Over the past couple years, the government has been modernizing many of the older (over ten years old?) apartment buildings in the city. This has included various things such as new piping, elevators, and windows.
It has also in many cases included the addition of insulating foam to the exterior of the building, topped with some brightly colored paint. (Many of the colors the buildings had previously were drab, and that was even before they begin to fade.)
So, what one ends-up with is something like this: