This report provides the introduction to strategies and design principles for keeping buildings and neighbourhoods in circular use, and a demonstration of how those approaches have been applied to a series of case studies in the CIRCuIT project. With architects and planners as its targeted audience, the report bridges initial risks of demolition, identified to act as barriers to the retention of the buildings, with 12 ‘recipes’ for life cycle extension through refurbishment and transformation of buildings and neighbourhoods in partner cities Copenhagen, Hamburg, Helsinki Region, and London. The demonstration cases are analysed from several perspectives and categorised into a taxonomy, which includes approaches to promote life cycle extension, and factual aspects. Finally, the preliminary findings, both the good experiences and the challenges are reflected upon for each demonstration. Reflections are channelled to recommendations of how cities could further facilitate circular transformation.