Tag Archives: Marco Maretto



U+D  issue 15   EDITORIAL

by Giuseppe Strappa

In the life of every journal, I suppose, there are moments of reflection and regeneration: one takes a look at the work done and takes stock, looking at the future with new eyes, and makes plans. The U+D new issue is one of these moments for us. It is the result of a considerable commitment by the entire editorial staff, and we present it, I must admit, with some expectations. It poses, in fact, two relevant goals.

The first is to try to review the current situation of research in Italy concerning urban morphology, particularly in architecture schools. Courses in this discipline are now active in the faculties of many countries, which share the need for rationality, concreteness, transmissibility of the proposed methods. In Italy, the signs seem contradictory. In Rome, for example, despite the presence of an important tradition that stems from the teaching of Saverio Muratori, the urban morphology course has become optional. In other faculties such as in Bari, Bologna, Ferrara, Florence, Milan, Naples, Palermo, Parma, Turin, Venice, these courses, even if given with a limited number of credits, are highly active and open to new perspectives. The term “urban morphology” is employed in an extended and open meaning, as a study of the form of the built landscape based on different founding principles, which share, however, their role as a rational and communicable tool aimed at the project. For this reason, I believe that urban morphology could also prefigure a choice of fields (sometimes not easy) with respect to current production, often based on methods aimed more at communication and individual expression than at construction. Against this egocentric inclination of the architect, in the past schools have in some way constituted a remedy, playing an important aggregation and sharing role. Yet, I wonder if it is still possible today to speak, in the proper sense, of schools. They presuppose masters and require, together with common theories and methods, shared values. The master is such not only for the quality of his scientific production, but above all for his ability to express common goals, the competence to recognize a common substratum in the work of individuals. Just as the school is an organism, a unit of parts held together by a unifying objective. Two conditions that are impossible today: we have long lost the unity of things, the vision, or at least the hope, of an organic world where every knowledge finds its place, every cultural heritage its congruent location.

Nonetheless, there is no doubt that specificities and shared lines still exist, albeit indirectly. I believe that the contributions of this issue, at least in part, are proof of this. Moreover, the study of urban form, in order for it to be a field in which differences have a rational and legible basis, is the terrain that best allows us to distinguish areas of research and affinities, and also oppositions, which originate even further back than the lesson of the masters. The specificities of the Milanese research have more distant roots than the writings of Aldo Rossi and Guido Canella, they have their distant origins in the Lombard Enlightenment; the experiments in the Roman area go beyond the lesson of Gianfranco Caniggia and Saverio Muratori, they go back to the studies of Gustavo Giovannoni, Giovan Battista Milani and many others. But these specificities are now unstable, recognized in an uncertain and controversial way. It is no coincidence that today there is no disciple who is willing to defend that legacy openly, who does not feel obliged to claim his secularism, his independence. It is true that identity, in the contemporary condition, is not inherited: it is a strenuous search in which the vigorous defense of the origins can be a risky bond. The contemporary condition of those who investigate the urban form is that of a disorientation: orphans of the masters, whose lessons we jealously guard, we understand how certainties no longer exist, how it is impossible to reconstruct the lost unity of things.

Yet, perhaps there is, more than we are willing to admit, a long-lasting cultural layer that gives a sense of continuity to our research. I believe that, to understand how the Italian response to the new demands of objectivity and realism shows its own characters, it is necessary to compare it to the “quantitative” drift of the studies often conducted abroad, influenced by the success, even professional, of the Space Syntax. Certainly, useful studies which throw new light on the structures that regulate the shape of cities, but still giving an indirect contribution to the urban project. On the other hand, I believe that many of these studies, based on the notions of density, flows, networks, are in my opinion an update of the issues addressed by the traditional urban planning discipline. This diversity perhaps explains, if it does not justify, the improper term, used above all abroad, of the “Italian School”, because it is true that the research on the form of the city is characterized with us by a humanistic and historical background that has always prevented determinisms and taxonomies, allowing us to recognize how a building or a fabric exists, in its fullness, only in a more general context, in a becoming that, together, explains them and gives them meaning. Although the invitations to the participants to the study day did not cover the broad spectrum of research that derives from the multiple meanings of the term “urban morphology”, I consider the almost total absence, in the following contributions, of the strictly “quantitative” field of study to be significant. A remarkable specificity which allows us to look with optimism at the original role that studies conducted in our country can play on the international scene. In my opinion, the evidence of this condition poses with increasing evidence, after the long late-romantic season of individualisms and spectacular gestures, the problem of a radical renewal of research in architecture that could give our work a new civil sense.  Beyond the slogans, the real tools of sustainability and regeneration of our cities (which will not die of Covid, with all due respect to our prophets of the return to the villages) consist, I am convinced, precisely in the careful study of the built reality and its form, its continuity and its ruptures, which provides awareness of the crisis we are going through and can show us the way to future transformations.

