The Old Colony Building, a landmark building, in the Loop, was getting a facial of sorts earlier this week. (According to an on-line article, here, The Old Colony Building was one of the first buildings constructed after the Chicago Fire. Its architects, Holabird & Roche used the "Chicago Style" design steel frame structure that enabled skyscrapers to be built.)
This work crew was power-washing the building facade. I didn't see the the scaffolding at first; what caught my eye were the parked cars covered in plastic. That made me look up to see what was going on. I think you can better see the progress they've made in the second picture.