Toronto's CN Tower: No longer number one, but still pretty cool
Most holidays to Canada, or at least for those who don't have a fear of heights, are incomplete without a visit to Toronto's CN Tower.
This engineering marvel may no longer be the world's tallest free-standing structure, as it was for 31 years after it opened to the public in 1976, but the 2010 Book of Guinness World Records still lists it as the world's tallest tower.
The magnificent views of the city and across Lake Ontario from its different observation levels haven't changed. Visibility on a clear day can reach 160 kilometres. 

 
The tower is 553 metres tall at the tip of its communications antenna, and the top sky pod observation level is at 447 metres. If you don't want to go quite that high, you can look 342 metres straight down to the ground through a glass floor.
Elevators with floor to ceiling windows (and one with a glass floor) take you up and down the outside of the tower, so you can get a great perspective on your way to the top and get some last looks as you leave.
If you want to take your time and enjoy a meal during your visit, the revolving 360 Restaurant offers fine dining, and you're sure to find a vintage you like from its world's highest wine cellar. Horizons on the 346-metre Look Out level and the Far Coast Cafe at the tower's base offer other food options.
Visitors can watch a film on the construction of the tower in the Maple Leaf Cinema, or seek thrills in the Himalamazon motion theatre ride. It might be a good idea to take that in before you eat.
A large gift shop featuring a wide array of CN Tower and Canadian collectibles should satiate souvenir seekers.
It's still not official, and it's still a few years away even if it gets the bureaucratic go-ahead, but a large aquarium has been proposed for land around the base of the tower. Combined with the adjacent Rogers Centre, home of the Toronto Blue Jays baseball team and Toronto Argonauts football squad, the addition will make it easy to spend pretty much a full day and night in the vicinity.
The CN Tower is open every day but Christmas from 9 a.m. to 10 p.m. There are a variety of pricing packages, depending on what attractions you want to take in.