Maps are the scaffolding of the digital age. Without them, and their associated data, a technological revolution is impossible. Vast swathes of Africa are still not mapped to a true local scale. That means governments face huge problems when tackling rapid urbanisation on this fast changing continent – they simply don’t know where people are. It also means that when outbreaks of disease occur, mapping the spread of infections is all but impossible. Katie Prescott travels to Rwanda, to Kigali, which is rapidly changing its layout and erasing signs of the past, to the border with the Democratic Republic of Congo, where the maps just seem to stop, and to Tanzania’s commercial hub of Dar Es Salaam, to hear how community mapping projects run by students are helping to tackle flooding, and outbreaks of cholera.