This is a good shot, and you must have gotten it from the southern end of Grant Park. You were lucky it was a clear day because you had gotten a very good shot of the Sears Tower.

In all honesty, I cannot think of anyone locally who refers to the Sears Tower as the "Willis Tower." About the only folks who seem to refer to the Sears Tower as the "Willis" is the news reporters, but I think most newscasts in the area are either out of touch or simply have to do what the corporation who owns them tells them. There are definitely places around the City that have an official name but are still referred to by their original name irregardless of new ownership.