The CN Tower may no longer be the world's tallest freestanding structure (thanks, Burj Dubai), but it's still an impressive attraction—even if it's something that most locals agree is better to visit than to live with.

However you approach Toronto—on an island-airport flight or on the highway—the first thing you see is this slender structure. Glass-walled elevators glide up the 553m (1,814-ft.) tower, first stopping at the 346m-high (1,135-ft.) LookOut level. (The truly fearless can ride up in the vertiginous glass-floored elevator, which the CN Tower opened in 2008.) Walk down one level to experience the Glass Floor, which is great for a dizzying face-plant: Through it, you can see all the way down to street level. Take comfort: The floor won't break. The glass can withstand the weight of 35 adult moose.

Above the LookOut is the world's highest public observation gallery, the SkyPod, 447m (1,467 ft.) above the ground. From here, on a clear day, the sweeping vista stretches across Lake Ontario to the south and across the cityscape to the north. Atop the tower sits a 102m (335-ft.) antenna mast: It took 26 days, with the aid of a giant Sikorsky helicopter, to complete the operation.

For a 35th anniversary celebration, the EdgeWalk opened in summer 2011. An elevated, narrow (1.5m/ 5-ft.) ledge 116 stories above ground, it circles around the perimeter of the tower's main pod and claims to be "the world's highest full circle hands-free walk." Thrill-seekers are locked into harnesses that are attached to a pulley system and then head off for a gravity-defying walk. Definitely not for vertigo sufferers. It also comes with a dizzying fee of $225.