Anonymous artist group, Luzinterruptus, has been highlighting problems in their city of Madrid using outdoor lighting installations called "interventions" since 2008. In their own words:

"We began to act on the streets of Madrid at the end of 2008 with had the simple idea of focusing people's attention by using light on problems that we found in the city and that seem to go unnoticed to the authorities and citizens...Sometimes we simply want to embellish, or to highlight anonymous places or corners that seem special or objects to which we think extraordinary artistic value, although they have been left on the streets for unknown seasons, with artistic intention, by anonymous people." 

[Thisiscolossal]