In late October of last year at 5438 N. Clark Street in Andersonville, a hidden ghost sign that has existed for nearly a century was once again revealed. The building that was torn down had been completely protecting it from the elements since the 1920s, leaving the sign amazingly well-preserved.
The Andersonville Chamber of Commerce and Room Service Chicago found this vintage photo taken in 1916 when the sign was brand new. The original is online in the Chicago Daily News archives at the Library of Congress website. The original negative can be requested at the Chicago History Museum.
Its visible days are numbered as a new condo building and may cover it up again, although the ACoC has confirmed they have been in contact with the building's owner about preserving it. You can contact the 40th Ward to inquire about preservation.
UPDATE (August 1, 2013): After not being cared for for nearly a century, the wall the sign was on has been tuck-pointed. As a result, the sign has been mostly removed. As the wall will not be visible when the condos next door are completed, it does not appear the sign will be restored.