Can utopia become reality?
This appears to be the guiding question of Enrico Prandi in his "atlas" entitled "The architecture of the linear city", published by Franco Angeli. A sort of "apology of the line".
The "utopian" text - in the sense of eu-topos, the place of happiness - aims at the apex of the state of the art on applied research to a phenomenal topic, still confined to the realm of utopia, launched since the end of the 800 and perhaps never really ended. Starting from the results achieved by George R. Collins, still considered today the "largest (and almost unique) historical of linear planning", the author assumes as a field of investigation, a vast series of examples that animated an architectural imaginary projected towards new social and urban paradigms. The very rich miscellany of linear city projects presented in the book is described and cataloged according to new interpretative-analytical categories. The methodological approach to the theme, by the author, is rooted in the tradition of studies on architecture and the city, of which "The architecture of the city" by Aldo Rossi is manifest. Linear cities, intended as sets of minimal elements that configure continuous-growth settlements, are investigated by Enrico Prandi in an almost anatomical way, with continuous leaps of scale that allow the real understanding of these complex organisms in constant dialectic between architecture, city and territory.
At the base of these experiments, there was an ethical, moral and practical dream.
Rationalize the use of the territory, welcoming the advent of the prophesied "city of networks", through the experimentation of new urban modular models based on the road as “backbone”. This is the synthesized thought of Soria y Mata, a republican with philosophical skills, the inventor of the linear city typology inhabited by "linear citizens". According to Prandi, linear cities represent the last bastion of sustainable urban planning, because it is still based on the anthropocentric concept of "ideal city", which pursues an order that is even more mental than spatial.
The index, accompanied by a synoptic table very useful for the reader to frame the theoretical palimpsest of the book, transforms the above-mentioned interpretative categories identified by the author into chapters.
The structure of the publication can be metaphorically understood as a space-time journey between the evolutionary thresholds of the urban model in question. We start from the origins triggered by a vision confined between utopia and ideal cities, and we arrive at the demonstration of the almost physiological advent of the contemporary "natural linear cities", real polycentric territorial systems innervated by the infrastructure (Città Emilia, Roadtown ER, FO-CE, Adriati-città, NOMARE, Hyper Adriatica, Future GRA). Extreme ratio, are two contemporary examples of linear city projects, demonstrating the fact that research on the theme of linearism has never really ended: the North-West Director of Milan, by Guido Canella (1993) and VE_MA of Franco Purini (2006).
The Ciudad Lineal by Arturo Soria y Mata (1882) and the Cytè Linéaire Belge by Gonzalez del Castillo (1919) referable to the Kandinsky triptych “dot, line, surface”,  represent the prototypes of the linear city, developed then in the world in the coming years . The two geo-political rivals America and the  Soviet Union had considerable importance. The first, territory of large abandoned spaces, protagonists of Blake's "God's own junkyard", is the canvas of Wright's organic formations (Broadacre City), of the sociological findings of Richard Neutra, translated into his "running city" (Rush City) ) and of the first experiments of Ville Radieuse by Le Corbusier of 1933 with its "three human settlements" in the systemic logic of a "great urban assembly line". From the linear city we passed to the experiments of the "linear metropolis" of Reginald Malcomson. Hence, the project by Michael Graves and Peter Eisenmann of the Jersey Corridor which anticipates the concept of "Bigness, or the problem of large size" (R. Koolhaas) and which sets out the principle of "cluster point". The  Soviet Union, always anti-capitalist, puts man at the center of linearist experimentations. Le Corbusier himself was a great supporter of the USSR  as fertile context for an urban revolution. The models of socialist linear cities, from the projects for Miljutin and Leonidov's Magnitogorsk, to the Green City of Ginzburg and Barsc, are the emblem of a community vision of urban settlement on a human scale, in part analogous to the principles of the “city humanized " by Lluis Sert.
Europe also played a fundamental role in the development of the linear urban model; the region became the application area of linear cities in constant tension between small and large scale as expressed by Ludwig Hilberseimer. His vertical city, whose atmosphere that transpires from the drawings is worthy of a scene of Inception so that the same author compares it to a necropolis, goes in the sense of regionalization. A key passage in the book is the analysis of linearity in the expansion plans of the built city, starting from Plan Obus with the concept of "fifth façade" and of Plan Voison, both of Le Corbusier. The Great London Plan, signed by the collective MARS (Modern Architectural Research Group), promoters of modern architecture through the dissemination of matter, assumes the typical linearity of the socialist approach as a directrix of the urban expansion of the city of London set on " contact theory ". This vision, abandoned because it was considered too radical, was initially supported by the Architectural Review magazine.
