say that's its Wonder superpower - but close up it's pretty ugly, and visiting it is a fairly tacky experience, albeit harmless fun as most tall structures are. Right now, it looks dated, but most things from the 1970s do - let's see if time matures it.

Time, however, is not necessarily something the CN Tower has, not in spades. The lifespan of all constructions is finite, even though some - the pyramids being the prime example - are solid enough to span thousands of years. Modern buildings need more frequent maintenance to survive. The CN Tower is no exception. In the end, maintenance may not be enough. One of the tower's most vital parts, as mentioned above, are the anchors. They hold the steel post-tension cables tight, giving the concrete its strength. Ned Baldwin gives their estimated lifespan at 300 years- and they can't be replaced. What happens then? In the words of Baldwin: “If you x-ray the anchorages and found corrosion, and you couldn’t engineer a solution, you’d have to take it down. Without [them], the tower would be thrown into tension under high winds and would fall down."

There we have it - the CN Tower isn't forever. What will happen in 300 or so years? If it has to be torn down - rather than fall down - would it be rebuilt? How special will the CN Tower seem in 300 years? A unique piece of world architecture, or an old concrete tower?

Some criteria then.

Size: 553 metres tall, and for 31 years the tallest structure in the world, and still the 6th tallest. It dominates the skyline.

Engineering: An impressive feat, especially making it a continuous concrete structure.

Artistry: From a distance, it is slender and tall and space-age, and an attractive and distinctive addition to the skyline. From close up, it is an ugly concrete tower.

Age/Durability: About 40 years old, and currently looking a bit dated. It's strong, but with an apparently finite lifetime. It's hard to imagine people raving on about it in the year 3014.

Fame/Iconicity: The architectural symbol and icon of Toronto and Canada. This is one of its main strengths: everyone who visits Toronto will at least see the tower, and most will want to visit it.

Context: For years, it was stuck alone in a railway yard. Now, it is part of a modern business district, where it fits in a lot better. A modern tower for a modern city, it definitely suits Toronto.

Back Story: It arose because of a cock-up - it should have been part of a massive downtown development and was too far into construction to stop when the rest of the project was cancelled. Despite these inauspicious beginnings, it quickly became Toronto's symbol - mostly because it is really tall.

Originality/Distinctiveness: Its height makes it stand out, but it doesn't look that different from a lot of other communications towers. Here's just one example, from Berlin, built five years earlier.

Wow Factor: Anything this tall gives an instant hit, whether close up or afar. But it's a superficial kind of wow.

Once, the CN Tower's main selling point was that it was the tallest, now it's just a former-tallest, although for 31 years - a fairly impressive run for the 20th Century. But it's not a heavyweight. I believe cities usually benefit from having some kind of icon, and the CN Tower serves that function well. It doesn't make it a World Wonder though, it just makes it Canada's Wonder. Fittingly then, in global terms, I'd place it in my National Wonders category, just below the more iconic Tower Bridge, but above the very humbling, perfectly-judged, and much more tasteful Thiepval Memorial (which has a case for not really being on this list at all).

The Seven Wonders of the World So Far

1. Taj Mahal

2. Great Wall of China

3. Machu Picchu

4. Easter Island

5. Mont Saint-Michel

6. The Colosseum
7. The Eiffel Tower

Other Wonders

The Millau Viaduct
Angkor Wat

Bagan

Hagia Sophia

Sagrada Familia

Sydney Opera House

Borobudur

Leaning Tower of Pisa

Marvels

Empire State Building

St Peter's Basilica

Chartres Cathedral

The Houses of Parliament and Big Ben

The Alhambra
St Paul's Cathedral

Notre-Dame de Paris
Statue of Liberty

Florence Cathedral

Meteora

The Parthenon

Cristo Redentor
The Palace of Versailles

Carcassonne

Ellora

The Blue Mosque

Akshardham

Petronas Towers

Notable Landmarks (or National Wonders)

The Golden Temple
Amiens Cathedral

Edinburgh Castle

Shwedagon Pagoda

Pont du Gard

Forbidden City

Bodhi Tataung Standing Buddha

Verona Arena

Avignon Papal Palace

Tower Bridge 
CN Tower
Thiepval Memorial
Banaue Rice Terraces

Temple of the Emerald Buddha

Interesting Places

The Sacre-Coeur

Terracotta Army

Leshan Giant Buddha

Marina Bay Sands

Non-essential

Nazca Lines

Agra Fort

Ayutthaya Historic Park

City of Arts and Sciences
Lotus Temple

Three Gorges Dam