While developing a master plan for Medellin's urban lighting system, EPM, Medellin's public utility company, analyzed the Colombian city's infrastructure and nocturnal lighting system by superimposing a map of the system over a map of the city. What they found was an urban landscape blotted by "islands" of darkness.
Much to the surprise of the utilities company, the dark spots were actually 144 water tanks that were initially built on the city's outskirts; however, thanks to the progressive expansion of Medellin's city limits, the tanks now found themselves completely surrounded by the informal settlements of the Aburra Valley. Even worse, they had become focal points for violence and insecurity in neighborhoods devoid of public spaces and basic infrastructure.
