On borders. An operational proposal for a sustainable city

The paper intends to serve as a theoretical-operational proposal in the field of urban morphology and the study of city phenomena, starting from the demands of goal 11 of the 2030 Agenda for Sustainable Development. In particular, the 10 targets set by the 2030 Agenda are instrumental in resolving the trade-off between the efficiency of city life and the healthiness offered by rural conditions. Although the problematic relationship between city and nature has emerged with particular topicality as a result of the health emergency, it has its roots in the distant past. An example of this is the provocative thesis of the “culture of congestion” proposed by Rem Koolhaas in 1978 in reference to the urban experience lived by man in most of the world’s metropolises, a precursor to the crisis that the proximity condition linked to metropolitan life reached with the outbreak of the epidemiological situation. The problems of the city that have emerged from the state of emergency of the last two years should be read with reference to the ever-present, and never resolved, relationship between the forms of the built and the forms of the natural open space. In response to these and other solicitations (for example, the UN’s World Urbanization Prospects report in the 2014), a part of contemporary architectural and urban culture seems to be challenging the trend towards urbanisation. In Italy, Stefano Boeri and Massimiliano Fuksas, in the light of the Covid-19 pandemic, propose a scenario centred on the “flight from the big metropolises” in favour of resettlement in small historic and rural villages, whose actual advantages, however, should not be discussed so much as their feasibility in economic, social, environmental and above all urban-architectural terms. Indeed, it is clear that this strategy sidesteps the main critical issues that are well highlighted in the 2030 Agenda: for example, reducing the negative environmental impact of cities, particularly in terms of air quality and the provision of large, inclusive and accessible green spaces, so that they become, as Sennett affirmed, “healthy and habitable”. Even a staunch defender of the “closed system” of the city, and thus of densification, such as the American sociologist Richard Sennett, as a result of the discomfort caused by the conflict between the occluded spaces of cities and the new needs for distance, has recently argued for the need to embrace new forms of urban life that produce openness. In the essay Città aperte, Sennett’s proposal can be operationally interpreted as the possibility of inverting the paradigm of city construction, moving from a “closed system” to an “open system” in which it is possible to reconcile the city in terms of healthiness and habitability through the grafting of pieces of nature: this relationship between the built and the natural element imposes a rethinking of the “architecture of density”, at the basis of the logic of compact cities. New “physical forms of density”, capable of stimulating economic activity, coping with climate change and allowing individuals to socialise, can be achieved by re-drawing the “borders” of the city. In this sense, it recalls the distinction offered by the biologist Stephen Jay Gould who in natural ecologies distinguishes two types of boundaries: limits and borders. The “limit” indicates where things end; the “borders” significantly represents those spaces where different components interact. If sociologists understand the “borders” as the place where relations between individuals manifest themselves, by translation in the field of urban studies the term refers to that finitezza of relations between urban parts that Giuseppe Samonà mentions when he states that cities must have a limit and the need for urban studies to return to deal with these boundaries. The theoretical field to which the contribution intends to refer is therefore the “city by parts”, where by this locution is meant, recalling the long tradition of Italian urban studies and in particular those advanced by Carlo Aymonino, a city that has acquired new dimensions compared to the past and that, for this reason, can no longer be traced to a single forma urbis but rather to different recognisable parts that have been added to over time. On the basis of these theoretical premises, the contribution focuses on the transformation of the city through the re-drawing of “borders” of its various parts, applying the natural element as a means of distinguishing and enhancing the different morphologies that make up, according to Claude Lévi-Strauss’ well-known definition, “the human thing par excellence”. The case study concerns the city of Palermo. Panormus, a city consolidated in the late Middle Ages and then transformed in the following epochs, is today an exemplum not only of an urban heritage of high historical and cultural value, but also of an Italian metropolis, which has been structured over the centuries mostly through the formation of dense and compact fabrics that are still clearly distinguishable. The goals of Agenda 2030 thus become a pretext for understanding how the definition of green and accessible spaces can be both a structural and transformative condition for making the “city by parts” intelligible and for adopting a model of inclusiveness and sustainability in line with the challenges that the world poses to all those who study the city and its phenomena.