The fifth edition of this series is about the question of how best to deal with the ever-increasing demand for housing – but also the increasing demand for space for the economy and infrastructure – in major German cities. The researchers investigate the question of whether densification and mixed uses can significantly reduce land use. The first results of a pilot study on the development of use in the seven selected German cities of Berlin, Hamburg, Munich, Cologne, Frankfurt am Main, Stuttgart and Düsseldorf show the functional change of highly condensed urban areas. Square-kilometre grid cells show how the relationship between business and housing changed between 2005 and 2015.