Book excerpt: With cities striving to meet sustainable development goals, circular urban systems are gaining momentum, especially in Europe. This research-based book defines the circular city and circular development. It explains the shift in focus from a purely economic concept, which promotes circular business models in cities, to one that explores a new approach to urban development. This approach offers huge opportunities and addresses important sustainability issues: resource consumption and waste; climate change; the health of urban populations; social inequalities and the creation of sustainable urban economies. It examines the different approaches to circular development, drawing on research conducted in four European cities: Amsterdam, London, Paris and Stockholm. It explores different development pathways and levers for a circular urban transformation. It highlights the benefits of adopting a circular approach to development in cities, but acknowledges that these benefits are not shared equally across society. Finally, it focuses on the challenges to implementing circular development faced by urban actors. This ground-breaking book will be essential reading to scholars, students, practitioners and policymakers interested in the circular economy, urban sustainability, urban ecology, urban planning, urban regeneration, urban resilience, adaptive cities and regenerative cities.