Social infrastructure and the public life of cities: Studying urban sociality and public spaces

Libraries, laundrettes, and lidos. Pizzerias, plazas, and play-grounds. Sidewalks, swimming pools, and schools. These are just some of the kinds of spaces and facilities that contribute to the public life of cities. Drawing on the arguments of the sociologist Eric Klinenberg, this article develops the concept of “ social infrastructure ” as a way to research and value these kinds of spaces. Social infrastructure helps in recognising the public dimensions of often overlooked and undervalued spaces. It draws attention to the breadth, depth, and textures of sociality that can be afforded by different urban environments. In developing the concept of social infrastructure, this article pulls together four related strands of social scientific inquiry: work on infrastructure; publicness and public space; sociality and encounter; and the politics of provision. An infrastructural approach to the topic of public space presents geographers with some productive tools for understanding the public life of cities.

character. In Palaces for the People, the sociologist Eric Klinenberg (2018) makes the argument that a whole range of physical and institutional infrastructures are crucial for the development and maintenance of social connections. This is an argument for social infrastructure. That is, an argument for the role places such as libraries, parks, sports facilities, schools, and community centres play in making a good city and recognising the critical contribution they make to the social life of cities. These places matter as they are sites where strangers can meet and mix with others with whom they share their neighbourhoods and cities. More than just fulfilling an instrumental need, they are sites where cities can be experienced as inclusive and welcoming. For Klinenberg, social infrastructures are necessary for nurturing public life, but also for addressing and preventing some of the most pressing concerns of contemporary urban life: countering social isolation, negotiating difference, and creating places for all-regardless of age, race, gender, sexuality, or income. To think about social infrastructure is to provide an intellectually robust account of how and why places like libraries, parks, community centres, lidos, and even cafes matter for the collective public life of cities.
This article makes an argument for the study of social infrastructure. This is based on our research that has grappled with the value of places like gyms, cafes, skate parks, swimming pools, and football fields and attempted to articulate why these places matter. It is a situated approach building on our research in Europe, North America, and New Zealand but is an approach that connects with others researching similar issues in other parts of the world (Berney, 2017;Sennett, 2017;Simone, 2010). Thinking about social infrastructure involves bringing together four related strands of social scientific inquiry. Firstly, the paper considers what infrastructure is and how it supports social life.
Secondly, it explores the interrelated nature of "publicness," public life, and public space. Thirdly, it focuses in on the socialities of urban life. And, finally, it helps to develop a prospective politics of provision: a politics that relates to how cities are planned. In short, this is to argue for an infrastructural approach to the public life of cities.

| INFRASTRUCTURE, SOCIAL INFRASTRUCTURE, AND HOW TO STUDY IT
Infrastructure has emerged as a central focus in social and urban theory. Within geography, much of this work owes a debt to Marvin's (1995, 2001) work on the physical infrastructures of water, power, transportation, and telecommunications provision. They argue that changing forms of infrastructural provision have created an increasingly splintered landscape where some groups are systematically excluded. Here, physical infrastructure represents "congealed social interests" (Graham & Marvin, 2001: 11, citing Bijker, 1993. Similar arguments have been advanced by Gandy (1999Gandy ( , 2005Gandy ( , 2014) who talks of infrastructure as a kind of cyborg which is a physical morphological entity but is also entwined with political and cultural dynamics. Developing the domestic dimensions of infrastructure, Kaika (2004) highlights how infrastructure reaches into the private sphere of the home (Birkenholtz, 2010;Button, 2017;Chelcea & Pulay, 2015). And Heynen, Kaika, and Swyngedouw (2006) examine the ways nature and infrastructural networks are part of an entangled political economy (Ioris, 2012;Silver, 2016;Swyngedouw, 2009). Of course, urban infrastructures are not uniform. Graham and McFarlane (2015) discuss the diverse ways infrastructures function across the Global North and South. They also make the observation that there is a sociality to this nonsocial infrastructure. A lot of informal human, political, and cultural work gathers around and goes into infrastructure (Amin, 2014;Cesafasky, 2017;Truelove, 2011). Simone (2004) has taken this argument further, arguing that people themselves can be understood as infrastructure: They help the economy, communications, power, and water of cities to function (McFarlane & Silver, 2017). Much of this work comes in the context of radically uneven and unequal provision of infrastructure that excludes the poor and disadvantaged (Wakefield, 2018)-a kind of infrastructural violence (Harris, 2013;Rogers, 2012;Rogers & O'Neill, 2012;Salamanca, 2015).
