The building, which is 2.5 million square feet, straddles the Eisenhower expressway. It went up for auction on Thursday.
People in a Rosemont hotel conference room either had the money or represented someone with enough to buy an iconic Chicago property: the old main post office.
"We have 34,000 facilities in the organization for the other facilities. We always know what the price is because you can appraise them. This one you can't appraise. It's a unique building. There's nothing like it in all America," said Tom Samra, US Postal Service.
The bids started at $300,000. Within minutes the bids were in the millions.
Post office officials say a real estate auction seemed like the way to go as the behemoth building has been for sale for 12 years.
As the auction progressed, the bidding came down to two heavy hitters who threw their millions at the sale like pennies into a fountain.
"You can't get away from the fact there's drama and real time real world valuation going on right here right now," said Rick Levin, auctioneer.
The intensity and stress was palpable and visible as the bids escalated during a half hour of shouting, nods and anxious pauses.
The highest bid was $40 million from bidder 0273.
The winning bidder was International Property Developers North America Inc. They won't talk on camera and won't say exactly what their plans are, but in a statement the company says they want to restore the building to be a focal point of Chicago.
Their statement also says: "The location, visibility and historical significance of the post office in the growth of Chicago as a world class center of transportation, commerce and tourism all dictate that we reenergize the property."
H&H Enterprises of New York was the other big bidder. The company's president told ABC7 $40 million was too much.
"I like this building...too much," said Peihua Li, H & H Enterprises.
Now International Property Developers North America has come up with the $40 million. If all goes as smoothly, the new owner takes over on September 15.