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CHICAGO — It’s probably the most historic building in Chicago you’ve never seen.  

The oldest building in the Cook County jail complex, the notorious “Division I,” once held Al Capone, hosted a Blues legend and housed the state’s original electric chair.  

It is the oldest building on a 96-acre campus that was once known as the “largest concentration of inmates in the free world.”

The complex is still one of the largest local jails in the country, but the building has been empty for nearly a decade.

The century-old building is in disrepair and it’s being demolished to make way for a recreational area. 

But before the bulldozer’s started, WGN’s Mike Lowe went on one last tour, the last reporter ever inside the walls of the old jail.