From London to Mumbai, how hostile architecture turns public space into a system of quiet exclusion
I. The Invisible Arsenal and the War Over Words
In June 2014, photographs of an entrance alcove on Southwark Bridge Road in London provoked widespread public controversy. Embedded into the concrete outside a residential building were rows of metal studs designed to make the ground difficult to occupy. The public response was immediate. Images of the studs triggered demonstrations and calls for their removal, and then-Mayor Boris Johnson publicly demanded that they be taken down. Elsewhere in London, activists responded to the wider controversy with direct interventions of their own (ITVX; The Guardian).
Across cities, these interventions have taken a varied physical form, documented across the literature on hostile design (Robert Rosenberger; Cara Chellew):
- Divided and segmented seating: public benches fitted with intermediate steel armrests, central loops, or vertical flanges that break a continuous surface into individual perches.
- The Camden bench: a sculpted concrete bench commissioned by Camden London Borough Council and manufactured by Factory Furniture. Its ridged and sloping surfaces were designed to make rough sleeping difficult and discourage other forms of anti-social use (The Guardian), while its smooth, treated surfaces reduce litter accumulation and resist water, graffiti, and fly-posting.
- Sloped perches and leaning bars: transit waiting ledges and bus shelters fitted with steeply angled boards that allow a commuter to lean but make lying down difficult.
- Surface studs and spikes: metal hardware fastened to window sills, ventilation grates, and low boundary walls.
- Defensive landscaping: large boulders placed beneath highway overpasses, dense thorny planting beds along building perimeters, and modular planters positioned to disrupt continuous pedestrian gathering.
- Infrastructural removal: the removal or omission of amenities such as public benches, water fountains, and restrooms, producing exclusion through absence.
The distinctions matter because the same physical object can serve different purposes: preventing sleep, preventing skating, controlling circulation, protecting property, or simply making prolonged occupation uncomfortable. The terminology used to describe these objects remains contested. Academic research by scholars including Robert Rosenberger, Cara Chellew, and Karl de Fine Licht examines how terms such as hostile, defensive, disciplinary, excluding, and unpleasant design reflect different intentions, physical mechanisms, and moral implications. The term “defensive architecture” emphasizes protection, crime prevention, and the management of unwanted use, while “hostile architecture” and “exclusionary design” are often used critically to emphasize who may be excluded.
II. The City That Controls Behaviour
Hostile design overlaps with a much broader tradition of using the built environment to influence human conduct. Crime Prevention Through Environmental Design, known as CPTED, is one major strand of that tradition, developing the principle that physical spatial arrangements can affect crime, surveillance, and territorial control (Property Management / Emerald). But hostile design should not be treated simply as a later or punitive version of CPTED. The scholarship on behavioral design emphasizes that defensive, disciplinary, and hostile features represent distinct approaches to managing public spaces (Karl de Fine Licht).
Rather than inviting communal presence to foster natural oversight, some defensive installations are intended to prevent specific forms of prolonged presence, such as sleeping or lingering. The mechanism is straightforward: a spatial intervention changes what the body can comfortably do, which changes how long a person can remain or what kind of activity can take place there.
Beyond physical hardware, cities and commercial operators deploy sensory and environmental measures:
- Acoustic dispersal: commercial premises and transit hubs broadcast classical music into concourses, transit stations, and parking areas as an audio-affective deterrent to discourage lingering, an intervention analyzed in research on weaponized soundscapes from the Open University.
- High-frequency deterrents: devices marketed under names such as “The Mosquito” emit acoustic tones around 16 to 18.5 kHz, which are typically more audible and irritating to adolescents than to older adults due to age-related hearing decline, an effect documented by the Council of Europe Parliamentary Assembly.
- Wetting down: water spraying and washing practices used to make sheltered alcoves or pavement unusable for rough sleeping, documented in parliamentary research on rough sleeping enforcement powers by the House of Commons Library.
These measures can also operate alongside one another. Physical barriers may make prolonged rest difficult, while surveillance and enforcement can further restrict how long particular users remain in a space.
