In 2015 the city of Medellín, in Colombia, was still recovering from decades of extreme violence and had one of the highest inequality rates in Latin America. Ten years later, it is regularly cited as one of the world's most innovative urban regeneration stories. The change did not happen by accident. The city built libraries in the poorest neighbourhoods, opened public escalators up steep hillsides so that residents could reach the metro, and reorganised the whole bus network to serve the outer districts first. Air pollution fell. Homicide rates fell. Tourism doubled. Not everything is fixed — accommodation in the central districts has become unaffordable for many locals, and homelessness has risen slightly. But the mayor at the time argued that the goal was never a perfect city; it was a city that could keep improving.
