The battle against bacteria has shaped modern architecture, but the health of humans as well as the planet depends on letting the bugs inArchitecture and illnesses have always been entangled. Itcould even be argued that the beginning of architecture is the beginning of disease. As doctor Benjamin Ward Richardson put it when introducing Our Homes and Howto Make them Healthy, a compendium of texts by doctors and architects for the 1884 International Health Exhibition in London: Man, by a knowledge and skill not possessed by the inferior animals, in building cities, villages, houses, for his protection from the external elements, has produced for himself a series of fatal diseases, which are so closely associated with the productions of hisknowledge and skill in building as to stand in the position of effect from cause. Man in constructing protections from exposure has constructed conditions of disease.Doctors and architects have always been in a kind of dance, often exchanging roles, collaborating and influencing each other, even if not always synchronised. Imhotep, the Egyptian architect of the step pyramid of Djoser at Saqqara of 2600 BCE, was also a physician and the author of many medical treatises more than two millennia before Hippocrates, usually considered the father of medicine. Vitruvius in the 1st century BCE launched western architectural theory by insisting that all architects needed to study medicine: Healthfulness being their chief object. He devoted a large part ofhis Ten Books on Architecture to the question of health, giving detailed instructions on how to determine the healthiness of a proposed site for a city by returning to the ancient method of sacrificing an animal that lives there and inspecting its liver to make sure it is sound and firm. Likewise for the health of buildings, he discussed the theory of the four humours, which was the dominant medical theory of the time. Vitruvius even argued that those who areunwell can be cured more quickly through design, rebuilding the system of those exhausted by disease including consumption, now known as tuberculosis.In 1985, architect Lina Bo Bardi curated the exhibition Entreato para Crianas (Interlude for Children). The poster included the architect as a toddler anddrawings of insects alongside the words dont step on the ants, dont killthe cockroaches.Credit:Instituto Lina Bo and PM Bardi / Casa de VidroElsewhere, architects and planners have long waged wars against bugs. InLubumbashi, in the Democratic Republic of the Congo, disease spread by flies and mosquitoes was used byBelgian colonialists to justify a cordon sanitaire. Sammy Balojis Essay on Urban Planning documents its lasting urban legacyCredit:Photo (detail): Alessandra Bello / Courtesy of Sammy Baloji and Imane Fars Gallery, ParisEvery subsequent architectural theory added something to this medical paradigm. Cities represent an accumulation of theories ofdisease from ancient times to the present. The history of architecture and the history of the city is the history of disease, thehistory of a series of structures and infrastructures put in place to counter the previous epidemic, as if it was always a step behind. From new building types, such as the lazaretti in 15thcentury Italy, designed to contain those infected by the plague, or suspected to beinfected, to the great infrastructure works of the 19th century: sewage systems, clean water, urban grids and parks that completely reshaped cities in the name of health.Modern architecture was produced under emergency conditions. Throughout the late 19th century and the first half of the 20th, millions died of tuberculosis every year all over the world. Modern buildings offered a prophylactic defence against this invisible micro-organism, the tuberculosis bacillus that was only identified in1882 by Robert Koch. All the defining features of modern architecture white walls, terraces, big windows, detachment fromthe ground were presented as both prevention and cure. LeCorbusier, for example, wrote that pilotis separated the housefrom the humid ground where disease breeds.Cities represent an accumulation of theories ofdisease from ancient times to the presentTo produce the idea of modern architecture as healthy, 19thcentury architecture was demonised as nervous, unhealthy andfilled with disease, especially the bacilli of tuberculosis. Decorative excess was itself treated as an infection. Modernising architecture was firstly a form of disinfection, a purification of buildings leading to a healthgiving environment of light, air, cleanliness and smooth white surfaces without cracks or crevices where contagion might lurk.It was not until 1928 that the first modern antibiotic, penicillin, was accidentally discovered by Alexander Fleming when he observedthat mould stopped the growth of bacteria, unknowingly reactivating an ancient knowledge; Imhotep had already applied mouldy bread to skin infections, and plants with antibacterial properties have been central to the health practices of many Indigenous communities all over the world for thousands of years. Streptomycin, the first antibiotic effective against tuberculosis, wasnot discovered until 1943 and not widely available for a decade but there was already an antibiotic philosophy of architecture. Modern architecture was the antibiotic. It was modern inasmuch asit was free of bacteria, particularly the bacillus of tuberculosis. Inthat sense, it saved lives.In response to the tuberculosis epidemic in the late 19th and first half of the 20th century, modernist sanatoria prioritised access to direct sunlight.The rooms of Lake County