Yes, August wallpaper (as pointed out by several of you) was running late. In honor of that, it's also rusty and beat all to hell.
This was taken here in Raleigh actually back at Pilot Mill. It's a detail from a found art display in their parking lot. I haven't gotten anything better than a guess: Reclaimed from a building-wide pneumatic system. You know for delivering messages like at a drive-up teller window. Or, say Brazil.
Get a tetanus shot and the MacBook friendly size above. A cinema display sized one is available as is an old school 4:3 aspect ratio as well.