After reviewing bids from potential tenants, due Sept. 14, it's decision time for the seller, Chicago-based Nebel Inc., as well as would-be purchasers. Will the foundation sign the best lease deal, keep the property, or pass the lease to a new owner? As for buyers, are they looking to take over a fully-leased building, use it themselves, or redevelop the 93-year-old West Loop building a block south of the Skybridge development?

"Because the property has such a wide array of use options, it is difficult to name its value," explains Frank Diliberto, president and chief executive officer of the Oak Brook-based auction company. "The auction will define value through competitive bidding by buyers or tenants with a variety of ideas for the property."

With a 99-year lease expiring this year, MB Financial is moving across the street to 800 W. Madison St.