I was there for a couple of conventions, the last of which was in August 2001. I spent a little while online with some fellow attendees on the afternoon of 9/11, everyone was worried about the hotel staff because they'd been so nice. Someone asked if the hotel could have escaped major damage somehow, and I had to tell them No, there is absolutely no possibility of that; the hotel was right down at the base of the two towers and would have been completely flattened during their collapse. (I was right, but even I was shocked when the pictures came out, and there was only the remnant of one little corner left standing)
I got a lot of resistance to that idea; they couldn't comprehend the scale of the damage, even though those people had all been there in person three weeks earlier, and had all just seen the towers fall on television. It was my first experience with that, but it turned out to be a common reaction. I guess it's because the TV images from the air couldn't really convey the violence of the event, or the force with which those towers fell.
This picture from the ground shows what happened very well, though. This is from the photographer who was unfortunately killed shortly after the photo was taken, when the North tower fell.
Which building is it - the bluish color one in the foreground, or the gray tinted one in the backgroud ..??