The Four Seasons Chicago is a luxury hotel located in the midst of Chicago’s upscale shopping district known as the Magnificent Mile at 900 North Michigan. Afternoon Tea is now offered only seasonally in November and December. So I would highly recommend contacting the hotel to confirm dates and times.
The images here are from my earlier visit to the Four Seasons. Since then, menu items have almost certainly changed, but I’m sure you’ll be able to get a feel for their afternoon tea experience nonetheless.