See http://www.cityofchicago.org and then search for “Demolition List 2008”
The building in which the office that Bill Ayers and Barack Obama shared exists is scheduled for demolition by the Planning & Development Dept. of the City of Chicago to make room for a new public park.
Demolition Hold List (2008)
#100252187
Date received: 9/5/08
Address: 115 S. Sangamon
Ward: 2nd
Applicant: Midwest Wrecking
Owner: Chicago Park District
Permit Description: Wreck and remove a 1, 2 and 5-story brick institutional building. Salvage select brick and decorative elements for reuse on site. [as part of city park #542, Sangamon/Adams, to be built on site]
Post 65 link shows some great detail on the building slated for demolition.