Irvine Co. is buying Chicago Tower at 300 North LaSalle for $850 Million, or $654 per square foot. That tops the record $840 million paid for 110-story Sears Tower, er, Willis Tower.

 

http://www.bloomberg.com/news/2014-05-19/irvine-co-agrees-to-buy-chicago-tower-for-850-million.html