You probably already know that the South Loop has a pretty amazing history. From Al Capone's infamous speak easies to the homes of the cities wealthiest and most influential families back in the early 1900s on Prairie Avenue.
The area is also home to the legendary Chess Records (2120 South Michigan Ave.). The story of Chess records was recently made into a Hollywood story called "Cadillac Records" that garnered good reviews, but didn't really bring too much interest to the Chicago blues and rock history or movement. However, Beyonce's rendition of the Eta James' classic At Last has become extremely popular again (not that it wasn't popular to begin with):
Chess Records has also hosted various legends such as Buddy Guy, Koko Taylor, Bo Diddley, Muddy Waters, Chuck Taylor and even the Rolling Stones which imortalized the address by recording an instrumental during their first U.S. Tour in 1964 called "2120 South Michigan Avenue". Here is a cover of that instrumental:
The building is still there and is actually now home to Willie Dixon's Blues Heaven Foundation, which is also a museum of sorts. For more info on the foundation, The Chicago Journal has a good article about it as well information on the History of Chess Records.