We were driving back to our apartment from Costco and I noticed what I thought to be a plane. Looking closely I noticed it was round

My girlfriend and I had just finished shopping at Costco in the University Village in Chicago. Shortly leaving the store I noticed what I believed to be a plane from a distance. I assumed it was a plane because we see many planes land to OHare and Midway. However, looking more closely at the airplane I noticed that I was round and did not appear to look like a plane. I pointed out the object to my girlfriend while we were driving and she insisted that I record it. I filmed a couple of seconds of the craft before it became obstructed by a building near us. The craft seemed to be pretty far from us but zooming in on the video I noticed that the craft was clearly round. I don’t know if this was a drone or blimp because it appeared to be much larger and going much more fast.