III. Who Is Being Designed Out?
While public discussion frequently focuses on defensive design as an anti-homeless measure, the academic literature treats hostile design as a wider behavioral filter, with documented targets extending beyond people experiencing homelessness to groups such as young people and skateboarders (see Robert Rosenberger’s “Hostile Design” in Oxford Bibliographies in Urban Studies).
In suburban Melbourne, Australia, a 2025 study in the Journal of Applied Youth Studies examined redesigned railway stations at Lilydale and Mooroolbark. Conducting visual and documentary analysis without human participants, the study identified how seating alterations, rough materials, surveillance cameras, and segmented public areas constrained young people’s opportunities to gather. The authors interpreted these architectural choices within broader policy narratives that portray congregating youth as threats to public order.
The same logic appears outside anti-sleep design. Anti-skate elements attached to railings and planter ledges deliberately restrict skateboarders from using those surfaces (Robert Rosenberger; Cara Chellew). In commercialized public spaces, the absence of amenities and modification of seating or ledges can also restrict uses that fall outside expected functions (Robert Rosenberger; Cara Chellew). Taken together, these cases widen the question beyond homelessness: who is allowed to remain in a space when their presence is not tied to consumption, transit, or another officially sanctioned activity?
IV. The Global City
The same design logic takes different forms when it meets different legal systems, transport networks, property regimes, and ideas about who public space is for.
London
The 2014 spikes controversy also drew attention to less conspicuous forms of defensive design, including the Camden bench and other forms of exclusionary street furniture (The Guardian). While the Vagrancy Act 1824 was repealed on 29 June 2026 and replaced by new targeted offences (GOV.UK Circular 004/2026), forms of defensive street design were already established features of London’s public-space debate (The Guardian). The wider English context was nevertheless marked by a record-high rough-sleeping snapshot: 4,793 people were estimated to be sleeping rough across England on a single night in autumn 2025, although London’s own figure fell by 3 percent to 1,277 (GOV.UK Statistics). By contrast, as of September 2026, an official UK parliamentary petition seeking a direct ban on hostile architecture had received 55 signatures, well below the 10,000-signature threshold for a Government response and the 100,000-signature threshold for parliamentary debate (UK Parliament Petitions).
Paris
At the Gare du Nord railway terminal, major renovations reshaped the passenger concourse. As reported by Le Monde, rail authorities removed flat wooden benches, installed metallic dividers across remaining seats, enclosed alcoves where rough sleepers gathered, dismantled external sheltering awnings, and cordoned off conditioned waiting lounges for ticketed passengers. Station management defended these steps as operational measures to optimize passenger circulation and improve the transit experience. In doing so, Paris demonstrates how defensive design extends into the management of waiting itself: defining who may remain in a transport hub, for how long, and under what conditions.
New York City
Section 37-741 of the New York City Zoning Resolution sets standards intended to facilitate abundant, comfortable, and accessible seating in public plazas. In January 2026, city lawmakers introduced Introduction 0308-2026, a proposal that would direct the Department of City Planning, in collaboration with other agencies, to study the extent of hostile architecture and compliance with public-plaza seating requirements (New York City Council).
Tokyo
In Tokyo, public attention has focused on subtle forms of environmental design. In 2020, The Japan Times reported on the widespread use of bench dividers and narrow metal perches intended to discourage people from lying down. In March 2024, a curved bench in a Shinjuku park drew criticism after social-media users interpreted its design as discouraging homeless people from lying down. Local officials said it had been installed in response to complaints about drinking, loud conversation and prolonged use (TV Asahi News). The episode illustrates how an installation justified in terms of drinking, noise, and prolonged use can nevertheless function as a physical barrier to lying down or extended rest.
Toronto
In Ontario, the grassroots documentation project DefensiveTO cataloged defensive features across the Greater Toronto Area. Their mapping documents divided benches, window-ledge modifications, transit perches, and omitted municipal amenities, highlighting the range of groups whose use of public space can be affected by such designs (DefensiveTO).