For the above researchers, infrastructure is understood as an integral part of the urban fabric. It is the background technological networks and systems that support urban life. It is technological, material, social, but also-and perhaps most crucially-political. Although often overlooked, infrastructures are a crucial part of how cities function as sociotechnological systems. Further, they are entangled with how socio-economic disparities are maintained and perpetuated. At a conceptual level, the term "infrastructure" is useful precisely because it is about the background structures and systems that allow social, economic, cultural, and political life to happen. With infrastructure, the central dynamic is around the facilitation of activity. That could well be about the facilitation of water distribution, sanitation, electrical power, or communication through hard technological systems, but it can also be about much more than that.
In fact, expanding the scope of what counts as infrastructural has been a feature of work on infrastructure within the social sciences. There is work on infrastructures of public health (Baker et al., 2005), education (Lo, Preston, Anisef, Basu, & Wang, 2015;Vincent, 2006), and even democracy (von Schnitzler, 2016). The concept of social infrastructure is part of this extension. Klinenberg (2018: 17)  In many cases, what counts as social infrastructure has other primary functions other than to promote sociality; however facilitating sociality is an essential component of how they manage to provide their primary function. Moreover, social infrastructures may exist to amplify connections within groups, and they can also orientate people towards interacting across difference (Blommaert, 2014;Klinenberg, 2018). In developing the term social infrastructure, Klinenberg is building on and connecting with earlier writers such as Putnam (2000), who talked of a society's "civic infrastructure" being nurtured by informal social networks, and Oldenberg's (1989) work on "inclusively sociable" spaces like restaurants, diners, hair salons, cafes, and stores for building trust and community. This work itself connected with a long-particularly American-tradition of ethnographic work on neighbourhood and community life (Cavan, 1966;Gans, 1962;Jacobs, 1961;Liebow, 1967). In short, social infrastructure refers to the networks of spaces, facilities, institutions, and groups that create affordances for social connection.
The above gives a working definition of infrastructure and social infrastructure. However, to study infrastructures more closely, some heuristics are useful. The work of Star (1999) is a good starting point. Working within science and technology studies, Star's central insight is that infrastructures are not just material entities-they are also practiced and relational (Bateson, 1972). This means that infrastructure has a number of properties (Star, 1999;pp. 381-382).
Infrastructure "is embedded"-it exists within established networks and relationships. For example, a library, as a social infrastructure, is embedded within networks of book distribution and recognisable relationships of lending and borrowing (Mattern, 2014(Mattern, , 2015. It "is transparent"-when being used, infrastructure is not necessarily noticed. Sticking with the example of libraries, each time you borrow a book, there is no need to renegotiate the terms of the loan. An infrastructure "has reach or scope"-in other words, it can be used repeatedly. The whole point of a library is that it-and what is being loaned-is durable over time. How to use an infrastructure is "learned as part of membership." What Star describes as the "taken-for-grantedness" (p. 381) of infrastructure involves a process of learning: It is necessary to learn how to use and behave in a library. It "links with conventions of practice"-there are all sorts of norms and routines that affect how infrastructures function and are used. As the world has become increasingly digital, libraries have had to provide new kinds of facilities for people working, studying, and reading. Infrastructures also involve the "embodiment of standards." They work because they are able to draw on existing standardised ways of carrying out functions and designing components. For example, at a very basic level, libraries are able to function because they can plug into standardised infrastructures for heating, lighting, plumbing, and telecommunications. Further, infrastructures are "built on an installed base"-they exist within the context of existing structures of provision.
Libraries have inherited the function of lending books, but this is by no means all that libraries do in the contemporary world. Another property of infrastructure is that it "becomes visible upon breakdown." A lot of infrastructural work goes on in the background, and it is not necessarily noticed until it is no longer functioning. You do not notice all of the social connections a library can help facilitate until the library has closed down. And, lastly, infrastructures are "fixed in modular increments." Because they are "big, layered and complex" (p. 382), it is not possible to change them instantly but only incrementally across the network. For example, if we wanted to change what public libraries provided and were used for, this is something that would take time to embed within the existing uses of the library.

