Wow, I'd never heard this before:
"There was originally supposed to be two skyscrapers here, which is why it is called John Hancock Center. The second tower would gave been East of the first, but the developers could not wrest the land at 195 East Delaware Place away from the very private Casino Club. The developers sent a letter about the second tower to then-club president Doris Winterbotham. She ignored the letter and the development went forward with only one tower. The letter in question was found in Winterbotham's papers after she died, and was later publicized by the Chicago Tribune."
http://www.chicagoarchitecture.info/...ock_Center.php
We could have had our own version of the World Trade Center in Chicago.