The realm of utopia comes to interface with the built city.
The analysis of the historical episodes of interaction of the linear city project with the constructed matter of the consolidated city, is a fundamental step of the book towards the answer to the initial guide question. The twentieth century is assumed by the author as a season of great urban transformations. The practice of building substitution and the reconstruction of significant parts of the city starts. Linearity is forcefully imposed as a refounding matrix through the insertion of real prostheses in the existing, and no longer just conjunctions between full and full. Derived articulated patterns composed of interconnected architectural elements according to lines of force, within urban fabrics. Examples of this remodeling of the built are the project for Market Street East by L. Kahn and Unter Der Linden by Van Eesteren for Berlin. In both cases, the design choices are dictated by the predominant advent of the machine as the main means of transport. The parking lot was therefore seen as a potential destructive element of the urban order. Kahn, for Philadelphia, inflicts the theme of parking to pursue the exact opposite with his linear regenerative strategy. The Philadelphia reimagined by Kahn is, therefore, a city able to defend itself from the car, in analogy with the medieval fortified cities for reasons of a completely different kind, through intermodal exchange points called "docks".
The author, in the practice of inserting linear devices (prosthetics) in the existing building, analyzes in parallel to the professional experiments, the academic ones. The Urban Renewal, a movement born from laboratory realities within the four American university landmarks (Princeton University, Cornell University, Columbia University, Massachusetts Institute of Technology), immediately confronted the issue of Harlem-Manhattan regeneration. The area was divided into four project areas with a wide linear extension and each of them was entrusted to one of the university working groups. The outcomes led by group leaders, including Peter Eisenmann, Michael Graves and Colin Row, are evidently mindful of the linear city models of Chambless (Road Town) and Le Corbusier (Algiers and Rio).
Another example of a linear prosthesis inside the building was the LOMEX (LOwer Manhattan EXpress) by Paul Rudolph. This is a linear city that transports all the infrastructure of the peninsula of Manhattan to the hypogeum level, bringing out from the country floor, highly monumental pyramid elements, assembled in order to create an urban corridor and containing the various typical functions of its own functional mixité of the great experimental "vectors" of the period. The idea behind LOMEX flows into that utopian territory, defined by the author "Manhattismo", then denounced by "Delirius New York" by R. Koolhaas.
The linear city then became the type adopted in the experiments of the so-called "Ecocittà".
Projects born as an alternative to the chaos of contemporary cities from which some of the designers themselves escaped. Paolo Soleri above all, found refuge in the context of his training as an architect, the Arizona desert. Right here, in Arcosanti, a self-built city of foundation with the help of a changing community set up specifically on site, he carried forward the ideas of his Mesa City and Lean Linear Arcology.
Less radical in the choices of life but not in the ideas of the city, were Marcello D'Olivo with his Eco-Town and Luigi Pellegrin with its "habitats" made up of vectors composed of neo-lines and neo-mounds.
According to the writer, the maximum level of utopia dealt with in the book is that of "megastructures". 1964 was the "mega-year" of megastructures' maximum production of megastructures (E. Prandi). Kenzo Tange, Alan Boutwell and Mike Mitchell, Yona Friedman, Superstudio, Archigram, Archizoom, OMA; all struggling with the collage technique to create new fantastic cities suspended and superimposed on the old, almost denying them.
A dense book, straddling historiography, architectural and urban composition, which answers the initial question, despite the demonstration of the advent of contemporary natural linear cities, thus: "Perhaps the most interesting aspect (of linearist experience) is constituted by the "not feasible", that is from those visionary prefigurations that, anticipating the future, stimulate the cultural debate. The value of these proposals resides on the scientific-figurative level rather than on the technical-practical one. [What Giorgio Grassi writes about the Tange Plan for Tokyo can generally be applied to multiple proliferated solutions (...). The study of Tange has value (...) as research, where the concrete result is necessarily partial, where the synthesis is valid as a deepening of the topics contained (...); if it is usable or not I do not think it has (...) importance.] (G. Grassi, 1961)”. 

[1] Title extracted from the beginning of the Peter Assmann lecture, in occasion of the "Paradisi immaginari" hexibition in the Polytechnic of Milan, headquarter of Mantua. Assmann introduced the lecture by an extract of Sharlock Holmes adventures: “Nothing, my dear Watson, is so fantastic as reality!”.

Paolo Strina