Almost exactly twenty years ago in 1992 and within a year of the collapse of the Soviet Union, Mikhail Gorbachev visited Chicago which included walking into the S&P pit, as pictured above, along with visiting the CBOT. The following articles do a better explanation of his trip at the time but they neglect to mention, as the Sun Times did, that Gorbachev finished the day by going to the Hard Rock Cafe in River North so he could meet some typical people. (update, I just read that Gorbachev is back in Chicago today, total coincidence w/this post actually as the photo has been sitting on my desk for a while)
Gorbachev Visits Capitalist World`s Chicago Shrines (Tribune article)
Gorbachev Has Hectic, Backslapping Day at Chicago Exchanges (Reuters article)
Even though I spent a fair amount of time on the floor, with all the dignitaries and famous people the only 'celebrity' I ever saw was the actor who played Greg Brady.
(Hate to admit it but as an 11 yearold when the Iron Curtain fell, my only memory of the era is Jesus Jones' Right Here Right Now video)