Outside the Rialto TheatreContributed by Davis Dominguez Gallery
The mural is at the southeast corner of the building, 318 E. Congress.
Update (August 2, 2012): Here's a closeup of the sign to the right of the mural. I photographed it on April 4, 2012; the edges are curled and the bottom-right corner is missing. I edited the photo to make the words easier to read. You can click on the sign for a larger view — or, here's an even larger view. It's from muralist Salvador Duran.