| AN INFRASTRUCTURAL APPROACH TO PUBLIC LIFE
Social infrastructure involves thinking about the different kinds of facilities necessary for cities to function as social spaces. Central to this is that these facilities serve distinct functions. Libraries are places to borrow books. Lidos are for swimming outdoors. Leisure centres provide space to exercise. Markets sell produce. And schools educate children. These are all important functions that people make use of while living in cities-creating the affordances for urban inhabitation. Furthermore, they are spaces where people socialise and make connections with others. They are also-in different and varying ways-public spaces. They are spaces that are publicly accessible. Spaces where people encounter strangers. And spaces that in some cases involve forms of collective provisioning.
The term public refers to a number of qualities and dimensions of collective life. Firstly, and most intimately, it refers to the idea of being out amongst other people (Goffman, 1971;Lofland, 1973). This is important because it is about the affordances and capacities for particular individuals from different social backgrounds to go about their day-to-day activities freely and without barriers. Secondly, in a more outwardly directed kind of publicness, the term can refer to addressing an audience and participating in discussions about the concerns of a community. It is about participating in a public sphere, which may be face-to-face or mediated by communications technologies (Berman, 1999;Habermas, 1989). These first two dimensions of publicness may involve forms of claim-making, but they may equally involve the ways people come to accommodations with each other (Iveson, 2007;Koch & Latham, 2013). Thirdly, and relatedly, publicness can refer to something that is of concern to a community or society-what Marres (2012), following Dewey, calls "matters of concern." Fourthly, and finally, publicness speaks to an idea of public provisioning: the collective provision of facilities for public or private use. All of this is to recognise that the concept of the public-and publicness-is not a single thing; it is multidimensional. Nor is it simply the opposite of private. As the feminist pragmatist philosopher Elizabeth Anderson (2017; p. 44) puts it, "there is no single public sphere or a single private sphere in society. There are many spheres, and which are public or private depends on who you are." To talk about social infrastructure as public space is to talk about a whole range of spaces-many not conventionally thought of as public space-where these different ideas of publicness can be found and practiced.
The concept of social infrastructure helps us think about the public dimensions of urban life, not least in how it orientates us to how the sociality which is entwined with publicness takes place in certain places and facilities. This publicness includes ideas of encounter (Wilson, 2017), but it is also about the ways communities are built, trust developed, cooperation achieved, and friendships made. Amin (2002Amin ( , 2008 has argued that these forms of urban sociality are reliant and entangled with the design and provision of material elements. Amin's thinking is useful because it highlights the way that the functioning of public and collective spaces is dependent on the production and maintenance of a sense of trust (Amin, 2006(Amin, , 2012. This involves both a basic trust in others using the space, as well as a trust in the provision and maintenance of the facilities themselves-this process partly involves the rhythms of repetitive routines through which public spaces becomes "a patterned ground" (Amin, 2008;p. 12). Thinking infrastructurally then, it is important to consider the kinds and qualities of facilities that allow social life to happen, the kind of sociality that is afforded by them, and how this can be recognised as a kind of public life. This might include the design and provision of novel and exhilarating spaces like swimming pools and climbing walls but also involves thinking about the social dimensions of functional spaces such as bike lanes and sidewalks. Further, it is about questions of managing the relationships between looseness and prescription within spaces (Franck & Stevens, 2007). What is valuable in Amin's argument is that the virtues that can emerge out of this material provision has a quality of "surplus"-out of the shared use of social infrastructure, it is possible to recognise qualities of civic culture, of tolerance, and of collective life. The idea of social surplus helps to articulate the idea that out of pragmatic, practical, social interactions in shared space can emerge a common sense of trust; a sense of the world's plurality which goes beyond the straightforward parameters of any single interaction between individuals (Amin, 2012). Through practically making use of social infrastructure, it is possible to identify an ethics of togetherness (Jacobs, 1961;Sennett, 2017).
Focusing on social infrastructure draws attention to the affordances that particular spaces or facilities offer for inhabitation and social interaction. It involves looking at the communities and networks of association generated through such spaces. It is also about paying attention to the design and provision of particular facilities and how their material qualities shape the activity that takes place within and around them-and there is a clear role for planning here in ensuring quality and diverse provisioning (Talen, 2019). This is not to deny the importance of issues of exclusion, encroachment, and claims making that define much contemporary urban geographic work on public space (Koch & Latham, 2012). This work tells us a great deal about the ways that contemporary urban environments can be grossly unequal, contain all sorts of barriers to entry, and that much commercial and political activity can close down particular kinds of public space (Coaffee, 2003;Madden, 2010;Mitchell, 2003;Németh, 2009;Zukin, 2010).
