What is it about tall buildings that makes crazy people want to knock them down? I wasn't surprised when I heard the news that someone plotted to attack Chicago's Sears Tower. After all, it is the tallest building in North America and, according to most records, the third tallest building in the world.

I was surprised, however, that the plot to attack Sears Tower did not come from just one crazy guy, but seven people. What are they thinking?

In the News: Seven Men Arrested for Sears Tower Plot

^{Sears Tower Photo © Mary Ann Sullivan, Digital Imaging Project}