More than five years ago - on January 26, 2000 to be exact - Simon Vinkenoog opened the congress 'New Babylon - The value of dreaming the city of tomorrow' held at the Faculty of Architecture in Delft University of Technology. For two days critics, historians and architects discussed Constant's New Babylon and other Utopian projects from the 1960s and '70s. It was a lively congress with the odd nasty academic scuffle here and there. It was also an historic congress because it was one of the few occasions when a number of the authors/designers of the most discussed and influential projects of the 1960s and '70s were present and looked back at their own work, which was again the subject of interest after two decades in oblivion.

Now, at last, we have the book Exit Utopia, Architectural Provocations 1956-1976. No doubt it cost architecture student, congress organiser and editor Martin van Schaik and teacher and co-editor Otakar Mácel a huge effort to turn the congress proceedings into a book. The result, however, is much more than a congress report and has been more than worth the weight. This is an exemplary document of, and an excellent reflection upon, the visionary and sometimes deliberately provocative projects that in their separate ways have celebrated, magnified, criticised or dismissed modern architecture.

Exit Utopia is a collage of texts, projects, interviews and critiques. A major portion of the book is made up of the complete texts and accompanying images of seven projects. The 'paper' architecture projects included were previously published in architecture periodicals. Some, like Koolhaas' Exodus, were published in abridged form in Casabella, while even the standard version in S,M,L,XL is shorter than that in Exit Utopia. After that the projects took on lives of their own as text fragments or as occasional characteristic images. The book is worth buying for the entirely unabridged publication of Paris Spatial (1959-61) by Yona Friedman, Plug-In City (1963-66) by Archigram's Peter Cook and Dennis Crompton, The Continuous Monument (1969) by Superstudio, No-Stop City (1969-72) by Archizoom, The Fundamental Acts (1972-73) by Superstudio, Exodus or The Voluntary Prisoners of Architecture (1972) by Rem Koolhaas and Elia Zenghelis (with Madelon Vriesendorp and Zoe Zenghelis), and of Project for the New Quartier of La Villette (1976) by Leon Krier. The big absentee in this project line-up is New Babylon itself. That turns out to be down to Constant's unwillingness to collaborate. But, as Martin van Schaik states in his epilogue, it was perhaps for the best. For unlike the other projects, New Babylon cannot be captured in a limited number of pages featuring images of words since there is no 'original publication' of the project. What's more, there's a fine monograph available with almost all images and many original texts (New Babylon - The Hyper-Architecture of Desire, by Mark Wigley).

Nonetheless, New Babylon forms the background to and reference point for Exit Utopia. In three extensive chapters Martin van Schaik writes a 'psychogeogram' of New Babylon and fills the gaps left by Wigley's monograph on important points, particularly in relation to biographical and historical details. He puts into perspective the stubborn belief (held in particular by Wigley) that Constant's paintings from the period 1969-1974 - among the best and most penetrating of his career - are 'proof' of Constant's rigorous self-criticism of New Babylon.

The other projects are also subjected to critical analysis in a series of essays that provide historical context. Simon Sadler contrasts New Babylon with Plug-in City. Sander Woertman introduces the Italian Radical Architecture. Francoise Choy discusses Utopia, as does John Heintz, who along with Van Schaik corrects Constant's supposed rejection of New Babylon and criticises Wigley's and Hilde Heynen's reading of New Babylon. Lieven de Cauter and Hilde Heynen contribute an extensive exegesis of Exodus by Koolhaas and Zengelis, and Geert Bekaert deals with the duo Maurice Culot and Leon Krier.

These critical contributions constitute a book in their own right, but they are complemented by a third book: a series of lookbacks by the original designers/authors of the featured projects. Sometimes that takes the form of an interview, such as that with Yona Friedman. And despite Constant's unwillingness to collaborate, the book features the complete English translation of the interview that Betty van Garrel and Rem Koolhaas conducted with Constant in 1966 for the Haagse Post newspaper. Even more interesting are the texts by those involved. Ettore Sottsass, Dennis Crompton, Andrea Branzi, Adolfo Natalini, Elia Zenghelis and Leon Krier look back, sometimes with difficulty (Zenghelis: 'This article has caused me untold pain, loneliness and deprivation), sometimes with amazement, sometimes with new insight (for example, Dennis Crompton's picture comic strip about Archigram's collective working method), but always with complete involvement, on the projects that - though made during a brief period in their careers - have remained vital to their later work and their position in architectural history.

This book is so complete and lavishly illustrated and contains so many fine texts, has been made with such passion and read with such pleasure, that it's almost a crime to make any critical remarks at all. But still, it's a shame there was apparently no space or time to include a good register, even if it isn't customary in such a compilation of essays, interviews and project descriptions. It's also a pity that the original date and place of publication and/or the publication history of the republished projects are not included. A bibliography of each project would have been even better of course, but that would have amounted to a fourth 'book in book'. Perhaps a few other minor remarks could be made, but the editors Martin van Schaik and Otakar Mácel should be absolved in advance. For they've put together a wonderful book!