However, developing the concept of social infrastructure draws attention to a whole range of often overlooked and underappreciated urban spaces-and all sorts of overlooked and underappreciated practices. Klinenberg (2018) defines social infrastructures capaciously. The defining quality is the way it affords socialityespecially across difference. Looking across the work of social and urban geographers, alongside that of sociologists, anthropologists, and planners, there is an enormous variety of research, involving a diverse range of places, that incorporates an idea of social infrastructure (see Table 1).

| THE SPACES AND SOCIALITIES OF SOCIAL INFRASTRUCTURE
Public institutions that are provided publicly and designed as facilities for the general public are an important aspect of a city's social infrastructure, and, unsurprisingly, they have been the focus of much work. Most obviously, these involve places that are explicitly conceived and designed for the public to meet. As Rishbeth and Rogaly (2017) and Barron (2015) have studied, the provision of facilities as basic as street benches can function as sites of conviviality and self-care. In a study of the refashioning of Gillet Square in London, Sendra (2015) observes how the provision (and storage) of a diverse range of materials for table tennis, cinema screenings, and markets has helped facilitate conviviality. A central aspect of how this square works is the role of people: opening the storage containers, putting the materials out, working in the kiosks, and generally being present in the space as a kind of public character. This kind of work has been at the forefront of many researching in the planning tradition, identifying materials, layout, and configuration for facilitating public life (Talen, 2002;Gehl, 2010;Carmona, Tisdell, Heath, & Oc, 2010;NLA, 2015).
Other public institutions like schools and libraries exist to serve specific functions and have a distinct social character. Wilson (2013), in a study of an urban multicultural primary school, found that playgrounds can be places where parents meet and socialise in ways that they might not do so in other social settings (see also Carol, Neal, & Iqbal, 2018). Robinson and Sheldon (2019) have documented the social value of a library under threat of closure, whilst Mattern (2007aMattern ( , 2012Mattern ( , 2014 has documented the multiple forms and ideas of what a library can be, from small microlibraries through to libraries becoming sites that might lend all sorts of things other than books. The importance of a library as a public facility raises questions around who should be involved in the design process and, just how public a library actually is, along with how libraries are valued and evaluated by those who fund them (Mattern, 2007b;Mickiewicz, 2016;Leorke, Wyatt, & McQuire, 2018). What is striking is how dynamic the social space of libraries can be. Far from being settled institutions viewed from a social infrastructural perspective, libraries are remarkably innovative.

Transit
The spaces and infrastructures of mobility.
Middleton (2018) sociologist Elijah Anderson (2011), in his ongoing ethnography of racial segregation in Philadelphia, has examined the way certain commercial spaces become havens of trust and agreeable sociality for working-class black men. This is similar to the kind of sociality that can be found in spaces such as barber shops (Mills, 2013), where something as functional as getting your hair cut takes on new social significance for different communities. Mattern (2018;np) has written about the unique functionality of hardware stores and how they can serve as a site of "competence, intention, utility, care, repair, and maintenance." These are all kinds of commercial outlets that a well-stocked and vibrant high street might provide. Hall (2012) and Hall, King, and Finlay (2017) have studied the way that a successful high street can serve as a vital function and foothold for migrant communities in cities like London. There is an important role for planners here in ensuring a diverse range of stores and land uses (Jacobs, 1961;Talen, 2019). In many of the examples mentioned above, social infrastructure can be an important resource for the economically or socially marginalised. This relates to the work that recognises the ways the liveliness of certain streets and sidewalks connects with shops and similar commercial activity (Hubbard & Lyon, 2018;Klinenberg, 2002). There is also value to be found in the light sociality that can be found in other commercial settings: places like cafes and coffee houses (Henriksen & Tjora, 2018;Latham, 2003;Laurier & Philo, 2006a, 2006bPuel & Fernandez, 2012), restaurants both fast and slow Kärrholm, 2008), bars (Latham, 2005;Lugosi, Bell, & Lugosi, 2010), and social clubs (Conradson, 2003). Commercial spaces designed for particular social groups (such as the LGBTQ+ community) have been important locations for "community life, welfare and wellbeing" (Campkin & Marshall, 2017;p. 4;Taylor & Falconer, 2015;Chauncey, 1994).
