As Barcelona begins to sleep, it doesn’t shut down; it transforms. As shop shutters fall and terraces clear their last chairs, another city begins to rise on the sidewalks, parallel and invisible in daylight. A city that doesn’t appear in urban plans or institutional speeches but exists with an almost physical intensity.
The Ephemeral City: Cardboard, Plastic, and Ingenuity
This is a city made of cardboard, plastic, wood, vertical mattresses, abandoned furniture, and blankets folded with surgical precision. In the brightest avenues, beneath luxury shop windows and modernist facades, while monumental buildings cast long shadows on the pavement, dozens of people begin to build their homes. Ephemeral, movable, silent homes. Homes that are erected every night and dismantled at dawn, as if the city were a theater stage where each actor knows by heart the exact time they have to set up their scenery before the sun rises. The nocturnal Barcelona, the one almost no one sees, is full of ingenious and involuntary architects.
Some build walls with packing boxes, composing facades of repeated geometries in front of emblematic buildings. Others use carts, blankets, and sheets to create small interiors in the middle of a playground. There are those who take advantage of the warmth of a shop window’s LED light to turn it into their bedroom lantern, and those who, with the meticulousness of a carpenter, reconstruct the same cardboard house every night, layer by layer, as a ritual of survival.
According to the Arrels foundation, more than 1,300 people sleep on the streets of Barcelona every night. But that number doesn’t explain what happens between 10 PM and 6 AM. It doesn’t tell us that the city becomes, for a few hours, a collective workshop where each person designs their own refuge according to what they find, what they have managed to save, or what the night allows them.
Here, in this other plane of the city, architecture is not a profession: it’s an urgency. And its raw material is not bricks or concrete, but remnants: what the city discards, others turn into a home. This report is a journey through that “other city” that emerges at nightfall.
The Children’s Playhouse That Becomes a Bedroom
In Passeig de Sant Joan, the wooden playhouses of a playground acquire an unexpected use. Under the yellow light of the streetlights, a play structure appears closed with a white sheet placed as an improvised curtain. Beneath it, a duvet peeks out, serving as a mattress.
The small roof, designed to protect children from the rain, becomes a small habitable cover, reinforced with cardboard to block the light. There is no improvisation here, but a surprising reinterpretation of urban furniture: a micro-dwelling, parasitic, as domestic in its composition as it is forceful in its architectural resolution. Wood, textile, and cardboard coexist with the playful aesthetics of the park, creating a contrast that, in a design magazine, could be described as a “stylistic hybrid.”
Bench + Plastic: Extreme Minimalism
A few meters below, a public bench transforms into an ultra-minimalist refuge. A large black plastic sheet, spread like a skin, covers it completely. There is no structure, no walls: only the bench as a foundation and the plastic as an enclosure. Beside it, a water bottle, a purple bag, small everyday objects. This is the most essential architecture of the nocturnal city: one where materials are not even enough to erect a module. A single-piece textile “pavilion,” built with the same logic as a mountain shelter, but in the middle of the Eixample.
The Designer Shop Window That Houses a Cardboard Shelter
On Diagonal, in front of the illuminated shop window of Pilma, one of the temples of contemporary furniture, two large cardboard sheets form an improvised wall. The scene looks like something out of an art installation: brown cardboard versus designer lighting, or improvised shelter versus perfectly ordered furniture behind the glass. The composition is almost cinematic. The person sleeping there uses the base of the shop window as if it were the porch of a modern house. The interior light becomes a lantern. The glass, a protective wall. And the cardboard, an emergency facade.
The Barricade of Discarded Items
In another section of Diagonal, the furniture collection day generates an extraordinary phenomenon: a man has erected an urban barricade around a tree. A vertical mattress acts as a soft, yet surprisingly solid wall. In front of it, an accumulation of discarded furniture (chairs, boards, small cabinets) forms a kind of domestic moat. The ensemble is a kind of ephemeral wall, built with the speed of someone who knows that dawn will bring municipal officials and garbage trucks. It is an architecture of opportunity: it arises only when the city “delivers” material. That night, the tree was the center of a small defensive palace.
