On a clear floor, you can see forever...
...or at least to the street, 1,353 feet below.
The Sears Tower's glass balconies* are certainly breathtaking, but what happens on days when they have to cleaned? Can you imagine a window washer going up there? Suppose then someone has to take them out for awhile?
"No, no... they're there, they're just hard to see. Why would someone remove them? Here, I'll step out and show yooooooooooooooooooooouuuuuuuuuuuuuuu (distant, sickening thud)."
Hopefully, they can just rig one of those remote toy helicopters and a large bottle of Windex.
*Which is better than the DOUI office's air balcony. Fortunately, we're on the first floor.