The balconies are suspended 1,353 feet in the air and jut out four feet from the building's Skydeck.
Designers say the platforms - collectively dubbed The Ledge - have been purposely designed to make visitors feel as they are floating above the city.
The reward is unobstructed views of Chicago from the building's west side and a heart-stopping vista of the street and Chicago River below - for those brave enough to look straight down.
Whew! Not for the faint of heart (or stomach)!
Finally, this is a slice of pure geeky sweetness:
I have got to get me one of those! :)
Have a great weekend!