Before and after original mural was madeCourtesy of Google Street View, we can rewind to March 2011, from the northeast (Stone south of Congress), before the mural was started:
Below is the same view in July 2013. Although the color is washed out, you can see the mural on the sunlit side of the structure:
That structure (a ventilation tower for the parking garage underneath, I believe) had Ben's Bells murals on three sides. Below is a view from the southeast (Broadway at Stone) in May 2015:
This blog has photos of the other two Ben's Bells murals on the structure in Murals being made, part 8 (Kindness, part 3) and Ride on, Tucson.
Original mural being madeNow on to 2012, when the “I am Tucson” mural was being made. Thanks much to Monique from Ben's Bells for collecting and sending the historical photos below. The dates came from data hidden in the photo (which can be wrong if the camera's clock wasn't set correctly).
On August 22, 2012, the mural had been outlined onto the refinished side of the structure: