Sears Tower

As part of a pilot project, the south facing windows of the 56th floor of Chicago's Willis Tower will be replaced with Pythagoras Solar's solar windows.

Standing at 1,450 feet and 110 stories, Sears Tower is the third tallest building in the world and recently added “The Ledge”, a series of glass bays on the 103rd floor that offer visitors unobstructed views of Chicago