"The World Health Organization (WHO) has identified urbanization as one of the key challenges for public health in the 21st century. It is typically discussed in negative terms, including infectious outbreaks, unhealthy lifestyles and environmental threats. Yet cities offer significant opportunities to improve public health through health-enhancing policies and actions. [...] City leaders are key allies in delivering national public health objectives among large parts of the population. City leaders have the means, opportunity and obligation to protect the health and well-being of their people by defining priorities, uniting stakeholders around common goals, and ensuring accountability for outcomes. City leaders’ commitment is important not just for the health of cities, but for global health as a whole. [...] Cities are the main implementation sites for national health policies and programmes – without their support, global targets are unlikely to be achieved. This report is a call for city leaders to rise to the challenge and show the world how local action can help solve global health problems."