There are all sorts of sci-fi engineering possibilities, but you're talking thousands of human lives here. I've been thinking for the last few days that this is a question that's bound to emerge. And the answer in my mind is that building 100-story buildings just ain't a good idea. Too many people too far off the ground to get them down and out safely in the case of an event such as this.

PLUS it presents an obvious target for such an attack. The reason the WTC and Manhattan were selected was the opportunity to kill as many people as possible with just two missiles. And now, horrifying as it seems, any group looking to build such a structure must consider how attractive a target it will make. In military-think, it's a lot like the decline in prominence of the battleship. Battleships lost their position as the supreme weapons of military might when it became clear that you could sink one with a missile or two from twenty or thirty miles away... a very expensive loss in every possible way.

I work on the 19th floor of a building in uptown Ottawa, which has been evacuated a number of times since I've worked there. (But not since before Sept 11). One night we were evacuated 4 times, cause the alarm kept going off in the extreme heat & humidity. I work the night shift, and our floor is the ONLY one that's full at that time--but the stairwell is completely full of people for 10 minutes or so as we went down it again and again...personally I think this is plenty high up.

It's a peculiarity of urban planning that in our city, being the capital, for many years no building was permitted to be built higher than the Peace Tower (the center tower of the Parliament Buildings, our magnificent if anachronistic late-Gothic seat of government). So there's nothing more than abour 26 stories in the uptown area, which is fine with me.

The proponents of urban-density are going to have to rethink the benefits on a broader cost-benefit sheet.

Willie-O