“So I guess you’d like to know how high you are?” says my guide Alanna. Yes, I suppose; technically, I’d like to know. But in some sense, it doesn’t really seem to matter at this very moment. As I take my first steps out of the EdgeWalk Summit Room of Toronto’s CN Tower onto the 1.5-metre-wide platform that circles the top of the building’s 360 restaurant, it’s obvious we’re … choose-your-favourite-expletive high. Attached to the tower by only an overhead safety rail via a trolley and harness system, it’s hard to believe that even the most seasoned of adrenaline junkies wouldn’t experience at least the slightest of butterflies. This was my first time in a safety harness, and I sure did.

We are, formally, 356 metres (116 storeys) high, looking down on all of Toronto, from what must be the best view in the city. It’s a sunny, virtually cloudless August morning (EdgeWalk’s third birthday, coincidentally), so visibility is superb. As we begin the 150-metre circle around the tower, planes are landing and taking off at Billy Bishop Toronto City Airport on the Toronto Islands to the south, a float plane is taxiing on Lake Ontario nearby, trains chug into Union Station and traffic zooms along the Gardiner Expressway — all looking like miniature models from this height. All these landmarks and more are expertly pointed out by Alanna.

Canadian Geographic Editor Aaron Kylie hangs out at the CN Tower's EdgeWalk in Toronto. (Photo: Courtesy of CN Tower's EdgeWalk.)

I don’t have long to marvel at the view, however, as she suggests we jump right into the first “activity” of the walk. Called “Toes over Toronto,” the exercise is basic, though far more nerve-wracking than those first steps out of the building: simply dangle your toes out over the edge of the platform. I do so tentatively, then look down. Gulp. And that’s enough of that for me.

Lest I get the chance to dwell on what just happened, Alanna launches me into activity number two, where I lean back out over the city. This, too, is easy enough to execute, but requires a certain amount of confidence in your harness. The hardest part? Looking up at the top 200 metres of the tower — still the tallest in the country almost 40 years after its construction. It’s dizzying. (Even more so on a day when clouds are floating by, says Alanna, who notes that this has the effect of making the tower’s tip look like it’s moving.) Alanna says we’ll try each activity again later during the walk, and that I’ll find they get easier. Here’s hoping.

Having leaned out over the city, continuing along the rail-less platform to the eastern view now feels like a walk in the park. We stop at an eastern vantage and Alanna continues her guided tour of city landmarks — most interesting tidbit from here: we’re one metre higher than the communication tower on the top of the 72-storey First Canadian Place, the city’s and the nation’s tallest building. And it’s from this viewpoint that Alanna launches me into the third activity of the walk: the Superman pose. With rope harness against my shoulder I lean straight out on tippy toes just inches from the platform edge with arms outstretched above my head. As promised, performing this feat is far less scary than the first two.

The tour around the tower continues for a total of 30 minutes, with stops at northern and western vantages, too. Once past my initial apprehension, I found the EdgeWalk surprisingly peaceful, and forgot I was harnessed to a track above my head. The clear conditions with virtually no wind were extremely comfortable. There was no noise from the city below. And exploring the city’s landmarks from on high was fun — like picking out buildings from a satellite view in Google Maps. And, as promised, subsequent activities became easier, and, increasingly enjoyable. At our last stop, I chatted with Alanna for what seemed like minutes as I dangled over the Rogers Centre, which is next door to the tower’s base.

As Alanna concluded the tour, I was left wanting more. Indeed, it wasn’t until the end of this Guinness World Record-holding “World’s Highest External Walk on a Building” that I wanted to know just how high it was. I had grown so accustomed to the height, it had, in a sense, ceased to matter.

The EdgeWalk at Toronto’s CN Tower runs seven days a week from April to November. Two or three 30-minute walks, in groups of six, run every hour throughout the day depending on daylight hours, and in all weather conditions except for electrical storms, high winds or other extreme weather. The total 1.5-hour experience (including briefing and prep) costs $175 per person, which includes keepsake video, photos, certificate of achievement and CN Tower general admission.