Tuberculosis Sanatorium, built in 1939 to designs by William Ganster and William Pereira and appearing on the cover of Revista Nacional de Arquitectura in 1952 (left), all faced south to maximise sun exposure. In todays hospitals, sky ceilings imitate natural light and vegetation, as captured in Lewis Khans Theatre series (lead image), started in 2014Credit:Colegio Oficial de Arquitectos de Madrid (COAM) and Lewis KhanThe medicinal nature of modern architecture and the unimaginable horror it was responding to has been largely forgotten. We act as if each pandemic is the first, as if trying to bury the pain and uncertainty of the past. In the early days of the Covid19 pandemic in 2020, buildings designed for temporary events hosted an emergency medical architecture, a space for disease. The scene was repeated all over the world, from Belgrade to Lahore, Wuhan toKuala Lumpur, So Paulo to New York City. Vast halls, stadiums, armouries and urban parks were turned into field hospitals. It was not the first time: during the 1918 flu epidemic that killed more people than the two World Wars combined, huge empty spaces werefilled with beds. A photograph of a field hospital in a US armytraining camp in Camp Funston, Kansas, where the 1918 virusfirstemerged, shows hundreds of ill soldiers in a grid of beds inan uncanny resemblance of what would happen a century later. Inhealth emergencies, all buildings are medicalised. Medical crises bring architecture to the foreground.Like antibiotics, modern architecture eventually created its own monsters. It produces sickness, most obviously sick building syndrome. The airconditioning systems that architects such asLeCorbusier celebrated for isolating the inside air from the contaminated outside air turned out to be reservoirs and vectors ofdisease, circulating pathogens. The kind of architecture that wassupposed to inoculate its occupants against disease turned against them as in a sciencefiction horror film.Many of the diseases of our time obesity, diabetes, manyformsofcancer, autoimmune disorders, allergies are nowunderstood to be plausibly connected to the diminishing diversity of bacteria. Buildings have their own microbiomes, and the diversity of these microbiomes is just as important in buildings as they are in human bodies. The bacteria of buildings continuously enter the body and the bacteria in the body are spread out across buildings along with the bacteria of fellow humans, other animals, insects and plants.Models of health paradoxically produce vulnerabilities toillnessAll these archaeological layers of sick architecture are inherently political. Models of health paradoxically produce vulnerabilities toillness. They privilege and shelter a normalised subject from threatening others. The violent exercise of colonial power, whether external or internal, is inseparable from the architecture of health. The ancient emergency strategy of the cordon sanitaire, used to isolate territories during the centuries of plague epidemics, for example, was turned into an instrument of permanent urban planning in the Belgian Congo to separate the Indigenous city fromthe European city in the name of preventing yellow fever, as suggested in the research of the artist Sammy Baloji. A 400mwide band, the distance it was thought no mosquito could fly, divided Black citizens from white settlers. The mosquito dimensioned the city. But the medical border acted as a mechanism of racialisation. In fact, all borders, whether of a room or a nation, are medical borders reinforced by countless protocols and policing. These borders are typically not a single line but a nesting of lines at multiple scales, each with its own architecture.The construction of the Panama Canal, which was first and foremost the conquest of the mosquito, involved hugescale interventions like clearing forests and draining swamps. Thearchitecture of health is always multiscalar, traversing and definingterritory, nation, ethnicity, race, class and domesticities. Itcreates models of normality, which are also models of exclusion, disadvantage and prejudice.Health is not just physical. Already in ancient Greece, a variety ofmental illnesses were identified and spatialised, as sufferers were forced to remain indoors or roam the outdoors without a permanent address. Eventually specialised buildings offered both isolation and care. Thepreeminent philosopher and physician in the Muslim world IbnSina, also known in the west as Avicenna, worked in the first mental health hospital set up in Baghdad in the 8th century to treat the head sick with calming gardens and fountains, in buildings located in the heart of the city to encourage visitors. His Canon of Medicine considered psychology to be very important and was the most influential medical text in Europe up to the 17th century. TheHospital dels Innocents, founded in Valencia, Spain, in 1410, after observing the Islamic institutions that housed the insane, isconsidered the first psychiatric hospital in the western world. Eventually the whole architecture of mental illness was undone by the antipsychiatry movement in the 1960s, but the experimentation continues today in architectures that allow those on an expanded mental spectrum to be at once sheltered and engaged in city life. Inthe Caritas psychiatric centre in Belgium (AR September 2018), designed by de Vylder Vinck Taillieu with BAVO, neurodivergence isnot treated as an illness and the role of the building is not to isolate but provide a platform.Rather than surfaces that are easy to disinfect, championed by many modernist buildings, probiotic tiles designed by