Christopher Dell lives and works as a theoretician, musician and composer in Berlin. According to the Reclam Jazzlexikon, he is considered the leading vibraphonist in Europe, for which he has been awarded numerous prizes. Dell is the director of ifit, Institute for Improvisation Technology, Berlin. He has taught architectural theory at the University of the Arts, Berlin and the Architectural Association, London, among others, and was a visiting professor of urban theory at HCU Hamburg and TU Munich. At HafenCity University Hamburg, he initiated the research project University of Neighbourhoods (UdN) with others. Christopher Dell's research interests focus on practices and organisational processes of the contemporary city. In interdisciplinary working constellations, he seeks to conceptualise relational forms of action as procedures and to make them fruitful for design. His book »Replaycity« (Berlin 2011) plays with a "musical" understanding that conceives of urban space as everyday co-produced, and from this unfolds a technology of improvisation as urban practice in the 21st century.