The second important goal of this issue is to experiment new forms of construction and a different way of collaborating with the authors, having in mind the place of our journal in the international panorama of studies that are being conducted today on urban form. Perhaps it is useful, in order to understand the urgency of this issue, to summarize the cultural framework in which our work arises.

The magazine was born in 2014 as an Italian contribution to the International Seminar on Urban Form (Isuf), a scientific society that already owned its own, relevant journal dedicated to urban morphology. However, it was interested in it, above all from the point of view of geography, in the wake of the research of M.R.G.Conzen. His fertile teachings, heirs of the Kulturlandschaft, were developed in the 70s by the Urban Morphology Research Group (UMRG), with which we found, at the beginning of the 90s, considerable affinities and promising prospects for collaboration, starting from the very definition of “urban structure” realistically understood, basically in architectural terms, as an integrated system of routes, lots and buildings. But also, some significant differences. Geography is above all a descriptive science, when the goal of urban morphology, from our point of view as architects, is above all aimed at the project. The problem of geography is to make the infinite irregularity of a mountain ridge coincide with the simplicity of the line drawn on a map. It is the difficulty of any descriptive science that seeks synthesis in the general and abstract representation of the concrete details of the object it describes. The problem of architecture is different: recognizing in that ridge a beginning, a first provisionally inhabited form and the origin of the paths that structure a territory. Saverio Muratori had devoted a lot of energy to formulating a “theory of ridges” based on the shape of the soil and its anthropization process. A formulation conducted with the designer’s tools. Was it, too, a science? Certainly yes, if by the term we mean a form of systematic knowledge. But it was also a critical form of investigation, a reading oriented by the operating subject that proceeds by layers and phases, recognizes in the object the aptitude for transformation and, fundamental fact, the expression of a civil context. Reading is therefore already a project, it is an evaluation and a choice. For this reason, it cannot aspire to the (moreover relative) objectivity of the descriptive sciences, as well as the design that follows is the full responsibility of the designer, with the inevitable discontinuities due to an evident condition of crisis.

However, the Conzenian school had inherited a particular meaning of geography, that of the cultural landscape, of the territory as a synthesis in the making of successive transformations. A meaning that we felt close to. This is the definition of urban morphology that Jeremy Whitehand, the best-known exponent of the Conzenian school gives: ‘Urban morphology is the study of the built form of cities, and it seeks to explain the layout and spatial composition of urban structures and open spaces, their material character and symbolic meaning, in light of the forces that have created, expanded, diversified, and transformed them ‘. A broad and open meaning, in many ways similar to ours. On the wave of this affinity, Isuf was born, which over time had to reach its current dimensions of international association, transforming itself into a large container in which many souls live together. The Italian journal, therefore, was born as a complementary communication tool devoted to the reading and to the architectural design. Within this context, our initial aspiration was to consider the journal itself as a project, an architecture in some way, made up of congruent parts linked by a relationship of necessity. The ideal reference could only be the post-war publishing tradition, the season in which architecture magazines reported the great debates that then revolved around the revision of the international modernity. We soon realized, however, how that production was the result of a cultural climate in which different and cohesive communities of experimenters converged, who grouped around common convictions, making clear the positions taken, clear debates and controversies. A quite different climate from the current one, fragmented in many separate research, rarely communicating with each other. Moreover, within a more general condition in which the common meaning of the term “form” considers the rational and concrete aspect of our profession to be of little relevance. A context in which the term “type” smacks of archaeology and those of “construction” and “fabric” of obsolete techniques, despite the fact that their unifying meaning, and their civil value are in direct relationship with the emerging issues of the current city.

