Google Street View
In addition to the little Green Church, posted a few days back, I also found this painting of Madonna while roaming the streets of Mexico City.
Google Earth Community Member Hurcoll has informed via this post that there are many such paintings in the city. These are small shrines that are built by the community for one reason or another, sometimes they are placed in the locations where people used to dump their garbage, or gather to drink, or get drugs, etc. and because of these religious paintings or small church like structures they don't throw garbage or carry out nefarious activities in the area. These places are built by the people that live in the area and not by any religious institutions, however the local church priest usually will go to these places and bless these.