I am absolutely sure, indeed, that I have mentioned that I am afraid of heights.
I need to get over it.
I was able to go to the top of the Empire State Building easily, I think because I don't feel like I'm going to fall over, all railings are above my center of gravity. Though "the ledge" at Sears Tower is completely enclosed, the visual sensation of potential gravity-assisted exit from the structure made my toes curl up, quite literally, while I was watching the video.
This is indeed geography. Lots of things are.
(link via NPR)