The Urban Installation of the Sign Man
On another corner of Diagonal, a cart covered with blankets, plastics, and cardboard appears decorated with handwritten signs and an improvised French flag. Under the cart, perfectly aligned bottles create a miniature “storage.” It’s not just a refuge: it’s a narrative, an identity, a message. This person, whom some say is a famous Catalan writer who lost his mind, has created a work that combines architecture, communication, and protest. It is one of the most complex examples in the entire city: an expressive micro-architecture, where each layer of blankets, cardboard, and banners functions as a stratum of meaning.
Porticoed Areas as Habitable Capsules
In several corporate buildings, the nocturnal porch functions as a capsule dwelling. There are no walls, only a roof: a rolled-up blanket on the floor, a cart full of belongings, and the modern geometry of the building as an enclosure. It is the architecture of parasitism: where the formal city offers a gap, someone turns it into a bedroom.
The Blue Mattress Architecture: Improvised Ergonomics
In front of a Veritas store, another refuge surprises with its almost domestic composition: a blue bed foam, folded to simulate a sofa. Below, cardboard boxes as foundations. To one side, bags, bottles, small objects. There is an attempt to compose a living room, to replicate an interior within the exterior. A search for comfort that recalls the bohemian interiors photographed in decoration magazines… with the difference that this time the ceiling is the sky.
“Sadaka”: The Red Shop Window and the Covered Cart
On Passeig de Gràcia, next to Adidas’ red shop window, a cart covered with cardboard has the word “Sadaka” written on it, which means voluntary charity in Arabic. The red LED light bathes the entire scene with a vibrant contrast: premium advertising illuminating a humble refuge, almost turned into a small altar.
The City Walled with Boxes: Comedia, Barcelona Stock Exchange, Zara, or Dr. Martens
In the final stretch of Passeig de Gràcia, scenes appear that look like models made by architecture students. Dozens, hundreds of boxes piled in front of emblematic facades of the old Comedia Cinema, the Barcelona Stock Exchange, or the boutiques of Zara, Salsa Jeans, or Dr. Martens. The boxes do not form homes: they form walls, soft borders that redraw the ground floor of the buildings. Their function is double, as they protect them from the wind but also define the territory. The latter is necessary in a city like Barcelona, where every square meter counts, even in the homeless environment.
These walls turn the golden mile into a corridor of rectangular modules that, under the night light, look like contemporary installations.
The Night Architect of Cardboard (The Story of the Man Who Builds and Dismantles His House Every Day)
On Calle Casp, one of the side streets of Passeig de Gràcia, a man builds a small cardboard house every night with surprising precision. “And you do this every night?” “Every night.” “How long have you been coming here every night?” “I’ve been here for almost six months.” “Is all this made of cardboard?” “Only cardboard. There’s nothing else.” “And when do you have to dismantle it?” “First thing in the morning…” (before commercial activity begins). He creates his home daily, like a ritual. It is ephemeral architecture by obligation, a house with an expiration date every dawn. He works in silence, piece by piece, like a cardboard artisan. And the next day, he starts again.
His figure embodies the entire idea of homeless architecture: building knowing that everything will be dismantled. Homeless architecture doesn’t seek to move you; it seeks to show you how the city truly transforms. It’s not a story of pity, but of creativity, resilience, adaptation, and design from precariousness. When Barcelona sleeps, another city is born, made of materials that no one claims but which, in the hands of those who need them, become walls, roofs, rooms, depots, barricades, or places of intimacy. A city that disappears at dawn, but that reappears every night. A city that exists because the other one doesn’t know (or doesn’t want) to house everyone.
Source: https://www.idealista.com/news/inmobiliario/vivienda/2026/02/16/883673-arquitectura-de-carton-la-barcelona-que-se-construye-cuando-se-apagan-las-luces
