It’s easy to lose yourself in Walden 7. It’s not just the winding, vertical labyrinth of walkways that confound visitors but also the story behind them that overwhelms. A grand social-housing experiment built on utopian ideals, new urban planning concepts and just a touch of science fiction, it stands as a monument to a time of change in Catalonia. Attitudes were softening, old ideas were being challenged and free thinking embraced in the twilight years of an ageing dictatorship.

To dream it all up, architect Ricardo Bofill removed himself from the distractions and influences of the urban domain and took to the Algerian desert in the early 1970s. Accompanying him were a team of sociologists, poets, philosophers and mathematicians all aiming to flesh out a new vision of the modern housing estate. Each put their own distinct stamp on the result: a building that combines behavioural psychology theories with intricate cubist design and has been peppered with whimsical artistic motifs that are still visible today. Bofill would call the project his City in Space – a hollowed-out, 16-storey complex of 446 residences and street-level shops designed to be a self-sufficient city within a city.

However, officially it’s Walden 7 – a name derived from 1948 science fiction novel Walden Two. In the story, author BF Skinner explored how environmental variables could be tweaked to create a utopian community – a grand aim the creators of this building attempted to replicate.

An unlikely setting for utopia, Walden 7 was built alongside a disused cement factory in the industrial town of Sant Just Desvern on the outskirts of Barcelona. Upon completion in 1974 it became an instant attraction for a new breed of the Catalonian middle class. Drawn here by the promise of living in a community of like-minded non-conformists, many were eager to participate in Bofill’s ambitious social experiment.

Stories abound of the creative energy that initially filled the space, spurred by the artists, poets and iconoclasts that made up the first wave of residents. Lavish parties were held on the rooftop, community decisions were taken via regular assemblies and among the 1,000-strong group of residents there was a tangible collective will to make it all work.

Nearly 40 years later, a more diverse generation of residents populates the building. As Walden 7 never had a central owner, the residents themselves are responsible for how the building is run. Assemblies are still held and the management team is chosen by popular vote. This democratic structure has been maintained since the outset and while the euphoria of the early days has dissipated, the strong sense of community has endured.

Wandering the maze of exterior passageways and zigzagging up the Escher-like stairs, relics of the building’s early bohemian days leap out: a sign in the corner of the rooftop terrace marks the location of a nudist section; verses of poetry line the walls of the subterranean car park; and the network of corridors are labelled with names such as Frank Kafka, Albert Einstein and Jesse Owens. There’s even a modest communal library that sits alongside the main entrance.

While rooftop parties are a thing of the past, neighbours still band together for the summertime cinema held in one of the seven interior courtyards, play ping pong at the communal tables (but not after 22.00, thank you) and proudly donate 0.7 per cent of the building’s annual budget to international charities.

In a town of just 16,000, an eccentric building that houses more than 1,000 residents has a strong presence: everyone from the mayor to the police chief and, rumour has it, the local madam have snapped up space. Meanwhile, a wave of young architects has begun moving in, keen to form part of Walden 7’s ever-evolving story.

Spiralling around in both horizontal and vertical patterns, the apartments comprise 30 sq m modules. A studio is made up of just one module but standard single- storey and duplex apartments range from two to four. The design of the concrete structure has allowed for possible interconnectivity between apartments on the same floor and as a result the number of residences has been altered, making it hard to know the exact number today.

A terracotta-coloured façade is a nod to the Algerian desert, while a cooling turquoise blue in the interior takes its cue from North African medina, prompting many residents to refer to the building as “The Kasbah”. A mixture of garden furniture and pot plants scattered throughout are reminiscent of a traditional Spanish village. In a break from the region’s love affair with modernism, the building prefers jagged structural lines that resemble a distorted Rubik’s cube.

A much grander complex of four buildings was conceived but a regional banking crisis left Walden 7 standing alone, surrounded by green space and the neighbouring cement factory that Bofill converted into his studio and home. mWhether this miniature city has lived up to its utopian vision depends on who you talk to. In no doubt is the sense of pride residents have – they praise the considered use of light and space, the acoustic design and the neighbourly charm.

The idea that our environment can influence how we behave may have once been the stuff of science fiction but buildings such as Walden 7 have grounded it in reality. The surviving community may be more complex than any utopian ideals but their faithful subscription to this vision continues to hold them together.

The residents 1

Miquel and Lola Abella

Arriving at Walden 7 in 1980, Miquel and Lola Abella moved to a bigger three-module home 10 years later. The first tenant was Joan Margarit i Consarnau – a poet and architect who helped design the structure and elucidate the building’s utopian vision.

The couple live here with their 25-year-old daughter Magda, who quietly admits that she’s not quite ready to move out of the beloved building. The corner apartment’s five concave balconies provide sweeping views of Bofill’s Taller de Arquitectura below.

Miquel has since retired and spends much of his time at home listening to his extensive collection of blues records and compiling musical databases for various organisations and associations.

“People really get to know each other here,” says the chirpy retiree. “I’ve met the majority of my closest lifelong friends right here in the building.”

The residents 2

Luis Calau and Julia Morgado

Forming part of the wave of younger residents buying into Bofill’s vision, this Portuguese couple moved into their apartment on Pablo Neruda Street in 2006. Motivated by the promise of a better life for their two young daughters, as architects they were already aware of the building’s philosophy and history.

“The previous owner had choked up the space, subdividing rooms and removing the interior’s split levels,” says Julia, who was working in Bofill’s studio at the time. “We got the original plans and restored it to its initial state.” She adds, “This building is like a small village, providing the elements of freedom and tranquility that our daughters just wouldn’t have in the big city.”

The residents 3

Araceli and Gábor Somssich

This couple moved into Poincare Passage 15 years ago after the birth of their daughter. Today they enjoy a four-module apartment with a prime exterior location on the 12th floor. “We wanted to live closer to work and have more outdoor space for our daughter,” says Araceli, who works at a nearby university. Her Hungarian-Belgian husband can easily walk to his desk, which is conveniently located inside Bofill’s neighbouring studio.

“Even though we live in a high-rise, there is a sense of proximity to the outdoors,” she says as she gazes out of a window with views of Montserrat Mountain. “I like the diversity of the people that live here. It’s a balance that has endured for years.”