Every author ends up today by producing autonomous contributions to the journals, linked to the others only by a common theme. For this reason, we have tried to involve some designers and scholars interested in the problem of the concrete study of urban form already in the planning of this and the next issue. At the same time being aware, however, of the inevitable partiality of the operation. While we were not deluding ourselves that the structure of the issue could be born from this day of study (task and responsibility of the editorial staff), we believed that this meeting could however compare themes, ideas, points of view in such a way that each author could take into account the context in which his article ranks. It seems to me that the result confirms, with all the limits of an experiment, the effectiveness of the method. This issue, in fact, does not constitute a form of proceedings of the study day, but the collection of contributions by it oriented, often quite different from those presented during the meeting.

The articles derived from the study day are partly published in this and partly will be published in the next issue of the journal. The following issue, just because of the questions that have arisen on the concrete usefulness of morphology studies, will be dedicated to the urban project.



by FRANCO PURINI – in Paesaggio Urbano n.1, 2014

Team leader: Giuseppe Strappa
Project team:  Alessandro 
Camiz, Paolo Carlotti, Giancarlo Galassi, Martina Longo. 


click here              Purini su Carezzano  

An extensive debate about the city, based on different
and sometimes radically divergent models, in recent
years attempted to verify, using interpretative models
developed by the twentieth century architectural culture,
what was going on in cities.
Among these, three models can be distinguished because
of their complexity, clarity and interest.
With regard to Italy, the first of these models follows a
study tradition dating back to Gustavo Giovannoni,
Saverio Muratori, Gianfranco Caniggia, Giancarlo Cataldi
and Pier Luigi Maffei. This one is the most influential
and enduring theoretical and operational model on urban
studies produced in Italy, and it considers the city as
an organism with a layered structure.
The second model interprets the city as a system of
dynamic relationships, as a communicative flow
of networks. The city is considered here more than a
physical fact, a pure projection of information and events,
a chaotic and metamorphic simulacrum, a collage
suspended between the city of Colin Rowe and Fred Koetter
and the generic city of Rem Koolhaas. What appears to be
essential to this point of view is the immateriality of the city.
The landscape is the keyword to the third model. Assuming
the landscape paradigm, the city lost not only its physical
identity but also the immaterial one: a neo-naturalistic vision,
blurring the microcosm into the macrocosm, took the place
of identity.
Giuseppe Strappa is one of the most prominent members of
the structuralist line, attentive and creative interpreter of the
Caniggian lesson (continued with remarkable originality);
he has succeeded in creating an actual School, based on
the notion of architectural and urban organism, within
the Faculty of Architecture in Rome. His conception
of architecture is based on the relationship between
unity and parts, plasticity and elasticity, uniqueness
and seriality, design and construction, and between
many other dialectical dyads. The project proceeds
not only in an analytical way, but also following
indirect and unpredictable paths where memory and
emotion make the invisible visible. His theoretical and
architectural work is anyway open to a constant critical
review, comparing his beliefs with what emerged from
disciplinary alternatives.
One of the last works of Giuseppe Strappa, the
redevelopment of an area of the historical center
of Carezzano Maggiore in Piemonte, is a kind of
exemplar manifesto where the coincidence between
an admirable theoretical accuracy and a recognizable
architectural writing maturity produced a more
than significant result. This project, first prize winner of a
competition, was elaborated by a design group directed
by Giuseppe Strappa, with Alessandro Camiz, Paolo
Carlotti, Giancarlo Galassi, Martina Longo, and by the
collaborators Marco Maretto, Nicolò Boggio, Pina Ciotoli.
It is the outcome of three intentions: the accurate
reconstruction of the formation phases of Carezzano
Maggiore, the contribution of that part to a new identity, the
definition of a spatial warping which, through a careful and
inspired decodification of the metrics of the urban tissues,
reorganizes the existing settlement enrolling it into a
new set of urban relationships.
The buildings were recasted into a new facility enclosing a
new civic center, following the palazzo type evolution. For the
variety of content and the way in which it is composed into a
coherent system, the project gives a convincing answer to
the new paradigm of urban regeneration.
The project of Giuseppe Strappa is the result of listening
to the formation phases of the city and to the urban
imagination. An imagination which, by incorporating the
built memory, resulted in a complete and definitive form,
always rational, but, in its very nature, unspeakable. There a
also emerges from the project a sense of duration and at the
same time the representation of how, conversely, the
circumstances that produced it must be transcended to be
seen as something suprahistorical.
Finally, this work shows how the structuralist line on the
interpretation of the city is able to promote innovative
responses to more complex urban problems. It points out
that the city can not help but design ideas that move from
its collective identity.

