From Chicago Sun Times:
The silhouette-like image that some believe looked like and might be a sign from the Virgin Mary on a wall beneath the Kennedy Expressway has endured a lot since it was first spotted in 2005.
A vandal once scribbled “Big Lie” over the shape. Skeptics saw it as a watermark with only a coincidental resemblance to the outline of Jesus’ mother, as commonly portrayed. Citing safety as crowds had begun gathering there, public works crews tried covering the image with brown paint. That later was scrubbed away by two employees from a nearby car wash wielding degreasing compound.