The Willis Tower (formerly the Sears Tower) is a Chicago skyline icon. It was once the tallest building in the world, and it is currently the tallest in the USA.
Visiting the Skydeck on the 103rd floor is a great way to get an overview of this incredible city.
The sprawling metropolis reaches neighbouring states Indiana and Wisconsin, and on a clear day you can actually see four states.
If you have the stomach for it, try walking onto the ledge. It is the strangest sensation to walk on. You know that it is safe, but your mind kicks in and makes you want to grab the nearest wall. Fair enough, considering that you are 1,353 feet high.