Nearly every Chicagoan has experienced the oddity of driving straight through the massive Old Main Post Office taking the Ike downtown. In 1996, the Postal Service moved to a new building across the street, leaving the old building vacant. For the past 20 years, not much has happened there other than the occasional fire from commuter train exhaust and Batman. The current owner, Bill Davies, bought the building from the Postal Service in 2009. Since that time, Mr. Davies has unveiled several proposals for the site (see here, here and here); however, not a single hammer has swung at the property. Last week, Rahm Emanuel announced that the City plans…