Attualita’ della proposta di M.R.G. Conzen

Attualita’ della proposta di M.R.G. Conzen

Giancarlo Cataldi, Gian Luigi Maffei,  Marco Maretto, Nicola Marzot, Giuseppe Strappa

Presentazione del libro L’analisi della forma urbana (Franco Angeli, Milano, 2012) edizione italiana del libro di M.R.G. Conzen, Alnwick, Nurthumberland. A study in Town Plan Analysis Institute of British Geographers, London 1960
















L’edizione italiana dello studio su Alnwyck riveste, a nostro avviso, un significato che va oltre la documentazione dell’analisi esemplare di una piccola città inglese ai confini con la Scozia, per acquistare un senso più generale.

Con la fondazione dell’Isuf (International Seminar on Urban Form), nel 1994, gli studiosi italiani di morfologia urbana hanno scoperto il patrimonio di conoscenze della scuola geografica inglese che fa capo a M.R.G. Conzen, illustre geografo di origine tedesca autore dello studio che qui presentiamo, e dei suoi continuatori, J.W.R.Whitehand, T.R. Slater, P. Larkham, K.Kropf, oltre al figlio Michael Conzen.

Non solo ne veniva riconosciuta l’affinità con molte delle proposte sviluppate dalla scuola italiana, sulla scia dell’insegnamento di Saverio Muratori, ma, soprattutto, se ne costatava la reciproca complementarità ponendo finalmente le basi concrete, dopo tanto parlare di rapporti interdisciplinari, di un lavoro comune attraverso il quale geografi e architetti potessero condividere, all’interno di uno stesso terreno di studi, metodi di ricerca e, ci si consenta il termine, “vocazioni” comuni. Perché, questo è il punto, il lavoro di M.R.G. Conzen dimostra una spiccata propensione a interpretare la città e il territorio come sintesi vitale di un flusso di esperienze storicamente individuate. M.R.G. Conzen ha compreso in modo operante, in altre parole, quello che per noi costituisce la sostanza stessa dell’architettura: che ogni forma (del territorio, della città, degli edifici) è il risultato di un processo, della progressiva associazione organica di parti, e che ha senso scomporla e indagarne le componenti solo se si tiene conto della sua sostanziale unità e indivisibilità. Possedeva, dunque, una nozione di organismo urbano e territoriale che, mai espressa attraverso esplicite definizioni, ha operato come un sostrato profondo nel dare coerenza “architettonica” alla struttura teorica della propria indagine.

Questo dato costituisce uno dei grandi motivi d’interesse dello studio su Alnwick, ma anche, riteniamo, la ragione dell’attualità della proposta di M.R.G. Conzen: lo sforzo di comprendere la forma delle cose non per quello che sono, ma nel loro divenire storico permette, infatti, di leggere anche le condizioni di lacerazione della forma del territorio contemporaneo come stato di transizione, momento provvisorio di una trasformazione continua il cui carattere è, in questo, non troppo diverso da quello città medievale in perenne cambiamento, ed è informe solo per chi non sappia leggerne la latente aspirazione alla composizione e all’unità. E’ proprio questa aspirazione a riunire il molteplice, più che l’unità in se, a dare forma alle cose e senso al progetto.

In questo senso la lettura di Alnwick è l’individuazione di una teoria: la storia perfetta di un piccolo borgo narrata nelle sue fasi formative fino alla condizione contemporanea. Fasi ricondotte a provvisorie unità da un singolare “epos geografico” che individua, rende cioè unici e irripetibili, comportamenti generali che la lettura riconosce come patrimonio comune di molti altri insediamenti e territori dove la forma del suolo e il lavoro dell’uomo stabiliscono una solidarietà riconoscibile come “tipica”.

E’ di natura architettonica, inoltre, una delle principali innovazioni nella lettura del territorio introdotte da M.R.G. Conzen, quella di fringe belt, che ha a che fare direttamente non solo con la documentazione che il cartografo riporta attraverso convenzioni, ma con la lettura critica, che coincide con il progetto delle trasformazioni.











