Space is the Machine, a book by Bill Hillier, is available online for free, and is also back in print again after too long an absence. Around 15 or so years ago this book changed how I see the world. As my own well-thumbed paper copy has suffered a lot over the years, and is a very large, heavy object that attracts a lot of dust and not much reading, it is delightful to be able to dip into the pristine electronic version and again be inspired.

This site has each chapter individually downloadable. A full 368-page copy is available at http://discovery.ucl.ac.uk/3881/

The book is as much a work of philosophy as it is of architecture and urban planning (its main subject matter). It incorporates insights from sociology, psychology, anthropology, network theory, linguistics, complexity theory, distributed cognition, systems theory, aesthetics, engineering, ecology, collective intelligence, topology, emergence and more. The ideas it embodies have far broader potential applications than the built environment, including to ways we think about the purpose and practice of education, as well as to more obviously related things like the design of online social applications. In brief, it provides a way of understanding complex human systems and environments as interconnected configurations of structure, objects, time, and movement, in constant dynamic and emergent interplay with abstract, social and psychological phenomena. There are strong echoes of Jane Jacobs (uncited) and Christopher Alexander (cited) in all of this, but it goes farther up and farther in.

I don't know whether the book and the theories of space syntax it describes impress most architects and urban planners. As I am neither, that's not the point for me. Whether all the arguments and conclusions make sense in its intended context or not (and some are a bit suspect, even to an outsider like me) this book repeatedly makes strikingly novel connections between diverse and otherwise incommensurate fields, and it constantly provides new perspectives that make the familiar strange and fascinating. It is inspiring stuff.