A growing global population, changes in lifestyle and behavior, the worsening of the climate change effects put great pressure on natural resources worldwide. On the other hand, levels of waste production and pollution are increasingly alarming. Nations, regions, cities, both urban and rural territories are now in a vulnerable situation that requires new strategies, innovative approaches and tools, but also different mindset and ways of thinking. Territories need methods that support a better and more efficient use of natural resources and minimize the production of waste and pollution. In these complex circumstances, two different but still complementary concepts might help to show the right way, namely urban metabolism and circular economy. The urban metabolism metaphor has been extensively used to describe cities and urban systems as organisms that need resources (as inputs) to support their activities and produce any kind of waste and pollution (negative outputs) as externalities of transformation processes. The urban metabolism metaphor is then useful to analyses material and energy flows that enter, are transformed, pass through and leave urban systems. A more comprehensive understanding of how resource flows and waste interact with territories might help urban planners and decision-makers to developed more proper strategies, plans and policies that foster the transition from “linear metabolism” to “circular metabolism”. This means that resource inputs from external systems (e.g. distant rural or natural areas) are minimized by increasing internal reuse and recycle practices. While the reorganization of spaces, functions and infrastructures are crucial in shaping a new urban metabolism, a change of the economic model is also imperative. This is when the circular economy concept comes in, by promoting an economic system that is regenerative by design. In a circular economy framework, biological material flows can be reintroduced in the biosphere, whereas technical material flows can be enhanced, reused and recycled without harming the environment. Therefore, the circular economy model aims at promoting the reuse and recycle of materials in downstream cycles, minimizing wastage and increasing resource efficiency. The adoption of circular economy principles is an important part in the transition towards “circular urban metabolism”, however this implies the development of new business models, changes in logistics, technological innovation and variations in people behavior. All these changes imply impacts on cities and territories that are unpredictable and for this reason need to be monitored, analyzed and studied. Within the vast urban metabolism and circular economy frameworks, a better understanding of interactions, trade-offs and cause-effect relationships between different resource flows can also lead to more flexible and resilient territories and contribute to build up new synergies between cities, and rural hinterlands. This eventually can favor the development of synergies and circular economy activities that transform the metabolism of cities and territories. The research in this field is extremely interdisciplinary and includes social, technical and ecological aspects equally. Topics of particular interest are: water-energy-food nexus; urban and peri-urban agriculture; waste management and prevention; circular economy in the agri-food sector; circular economy in the building industry; metabolic planning; food planning; regenerative cities; sustainable and circular tourism; foodscape and gastronomic heritage.