Turning away from social infrastructures that are either publicly or commercially provided, it is worth thinking about the social infrastructures that facilitate particular kinds of activities and practices. One important but easily overlooked set of practices are those of amateur sport and fitness (Hitchings and Latham, 2017b;Latham & Layton, 2019b). Parks and playing fields are perhaps the most obvious examples here-and attending closely to the activities that are going on in them reveals distinct kinds of social life. Krenichyn (2004Krenichyn ( , 2006  self-confidence, and community life to happen in the context of courts and gyms. Facilities for swimming, in many cases, map onto a more fraught relationship between strangers' bodies. Wilste (2007) examines the conflicts that accompanied attempts to racially desegregate public swimming facilities in American cities. Iveson (2003) reconstructs a debate about the value of women's-only bathing facilities in Sydney, Australia. Amidst this conflict, the sociality of swimming with others should not be forgotten (Adiv, 2015;Ward, 2017;Worpole, 2000). These issues are also entangled with issues of ownership and provision. Privately provided commercial facilities may well be vulnerable to closure as Jackson (2019) highlights with a bowling alley. However, in economically marginalised neighbourhoods, it is precisely through private provisioning of spaces like dance studios and fitness classes that a practice like Zumba has become a site of public sociality for Latino American women in Los Angeles (Petrzela, 2018;Scott, 2015). Amateur sport and fitness are just one kind of recreation. Other examples might include facilities for community gardening (Barron, 2017;Follmann & Viehoff, 2019;Tonkiss, 2013), amateur theatre (Becker, McCall, Morris, & Meshejian, 1989), or book clubs (Long, 2003).
Depending on the kinds of social infrastructures that are studied, all sorts of communities, social networks, and experiences can be found. For example, cities are full of places of worship. Alongside the rituals of worship, places such as synagogues, mosques, gurdwaras, churches, and temples also facilitate community and social connection (Dwyer et al., 2013;Gilbert et al., 2019). These connections can have social significance for undocumented migrants (Ehrkamp & Nagel, 2014) and even function as a route to civic participation (Levitt, 2008), whilst the physical spaces themselves (much like other social infrastructural spaces like schools and libraries) can double as venues for all sorts of other activity like community meetings, local theatre, fitness classes, and music concerts. In contrast and turning to a different example, thinking with transit in terms of social infrastructure draws attention to a whole set of fleeting but no less significant sites of daily social interaction (Bissel, 2018). Activities as diverse as walking, cycling, and bus passengering have an observable social dimension (Middleton, 2018;Brömmelstroet, et al. 2017;Wilson, 2011). The overarching point is that thinking with social infrastructure broadens and deepens understandings of the kinds and qualities of social life that exists in cities.

| TOWARDS A POLITICS OF PROVISION
The argument this paper has been making is that social infrastructure is an important way that social connection and public life happens in cities. Attending to the diverse spaces, facilities, institutions, and groups that create affordances for social connection can highlight overlooked and undervalued aspects of collective urban life. Central to this is an infrastructural approach: an approach that is sensitive to the way spaces and facilities are designed, maintained, and planned, but also how spaces are practiced and come to be used (Star, 1999). The social connections and socialities that are built and maintained through accessing social infrastructure have real material benefits and consequences; they generate a "social surplus"-encouraging trust, civility, encounter, and common purpose (Amin, 2008). They are in all sorts of subtle ways entangled with maintaining people's physical and mental health (Umberson & Montez, 2010). And as Klinenberg (2002Klinenberg ( , 2018 has studied, social infrastructure can even affect who lives and dies during times of environmental disaster and can be a crucial way to counter political polarisation. This is to make an argument for the provision of social infrastructure and to make an argument for the need to study the politics involved with the provision of social infrastructure. There are a number of dimensions to the provision of social infrastructure that can make it more or less successful. One, the abundance of provision is important. When social infrastructures are difficult to find or only convey a sense of functionality and nothing more, it does not convey a social surplus. A good example is the Palmerston North public library in New Zealand; calling itself "the city's living room," its playful architecture embodies a generous public hospitality that goes beyond simply lending books (Palmerston North City Library, 2012;Stanley & Emberton, 2005).
