These days, the Internet makes it possible to travel much of the world with a simple click of a mouse. But not every place where life gets lived is cartographically represented. This leaves entire communities, particularly slums and other “informal settlements,” invisible from state actors who could implement vital infrastructure like electricity and clean water. Using their feet, GPS technology and a lot of dedication, Primož Kovačič, Isaac Motisiamosa and their teams are collaborating to put Mathare, Kenya’s second largest slum, and its people on the map.