Richard Beckett and Aileen Hoenerloh harbour bacteria. Made of concrete and soil, containing millions of microbes, the textured surfaces encourage the growth of a diverse microbiomeCredit:Richard Beckett and AiIleen HoenerlohDesigned for an ecologist, the shower of the Casa Jardn by Al Borde in Quito, Ecuador, is located in a greenhouse, among the plantsCredit:JAG StudioIn fact, the question of mental health has always been part of architectural discourse. Architects act as if their designs will produce a sense of wellbeing. Each mental condition needs to be countered by architecture. At the turn of the 20th century in Vienna, Camillo Sitte diagnosed the modern city as producing agoraphobia, in the very moment and place the Vienna of Freud the disorder was being actively discussed. Sitte presented his urban design, inspired by the eccentric narrow streets and small piazzas of medieval cities, as a psychological counter. In the late 1940s and 50s, Richard Neutra presented himself as a shrink to his clients, which he understood to be his patients. Likewise, when the concept of stress was identified in the 1960s as the predominant reaction tomodern life, experimental architects such as CoopHimmelblau worked with psychiatrists to produce prototypes of relaxation architectures, as discussed by Victoria Bugge ye. Hans Hollein replaced buildings altogether with an architecture pill providing the desired mental state. In reverse, some conditions such as autism are now seen as inherently spatial, and imply an alternative architecture in its own right. In addition to architectures for an expanded mental spectrum, there is the need to embrace an expanded understanding of the physical spectrum. The diverse abilities of children, older people, those with limb differences, deafness, blindness, and people who arechronically ill call for greater hospitality, opportunity and pleasure from architecture, redefining the very concept of care and transforming the role of buildings in a way that impacts many more than those being treated. Using the language of their time, Aino and Alvar Aalto offered a crucial paradigm shift when they argued that architects should always design for the person in the weakest position. The radicality of thisis to rethink architecture from vulnerability itself.The age of antibiotics and antibiotic architecture threatens our species. The microbiologist Martin Blaser writes about the silent extinction of microbes, arguing that the crisis of the diminishing diversity of the human microbiome is a bigger threat to the species than climate change. So what would a probiotic architecture be? Probably it would be like our gut: more porous, versus the prophylactic attitude of modern architecture. The immune system does not simply keep foreign organisms out; it regulates a dynamic balance between insiders and outsiders. Architecture too could be away of bringing the other in. This might mean experimenting with the idea of rewilding the interior. We used to live intimately with all the bacteria of the soil, the plants and other animals. And we may want to reconnect with even embrace this diversity of bacteria.In the UK, NHS providers produce around 156,000 tonnes of clinical waste every year. This rocketed during the height of the Covid-19 pandemic, with the explosion of single-use plastic PPE (personal protective equipment). The photographs of Natasha Durlachers Postcards from the Pandemic depict discarded masks and gloves, a solemn reminder of the devastating impact of growing ocean and landpollutionCredit:Natasha DurlacherThere is a precedent for a probiotic architecture one that fosterstransspecies communities in some of the work of the ItalianBrazilian architect Lina Bo Bardi. When she designed her Casa de Vidro in So Paulo in 1949, a house suspended in the forest, like a treehouse, she drew every insect, plant and animal living in the site with the same precision that she drew the building. For her they are part of the building. If architecture is all about keeping the bugs out, Bo Bardi embraces a transspecies architecture where insects are not the enemy, but intelligent members of the community, and humans are just temporary guests. She made exhibitions and plays for children about this new understanding of community, imagining spaces in which insects, animals and plants are the real occupants. For Bo Bardi, architecture is architecture only inasmuch as it is dissolved by other species. Even her dramatic demonstrations of geometry and force, like the remarkable MASP, were originally drawn as if being eaten by plants. This is part of a political ethic ofcelebrating and learning from other species.Architecture today needs to be dramatically reconfigured onhealth grounds just as modern architecture polemically reconfigured the 19thcentury architectures that preceded it. Humancentred design sounds good, but it is terrible for humans, aswell as other species and the planet. The first form of life was bacteria, four billion years ago, while the human is a very recent arrival and might already be on the way out. Bacteria are what madeplants, trees and eventually humans possible. The human isnot just one thing but an endlessly complex, everchanging transspecies collaboration: the human is a bag of bacteria. But bacteria are usually treated as an invisible enemy that needs to be exterminated. Instead, bacteria should be at the centre of design. We are nothing without all these foreigners. We live in them more than they live in us.This is the Keynote essay from AR April 2025: Health. Buy your copy at the ARs online shop, or read more from the issue here