A list of the world's tallest peaks here.
Toronto's CN Tower is 553.33 m [1,815.39 ft]. Mount Everest, more than 16x taller at 8,850 m [29,035 ft], was first sumitted on May 29, 1953 by 34 year old New Zealander Edmund Hillary and 39 year old Nepalese Sherpa Tenzing Norgay.
At 636 m [2,087 ft], the still under construction Burj Dubai skyscraper recently overtook the CN Tower in as the world's tallest man made structure; it is anticipated to eventually reach 800 m. A list of tall man made stuff is here.
Instead of going up, they should go the other way sinking deep, wide shafts into the ground, beaming in natural light via optical fibers and displaying something else where windows would normally be.
Here's a look at how high aircraft fly:
... most passenger jets fly between around 9,448.8 m [31,000 ft] and 11,277.6 m [37,000 ft] depending on their weight and the distance being flown, however the smaller business jets typically operate up to 13,716 m [45,000 ft] and in the case of Concorde it went as high as 15,544.8 m [51,000 ft]. At those kinds of altitudes you can see the curvature of the earth. The reason is that at high altitudes in less dense atmosphere jet engines work more efficiently by burning a lot less fuel and the ground speed of the aircraft is significantly higher.
Just how far out the atmosphere goes is explained here.
