What do you think is the best tourist attraction in Chicago?

I'm actually a big fan of The Willis Tower, which used to be the world's tallest building, and used to be called the Sears Tower. At the same time, I like Navy Pier, which has some fun rides and is quite beautiful, and Millennium Park, which is also fantastic on a lovely summer day, such as today :)

So my favorite? Probably Navy Pier, but they're all pretty close to one another, so you don't really have to pick. You can enjoy them all!