Chicago geography question

I was flying into O’hare airport a few weeks ago and I saw something strange.

If you start at the beach, in the downtown area, there is a big (NFL?) sports stadium, a few miles further back, there is a smaller enclosed stadium (NBA?). Behind that, perhaps two or three miles, there was a park with a very strange gold-topped building. Anyone know what it is? Or was I just hallucinating?

Most likely you refer to the golden-domed Field House at Garfield Park. The football stadium, of course, is Soldier Field and the indoor arena is the United Center.

The gold topped dome is in Garfield Park and IIRC it is or was the administration building for the park system. About 3600 west of downtown.
The old Chicago Stadium, about 2200 west, has been razed to make parking space for a new facility which you mentioned. I didn’t see the second. Last and only time I have been on a flight parallel to Madison street where I could see area I once fequented.

As ever, even the the mearest scraps to go on, the Dope trimuphs.