That overpass looks like the one by Tower Records. These are all really obvious places. I'm sure at least half the kids going into the *cough* MIT comp sci building (photo #5) know what it is. Or shopping at Urban Outfitters, or going into a BU dorm.
Oh well, I suppose the downfall is that Ignignot is giving people the finger. That's not going to stay up for very long no matter where you put it.