This set of Apple latters was used in the Chicago Apple Corporate Office in the early 1990s. At the time, Apple maintained a downtown Chicago office at 10 South Wacker Drive. My best guess is that the letters were displayed at some time between 1990–2003.
I purchased these on eBay in about 2003. The seller, presumably a former employee at this office, sent an envelope with the letters (pictured) indicating that Apple Enterprise Software was located at this office. At one time, 10 South Wacker Drive also housed Apple’s Chicago Executive Briefing Center. I personally visited the Chicago Executive Briefing Center on several occasions for education-related events, but I do not specifically remember seeing these letters mounted on a wall.
The five letters are made of textured aluminum and are about 4 mm thick. The front of the letters uses a vertically textured “grain” while the backs are flat aluminum. For reference, the “A” is approximately 4 inches tall and 3 inches wide. The back of each letter includes two or three threaded holes. The letters arrived with aluminum threaded posts that had been snipped off (although a few were missing). Each letter is hand-numbered on the back with a marker.
The letters are in Apple Garamond, the Apple corporate font from 1984–2003.