Melbourne
The suburban station redevelopments at Lilydale and Mooroolbark, analyzed in the Journal of Applied Youth Studies, show that defensive securitization is not confined to dense urban cores. By incorporating spatial barriers, rough materials, and extensive camera surveillance into suburban transport nodes, the station redevelopments embed physical and disciplinary measures that regulate young people’s presence, constraining their ability to gather, socialize, and remain in public view.
Mumbai
Mumbai brings the question into a city where the pavement is not merely a route between destinations but, for some residents, an essential part of everyday domestic life. In March 2018, public controversy prompted an HDFC Bank branch in the Fort commercial district to remove sharp iron spikes that had been embedded into its exterior granite plinth (India Today). Local reporting also documented pointed granite studs and metal bars installed along low boundary walls in the affluent neighborhood of Pali Hill in Bandra to deter domestic workers, drivers, and vendors from sitting (Scroll.in).
Paroj Banerjee’s ethnographic research makes the issue concrete: for some Mumbai footpath dwellers, the pavement functions not simply as circulation space but as a site of domestic life, where residents cook, store possessions, and maintain social spaces directly on footpaths (Wiley Online Library).
This context complicates contemporary municipal projects. In September 2026, the Brihanmumbai Municipal Corporation announced plans to widen and revamp footpaths on 30 roads in the eastern suburbs after removing what it described as illegal encroachments, with the stated aim of improving pedestrian circulation and walkability (The Indian Express). The documented project is framed by the BMC as a walkability and pedestrian-circulation intervention. The harder policy question is what happens when reclaiming space for those purposes affects vendors or other informal users who already depend on it.
São Paulo
Beneath city viaducts in São Paulo, municipal subprefecture workers installed rough concrete blocks and rocks with mortar to prevent unhoused people from camping. The intervention drew national attention when Father Júlio Lancellotti, an advocate for homeless people, publicly dismantled the stones with a sledgehammer, turning the site into a prominent symbol in Brazil’s subsequent debate over hostile design (Folha / UOL).
V. When Public Space Stops Being Public: The POPS Mechanism
In New York City, more than 590 Privately Owned Public Spaces, known as POPS, across more than 380 buildings provide over 3.8 million square feet of public space (NYC Department of City Planning). POPS originated in 1961 as part of New York City’s incentive-zoning system, which offered developers additional floor area in exchange for creating publicly accessible spaces such as plazas and arcades (NYC Department of City Planning).
Section 37-741 of the New York City Zoning Resolution sets standards for abundant, comfortable, and accessible seating in public plazas and prohibits devices or forms incorporated into suitable seating surfaces that are intended to prevent or inhibit seating. However, because POPS remain privately owned while being required to provide public access, questions about speech, assembly, and the enforcement of private rules have generated legal disputes and commentary, including the First Amendment issues surrounding Zuccotti Park analyzed by Sarah Kunstler in the Fordham Urban Law Journal. Private owners may also use private security personnel to enforce site rules, a practice examined in research on publicly accessible spaces by Jeremy Németh and Stephan Schmidt in the Journal of the American Planning Association. New York City’s administrative code requires recurring inspections and annual reporting on complaints, enforcement actions, and closures (New York City Administrative Code § 25-114); separate research and reporting have documented restricted access, missing amenities, and other forms of non-compliance (Art Law).
VI. The Cost of Staying: Lived Experience and Collateral Damage
The consequences of a divided bench depend heavily on what alternatives a person has. For someone with a home, discomfort may end when they leave the space. For someone without shelter, the same design can affect where they rest, wait, store belongings, or spend the day.
Lived Experience
A 2026 ethnographic study in the Journal of Social Distress and Homelessness interviewed 19 people with lived experience of homelessness in Washington, DC. The study found that participants described physical discomfort, limits on daily activities, reduced social networks, and effects on emotional and psychological wellbeing while navigating hostile architecture (Taylor & Francis Online).
A 2025 qualitative study of 15 unhoused individuals published in Ethnography documented how design features such as divided benches, music installations, and fenced boundaries shape daily routines. Participants described exclusionary design as a source of rejection, stress, and pressure to move through or away from particular public spaces (Sage Journals).
