In 1965, the architect and design theorist Christopher Alexander published a landmark theoretical critique of modern urban design, and by extension, modern design in general. His critique was different from others of the day in that it was not based on a social or political argument, but rather, on a structural analysis, rooted in then-emerging insights from the fields of mathematics and cognition. Here, published again on its fiftieth anniversary, is Alexander's classic text, together with new interpretive commentaries and discussions by leading theorists and practitioners. This volume is destined to become an invaluable resource for a new generation of students and practitioners. "One of the classic references in the literature of the built environment and associated fields." - Resource for Urban Design Information (rudi.net) "At a time of increasing concern over the adequacy of design methods, "A City is not a Tree" broke open and reoriented the debate." - Charles Jencks and Karl Kropf "It pointed clearly to a change in the way we need to think about cities." - Bill Hillier, Chairman of the Bartlett School of Graduate Studies, University College London "Remains a landmark in our thinking about cities and design...It is a new beginning -- for Alexander and for urbanism -- to discover what the city really is." - Luis Bettencourt, Santa Fe Institute Christopher Alexander  (principal author) is one of the seminal figures of 20th Century design theory, and an author of highly influential works including Notes on the Synthesis of Form, A Pattern Language, The Timeless Way of Building, A New Theory of Urban Design,  and The Nature of Order . He has also designed and built many structures as a practicing architect and contractor. CONTRIBUTING AUTHORS:  Michael Batty is Bartlett Professor of Planning at University College London where he is Chair of the Centre for Advanced Spatial Analysis (CASA).  Luís M.A. Bettencourt is Professor of Complex Systems at the Santa Fe Institute.  Howard Davis is Professor of Architecture at the University of Oregon and co-director of the Collaborative for Inclusive Urbanism.   Jaap Dawson is a practicing architect, and recently retired from teaching at Delft University of Technology.  Bin Jiang is Professor in GeoInformatics and Computational Geography at University of Gävle.  Michael Mehaffy  (editor and co-author) is Executive Director of the Sustasis Foundation and editor for Sustasis Press, and a researcher, educator, and practitioner in urban design and strategic urban development, with an international practice based in Portland, Oregon.   Hans Joachim Neis is a Professor of Architecture and Director of the Architecture Program at the University of Oregon in Portland.  Dellé Odeleye is is Course Leader of the MSc Urban Design at Anglia Ruskin University.  Sergio Porta is Professor of Urban Design and former Head of School at the Department of Architecture, University of Strathclyde, and head of the Urban Design Studies Unit.  Yodan Rofé is a Senior Lecturer of Urban Planning and Design at Ben-Gurion University, and founder and former Board Member of the Movement for Israeli Urbanism (MIU).  MariaPia Vidoli  is a researcher at the Urban Design Studies Unit (UDSU) of the University of Strathclyde in Glasgow.