Two, the diversity of social infrastructure matters. People seek out a range of activities and communities and therefore require a range of facilities and spaces. Thinking in terms of recreational social infrastructure, it would be important to provide a diverse range of facilities that included all sorts of places such as swimming pools, climbing walls, and basketball courts, not only mile after mile of football pitches. Three, how social infrastructures are maintained affects how the provisioning is experienced and how trust is developed. This maintenance is physical; it is about repairing the materials and surfaces as they deteriorate. But it is also social; spaces and facilities need to feel cared for and safe. Four, provision and accessibility go hand-in-hand. For social scientists, working with social infrastructure opens up a number of avenues of critical inquiry. Perhaps the most obvious is studying the spatial distribution of the provision of facilities. If social infrastructure is an integral part of any good city, the concentration of social infrastructure in affluent neighbourhoods becomes a question of social justice (Capps, 2019;Nethercote, 2017  . Similarly, if infrastructure is designed, built, and maintained with only a narrow demographic in mind, this may undermine its function as social infrastructure. It would also be important to consider the way social infrastructures vary around the world and the different kinds of sociality it facilitates (Anguelovski, Irazábal-Zurita, & Connolly, 2019;Chen, 2010;Simone, 2006;Stillerman & Salcedo, 2012;Teo & Neo, 2017). Here, it is important to recognise the role of planning in the design and provision of social infrastructure-researchers might look for exemplary cases of infrastructural provision for otherwise overlooked and underserviced communities (Berney, 2017;Damyanovic, Reinwald, & Weikmann, 2013;Talen, 2019). They might also examine disputes surrounding the planning and provision of social infrastructures to explore how competing claims on social infrastructure unfold and are resolved (Latham & Layton, 2019a).
However, studying social infrastructure is also about studying how they get practiced. This means locating and understanding the spaces and facilities that are facilitating sociality and social connection-making sense of how the spaces and facilities work and exploring the social surplus that might be found in them. This involves recognising the specific value that can be found in spaces and facilities, understanding how and why they matter to the communities that use the space, and how we might understand them as social infrastructures. The mattering that can be found in social infrastructure would include the value of encounter but is also in many instances about being able to go out, use facilities as free citizens, and get on (Klinenberg, 2018). Studying social infrastructure can document what should be protected, curated, and encouraged in urban environments. This is a task of critical importance, considering the context of austerity in many cities-at least in parts of Europe and the United States-where social infrastructures are under stress and risk of closure (Hitchen & Shaw, 2019). Here, as Simone and Pieterse (2017) would recognise, it is important to document and redescribe the conditions that encourage urban life to flourish.

| CONCLUSIONS
Cities need social infrastructure. Cities need places like libraries, parks, schools, playgrounds, high streets, sidewalks, swimming pools, religious spaces, community halls, markets, and plazas not only because of their practical utility but also because they are spaces where people can socialise and connect with others. These spaces matter. They matter not least because they are in all sorts of ways public spaces. They are spaces that create affordances for people to be out amongst other people. They are spaces that are central to what people become concerned with in urban environments. These spaces are also provided-even if by commercial entities-to facilitate shared use and collective experience. Thinking about these kinds of spaces as social infrastructure highlights a range of often underappreciated and overlooked spaces not often thought of as public but which nonetheless have distinct public dimensions. Studying these spaces as social infrastructure-as spaces that facilitate social connection-directs attention to the breadth, depth, and texture of social life that can be facilitated in the urban environment. To go back to Klinenberg (2002Klinenberg ( , 2018, these kinds of spaces matter because of their consequences for society, politics, health, and well-being.
Throughout this paper, we have been making a normative argument for the importance of these spaces. As Klinenberg argues, articulating that these kinds of places matter is an important task-and we would add that as geographers and social researchers, there is a role for us to play in exploring and explaining how these kinds of places matter in multiple and at times unpredictable ways. Their success and proliferation is by no means guaranteed and should be researched further, but reflecting on the times and places where social infrastructure is working can help to build a case for their protection and provisioning.
Thinking infrastructurally draws attention to the ways all of the above places and facilities are provisioned and practiced. Infrastructure is about the facilitation of activity. The material qualities of social infrastructure is central -the way it is embedded within networks, has a modularity, exists within conventions of practice, and affords certain kinds of activity and use. The design, maintenance, distribution, and qualities of what is provided affects how social infrastructures function. There is a clear role for social scientists in making sense of-and articulating-how these infrastructures come to be practiced, and why they matter. The value of social infrastructure is often not immediately visible. Its absence is often only noticed when something goes wrong or when it has been taken away. For these reasons, it is important to remind ourselves why social infrastructure matters. Advocating for these spaces is helped by documenting how social infrastructures function and how they can be experienced as democratic and fulfilling. To study social infrastructures is to study one way that the good city might be realised.