Chicago skyscraper to double height

(image from ArchitectureChicago Plus blog)
The Blue Cross-Blue Shield Building in downtown Chicago at 300 East Randolph is going to double its height by adding another building right smack on top of it. According to the ArchitectureChicago Plus blog, The 32-story tower was finished in 1997. But now 25 floors are going to be stacked on top by 2010.
It's great how this building is like a lego block and they can just add another lego block on top of it 10 years later. The Blue Cross building's neighbor, the AON Center is the nation's 3rd tallest building. What would happen if another one was built on top of it? Here's how it would look. Magnificent!
(photoshop work on AON center by spudart.org)
That was so much fun, let's take another image and double the height of the AON Center:
Haha! Double the fun!