Si tratta di una nozione complessa, cui è impossibile associare un termine italiano, tant’è che nella traduzione abbiamo dovuto impiegare una perifrasi ma capace di fertili traslazioni dall’ambito strettamente geografico a quello progettuale, contribuendo a cogliere, oggi, alcuni caratteri fondanti dell’instabile metropoli contemporanea. In realtà le idee affini di “perimetro” e “confine” sono state da qualche tempo alla base della lettura di qualsiasi forma del costruito, in particolare nel campo degli studi urbani condotti da architetti, mettendo in luce, tra l’altro, la storica contrapposizione tra città e campagna e il suo disgregarsi nel magma dello Spratly urbano. Eppure esse sono capaci di cogliere solo uno degli infiniti stati di transizione, semplificando le letture ma anche riducendone il significato. Propongono, in altre parole, uno sviluppo discreto di un processo in realtà continuo e che procede, nondimeno, per fasi di accelerato sviluppo seguite da altre di rilevante stasi. La nozione di fringe belt coglie invece le trasformazioni intermittenti del perimetro nel loro fluire: non solo come confine, ma come premessa di una nuova struttura dapprima fluttuante e incerta (liquida, si direbbe oggi) che si consolida, viene demarcata e diventa più stabile nel tempo. Compresa a fondo, l’innovazione terminologica e metodologica conzeniana permette di interpretare la frammentazione delle periferie urbane non semplicemente come caotiche, e per questo indecifrabili, lacerazioni, ma nel loro significato autentico di strutture in formazione, delle quali vanno riconosciuti caratteri evidenti e potenziali.

Questa innovazione, rivolta alla realtà dei fenomeni in atto, sembra oggi tanto più attuale, quanto più le analisi urbane si vanno distaccando dallo sviluppo dei fenomeni concreti.

E’ in questo senso che l’edizione italiana dello studio su Alnwick ha il significato, come si diceva, di una proposta alternativa: individua un fronte comune contro la deriva astraente di molte delle riflessioni contemporanee sull’architettura alle diverse scale del territorio, della città, degli edifici. Ci confrontiamo oggi, infatti, con una crisi dai caratteri ignoti nelle grandi fasi di transizione del passato, dove la lettura indiretta e mediatica del mondo costruito va sostituendo la conoscenza diretta della realtà, svincolando la forma progettata dalle relazioni organiche che dovrebbero tenerla unita agli altri aspetti dell’uso del territorio. Smarrendo, in fondo, le basi che permettono di leggerne la reale complessità e di cogliere l’istanza a quel vicendevole rapporto di necessità tra le parti che il grande flusso delle modificazioni del paesaggio costruito, forse più che nel passato, oggi ci pone.  Senza la nozione di organismo urbano, senza la forma data da un confine pur mutevole e strutturante, la lettura di una condizione in rapida trasformazione, gli spazi dei margini irrisolti della città contemporanea acquistano il significato, suggestivo quanto inutilizzabile, di grandi schegge in conflitto tra loro. Lo spazio delle nostre periferie finisce così col ricadere nel grande mare del pittoresco metropolitano, dei territori “ibridi e vaghi”: la città reale come combinazione fortuita, uno dei tanti casi del possibile.










Si vedano, per convincersene, le interpretazioni della città contemporanea (da Virilio a Koolhaas) che hanno conquistato intere generazioni di architetti, dove la metropoli diviene un luogo della mente che racchiude personali rappresentazioni delle trasformazioni in corso, livelli sovrapposti di “architetture eventuali”, layers di realtà possibili e discontinue, secondo una cultura disciplinare che organizza, di fatto, il consenso alla crescita della metropoli contemporanea per addizioni ininterrotte e seriali.  E’ evidente, se solo si alza lo sguardo al di sopra delle contingenze, come la funzione dell’architettura sia ancora quella dell’arte borghese, ancora quella tafuriana di “allontanare l’angoscia introiettandone le cause” che racchiude, anche, l’ambizione di progettare la casualità del molteplice letto nei suoi frammenti separati: l’evocazione della complessità contro la sua soluzione. Scomparsa la pertinenza con la propria fase storica e con la propria area culturale (tolte dal loro tumultuoso contesto economico e antropico) le forme si trasformano in oggetti di evocazione. Una tecnica di seduzione, dove le contraddizioni sembrano di volta in volta, illusoriamente e paradossalmente, sciogliersi nell’eccesso dello spettacolo.

