This lecture covers the concepts of urban metabolism and circular economy, focusing on material and energy flow analysis for resource management in cities. It discusses the system definition of cities, accounting approaches, and examples of urban MFAs. The lecture explores the relevance of urban metabolism, system boundary definition, and different accounting approaches such as top-down and bottom-up. It also delves into the comparison of territorial/production-based vs. consumption-based accounting, policy measures at the urban scale, and the implementation of circular economy policies in cities like Brussels, Paris, and London.