Re-use, up-cycling, circular economy – are these just buzzwords, or do they offer sustainable concepts for urban planning? This question is currently being asked by architects, urban planners and city initiatives. As a counter-model to the linear industrialised economy based on planned obsolescence, these new approaches seek to make use of raw and used materials, which can be re-introduced into new production cycles. This principle can also be applied to urban and architectural spaces: vacant sports halls, desecrated churches, abandoned cemeteries, and post-industrial sites. What modern techniques and strategies are available?