Non è, dunque, un caso che lo studio su Alnwick, e la proposta di metodo che contiene, siano proposti al lettore italiano proprio oggi, quando la produzione neoromantica dello star system internazionale pone quesiti sul ruolo stesso dell’architetto, sulla sua funzione anestetizzante di mediazione culturale e politica.

Comprendere il testo di M.R.G. Conzen significa scoprire (o confermare) una via d’uscita: leggere il territorio e la città contemporanei non come semplice, apparentemente neutrale constatazione di come essi ci appaiono, ma come processo operante e conflittuale, che permette di interpretare, scegliere, disegnare in continuità col grande flusso di trasformazione del costruito e della sua storia.










FrancoAngeli, Milan 2018

edited by Giuseppe Strappa


The form of expanding cities  – Giuseppe Strappa
Metropolis in transformation .

A study of fringe belts in Belo Horizonte, Brazil:
a contribution to developments in urban morphology
Staël de Alvarenga Pereira Costa, Karina Machado
de Castro Simão »

The contemporary metropolis growing.
The case-study of Buenos Aires
Anna Rita Donatella Amato »

Urban densification, vertical growth and fringe
in American cities
Paolo Carlotti »

Guangzhou-Foshan Metropolitan Area.
An adaptive notion of urban fringe belt for the
continuing Chinese city
Anna Irene Del Monaco

The growth of traditional cities

Post-industrial Eindhoven and its radial fringe belt:
A morphology of contemporary urban growth
Daan Lammers, Ana Pereira Roders, Pieter van Wesemael »

Conquest of organicity within the Liège’s 19th-20th
century serial-linear tissues
Matteo Ieva »

From urban nodalities to urban fringe belts.
The case-study of Krakow
Marco Maretto »

Urban growth of Turkish cities
Tolga Ünlu »

The Hybrid, the Network City and the Territory
“elsewhere”.The contemporary “fringe” condition in
north European urban phenomena
Nicola Marzot »



