2120 South Michigan Avenue is a legendary address among blues and rock fans. The Rolling Stones even wrote a song about it. It was once the home of Chess Records - the label of Howlin' Wolf, Muddy Waters, and Chuck Berry. Today the two-story building is home to the Blues Heaven Foundation. Earlier this week, First Lady Hillary Clinton visited 2120 as part of an effort called Save America's Treasures. NPR's David Welna reports.