A 2025 conceptual paper in Cities & Health argues that displacement associated with hostile architecture could worsen health risks by pushing people toward less safe environments, while emphasizing that direct empirical evidence remains limited (Taylor & Francis Online).
The Accessibility Paradox
Defensive measures often affect the wider public as well. Architectural researchers at the University of New South Wales have argued that benches modified to prevent sleeping frequently make ordinary sitting more difficult for older people, pregnant women, and individuals with physical disabilities (UNSW Sites). When seating is deliberately made less usable for prolonged rest, people who depend on public seating for ordinary breaks may also experience the consequences.
VII. Does It Actually Work? The Evidence on Deterrence vs. Displacement
Taken together, the cited research provides clearer evidence of the deployment of hostile design to discourage sleeping, and of localized displacement in some observed cases, than of any population-level effect on homelessness. In a survey of 115 transit agencies across the United States and Canada, the UCLA Institute of Transportation Studies found that about half used structural elements or landscaping to discourage sleeping at stops or stations (UCLA Institute of Transportation Studies; ScienceDirect).
That distinction matters. Evidence that a design discourages use at one location does not by itself establish that the underlying activity has disappeared. The research literature also shows why effectiveness is difficult to measure: transit homelessness programs can be evaluated against competing objectives, from reducing the number of unhoused people in transit systems to connecting people with shelter, housing, or services (Transportation Research Record). The sources cited here do not establish a population-level reduction in homelessness.
A street-level example points to the same distinction between local deterrence and broader resolution. A 2023 San Francisco Chronicle block-by-block survey found that where sidewalk planters had been installed, encampments usually remained nearby, sometimes across the street or around the corner (San Francisco Chronicle). The examples therefore reinforce the central evidentiary distinction: displacement from one location is not evidence that the underlying problem has been reduced (ScienceDirect).
VIII. Contestation and Legal Response: Activism, Redesign, and Brazil’s Statutory Ban
Civic opposition to hostile design has developed through both direct public action and statutory reform.
Tactical Urbanism and Direct Action
Grassroots groups have challenged spatial exclusion through direct interventions in the public realm. The activist group Space Hijackers engaged in “guerrilla benching” actions, protesting municipal seating removals by constructing and placing benches in public areas (ETA). In the arts, British artist Stuart Semple launched the “Design Crimes” campaign, distributing warning stickers for citizens to place on hostile benches and spikes to draw public attention and prompt public scrutiny (99% Invisible).
Statutory Legislation: Brazil’s Padre Júlio Lancellotti Law
Brazil provides a prominent national statutory response through Law 14.489, known as the Padre Júlio Lancellotti Law (Planalto). Enacted on 21 December 2022, the federal statute amended the national City Statute to prohibit hostile construction techniques in open spaces for public use. It mandates that public installations promote comfort, rest, and accessibility, while prohibiting materials and structures whose objective or result is to drive away unhoused people, older citizens, and youth. Brazil therefore provides a concrete example of hostile design becoming a matter of national statutory regulation rather than remaining solely an architectural or municipal-policy dispute (Planalto).
IX. Who Gets to Belong? The Public Square Paradox
Across the cases examined here, public space is generally easiest to accommodate when users are moving, consuming, commuting, or otherwise engaging in expected activities. Those who remain outside those uses can encounter fewer places designed for prolonged presence.
Hostile architecture can make the management of public space visible in physical form. The deeper question is what cities choose to do when homelessness, informal activity, or prolonged public presence conflicts with demands for security, cleanliness, circulation, or commercial use.
Not every barrier or security feature represents hostility. Handrails prevent falls, bollards stop vehicles from mounting sidewalks, and maintenance fencing protects fragile municipal infrastructure. The challenge lies in distinguishing legitimate safety and crowd management from designs whose primary consequence is social exclusion.
The question, then, is how the physical rules of public space can leave room for people whose lives cannot be accommodated entirely within private property or commercial transactions.