Giuseppe Strappa

The reading of the changes underway at the edges of contempo¬rary cities, where the countryside – often already partly urbanised – densifies and turns into urban matter, is one of the most difficult sub¬jects to tackle methodically. Proof of this is the descriptive literature produced on the topic, where depictions of an inextricable complexity and the suggestion of fragmentation, particularly amongst architects, have become true literary genres in themselves. The obvious obstacle is that the forms in which expansion takes place continuously evolve in time and space and seem beyond any rational, general law, while following a comprehensible process is an essential condition for the construction of a study method that can be communicated (and there¬fore of a design).
The growing complexity of the phenomena that develop on the edges of the built environment, where rural areas prepare for change in ways that seem continually different, can be clearly recognised in post-industrial cities, but the uncertainty inherent in the tools we use to understand and monitor them was already apparent in the post-war period: the very period that attempted to create a limit to the irrational¬ity of cities in chaotic expansion by developing new tools for under¬standing them.
As far back as the 1960s, the Conzenian school offered a clear inter¬pretation of these phenomena, attempting to generalise instances of interpretation developed for individual cities. This method originated in Alnwick’s exemplary study (Conzen, 1960) which, for that matter, we have published in an Italian edition due to the usefulness of the in¬formation it contains. The notion of fringe belt, which arose with these geographical studies – and initially fell on deaf ears (Whitehand, 1996) – was taken up with greater conviction in recent times, becoming a tool for analysis adopted by both architects and town planners.
The method is based on recognising the urban plan, building types and land use as essential factors in determining the kinds of changes that take place. The common features of one or more of these factors allow us to distinguish fairly uniform areas (morphological regions), allow¬ing us to construct models of expansion where we can distinguish forms and phases.
While the resulting model is spatially fairly simple, based as it is on successive rings that move out from the urban centre, its application to the actual built environment is rendered more complicated by the discontinuity of expansion, which usually occurs in stages of rapid growth alternating with periods of relative construction stagnation. M.R.G. Conzen discovered the link between these various phases of consolidation of the urban perimeter and the particular features of building types and land use that determine its form. This is interpreted as the relationship between the result of centripetal forces – particu¬larly obvious in the formation of the inner nucleus, the Central Busi¬ness District (CBD) – and centrifugal forces that push out towards the edges, infrastructure that does not require immediate access, as well as low-density single-family housing.
This relationship between phases allows us to define the concept of ‘fringe belt’ as one that is linked to an urban phenomenon that recurs over time, that takes place at the margins between urbanised and rural areas when the growth of housing fabric stops or slows down abruptly, allowing the consolidation of urban structures through services and infrastructure encouraged by the low cost of these areas and the avail¬ability of land. In other words, some elements of the urban structure tend to be located on the margins of the built environment, creating specialised areas ‘around’ housing fabric.
From the many studies that have been carried out, it is clear how the term ‘around’, whose meaning seems inextricably linked to the term ‘belt’, should actually be interpreted as a spatial hierarchisation rather than in its geometric meaning. To the point where there are many examples of growth across urban nuclei scattered throughout a territory, each of which forms its own fringe belt, before merging and forming new urban entities (see a number of the cases published here).
The fringe belt concept, which emerged with the interpretation of historic cities and is often usefully applied to the study of walled cities (Whitehand, 2017), also seems to contribute to the study of both the growth of industrial cities as well as the more complex expansion of modern-day metropolises.
In fringe belt foundation studies, particularly in the English-speak¬ing world, the benchmark example is the British metropolis, particu¬larly London. If, however, we consider the illegal urban sprawl typical of Mediterranean metropolises, consisting of detached houses on the edges of rapidly expanding housing areas, or the ‘informal’ expansion of South American and Asian cities, it becomes clear how, in many ways and with the proper caveats, the behavioural model features sig¬nificant analogies.
Saverio Muratori clearly noticed, during the same period as Conzen’s research, the condition of crisis that saw post-war cities expanding chaotically and attempted to include them in efforts to trace the myr¬iad urban phenomena back to a common interpretation, to a rational whole that could be taught and passed on (Muratori, 1963).
In the wake of his teachings, Gianfranco Caniggia provided us with a theoretical model of the forms of urban expansion that was very different to that of Conzen but that could be traced back to the same concepts when it comes to some of his general principles. What are, deep down, the infrastructures that are located on the margins of cities in the Conzenian model, that occupy the empty spaces consisting of cheap land if not the Caniggian model’s ‘anti-polar’ construction? And yet, Caniggia seems to refer, above all, to pre-industrial, organic cities that grow according to a modular law, through successive doublings, where each module is part of a larger urban organism and contributes to its life whilst nevertheless maintaining its original characteristics as a distinct and recognisable sub-organism. If we insist on a comparison, ‘mixed land use’ areas can be equated to the peripheral arrangements of partially specialised sub-organisms, in direct contact with rural ar-eas, that form during static phases of city construction.
Both these interpretations, which complement each other in the interpretation of fundamental aspects of the expansion of European cities, are products of the cultural areas where they formed. However, both have been recently adapted – more or less explicitly – to the study of other urban areas, such as those of North America or China, which feature very different characters.
In the early 1960s in North America, specific areas of growth were identified in the expansion on the edges between cities and countryside areas. Gerrit Wissink attempted to classify their typical features with specific characteristics in areas adjacent to the city ‘suburbs’, and more isolated ‘satellite’ areas in the territory, also considering their variations: ‘pseudo-suburbs’ and ‘pseudo-satellite’ areas (Wissink, 1962).
The study method that had to be employed when interpreting North American urban areas had to take into account particular condi¬tions. The differing mechanism of land value almost always hinders the formation of a fringe belt that can be spatially recognised as a single unified whole. There, a strip of available cheap land where anti-polar infrastructure can be set up rarely forms. The increase in land value, determined by the advantages that a particular location offers, begins decades before such land is actually exploited for construction, hin¬dering that clear difference between rural and urban land values that








Fig. 1 – San Martin das Flores in the state of Jalisco, Mexico. Sixteenth-century Spanish settlement turned into slums by the uncontrolled growth of Guadalajara.

