Crime and insecurity are deeply entrenched in some cities. While we have rankings of the most dangerous cities in the world, this does not give a clear picture of how and why dangerous spaces develop in cities. We are analysing case studies from cities in France, Colombia, Brazil and Australia to understand the factors that lead to insecurity, and to examine possible solutions. This article written in collaboration with Dr. Gwendal Simon (Universite Est Marne la Vallee, UPEM) is available here