encourages the formation of distinct strips of anti-polar construction. Moreover, one should take into account the fact that the greater or lesser marginality of areas of potential city expansion does not depend on their distance from the centre, but rather on complex factors, in¬cluding their accessibility, which has relevant influence, due to the very nature of American cities.
This situation leads to an early division of properties and a change in the size of building lots, smaller near areas of expansion but with a significantly higher value. The development of fringe belts here is therefore less continuous and often opposite to development in radial strips, sometimes following a linear, though discontinuous, form of expansion along transport arteries and, at other times, a growth of ‘clusters’ scattered throughout the territory, depending on a method intrinsic to the market-driven rationale of intense speculative activity and few town planning regulations.
The distance from one’s workplace, often located in the CBD or at its edges, combined with the extensive use of private transport and the formation of associated large-scale infrastructure, contributes to the complexity of this multi-faceted model of growth that is so hard to generalise. Thus the concept of the rural-urban fringe (R-U fringe) emerg¬es, understood to mean the transitional zone that, in Western cities, indicates a discontinuous territory and a contradictory landscape on the border between city and countryside, made up of extensive areas featuring specific, recognisable characters. One character that is usu¬ally identified with R-U fringe is due to the particular condition of its inhabitants, who live there despite not being part of the place either economically or socially (Herington, 1984). It is, moreover, a structural phenomenon linked to the inexorable growth of the urban population, which has for some time now overtaken the rural population (over 54% in 2017), with a percentage growth that seems relentless. This explains the renewed interest in the concepts of ‘fringe belt’ and ‘R-U fringe’, which still seem suited to interpreting the new, uncontrolled phenomena (that are, nevertheless, dynamic and innovative) of the market-led expansion of cities, where new anti-polar structures are often placed beyond the immediate administrative limits not only of large cities but also of small towns, in peri-urban areas that are hardly regulated, occupied by a combination of detached single-family houses and large entertainment complexes, commuter districts and noisy small businesses that cities push to their margins, areas used by undertak¬ers and warehouses of all kinds, shopping malls and venues for large events, concerts and festivals along the edge of farmland. The fact that concepts that have now become traditional, such as those of the fringe belt and R-U fringe have, for some time now, been placed at the centre of design project instruments for areas in urban expansion, succinctly tackling spatial as well as political and social problems, is proof of the attempt to establish the latest town planning frontier, limiting the fragmented city (Gallent, 2006).
However, we cannot deny that the idea of limits, which once con¬stituted one of the pillars of urban studies from the post-war period on, is now definitively in crisis, together with that of a perimeter, which was not only used as a planning tool but also as a mindset, allowing us to establish distinctions and borders.
Nevertheless, I believe that architects and town planners are not al¬lowed to accept reality as it is (contrary to the aesthetically pretentious movement that has recognised in the disintegration of every order the representation per se of the modern world). Often disorder, if ob¬served methodically, contains its own explanation, multifarious aspects of manmade principles that can be recognised and analysed rationally.
In any case, the model used to interpret and critically explain the phenomena of urban expansion is not just a scientific tool: it is also knowledge in action, it contains a design project. I believe we need to ‘designedly’ seek out the form of cities that expand, even in their seem¬ingly chaotic, formless parts (Strappa, 2012).
This book compares and contrasts a number of essays on urban expansion that examine case studies located in various different geo¬graphic areas: from Europe to Asia, from North to South America.

Fig. 4 – Spontaneous ridge routes in the expansion of Mexico City.

It is not, however, just a comparison of urban samples. What interests the editor is to compare interpretational models derived from experi¬ence that come under the umbrella of Urban Morphology, developed in different cultural contexts that nevertheless share the conviction that the form of a city, even in its most seemingly chaotic incarnations, can be interpreted rationally and contains the seeds of future change.

Caniggia, G., Maffei, G.L. (1979) ‘Composizione architettonica e tipo¬logia edilizia 1.Lettura dell’edilizia di base’ (Marsilio, Venezia).
Conzen, M.R.G. (1960) ‘Alnwick, Northumberland: a Study in Town- Plan Analysis’ (Institute of British Geographers, London).
Gallent, N., Andersson, J., Bianconi, M. (2006) ‘Planning on the Edge’ (Routledge, London).
Herington, J. (1984) ‘The Outer City’ (HarperCollins, New York).
Lammers, D., Pereira Roders, A., Van Wesemael, P. (2016) ‘Radial fringe belt formation’, Proceedings of the 22nd ISUF Conference, Rome 2015 (U+D, Rome).
Muratori, S. (1963) ‘Architettura e civiltà in crisi’ (Centro Studi di Storia Urbanistica, Roma).
Strappa, G., ed., (2012) ‘Studi sulla periferia est di Roma’ (FrancoAnge¬li, Milano).