On the aptly named Avenida Industria on the western outskirts of Barcelona sits a craggy concrete relic of Catalonia’s industrial past. But this ruin, peeking out from behind lush foliage, quickly reveals itself to be a study in reinvention. Nestled deep within groups of concrete silos and the cavernous space of a former cement factory is La Fabrica. It’s home to renowned post-modernist architect Ricardo Bofill’s studio and his extensive archive, as well as several apartments used by friends and family and the architect’s own home.

On the morning that monocle visits, the Ricardo Bofill Taller de Arquitectura team is gathering for a meeting under the soaring ceilings of a room they call the Cathedral. This immense concrete space, a former factory hall, is the heart of the architecture firm; a long wooden conference table, project mock-ups and a grand piano (untuned) line the space. The interiors remain unapologetically industrial, with Bofill even retaining some of the cement factory’s old machinery as a reminder of Catalonia’s heritage. “The beginning of the 20th century was a successful time for my country’s industrialisation,” he says. “So keeping this type of building alive is important for our memory – the memory of young people.”

Bofill, now 79, discovered the place by chance while walking around the area in the early 1970s and was instantly intrigued. “I was fascinated by the possibilities I saw in these ruins. I had to carve into the cement and I felt like a sculptor in front of a material in its primitive state. It was very exciting.”

But it took a lot of work and a year and a half of dust and detonations. “It’s now hard to imagine but when we arrived in 1973 there was nothing here but the factory,” says Serena Vergano, Bofill’s publications manager.

Stepping outside into a tiled courtyard that separates the Cathedral from the silos, Vergano explains that much of the factory’s original structure was blown up to make room for the gardens and to hollow out the silos, which were full of concrete. These circular spaces have been repurposed into several floors of snug whitewashed offices, illuminated by slender gothic-style windows.

Today some 60 architects and designers work here, handling international projects such as a university campus in Morocco, housing in Tbilisi and a large masterplan for an eco-friendly neighbourhood in Beijing. Bofill now has some 1,000 designs to his name and has built more than 300 projects. Despite his age, he isn’t showing any signs of slowing down.

To keep things fresh and ideas flowing, teams are mixed up for each new project and architects are encouraged to move around the various parts of the building throughout the day, whether brainstorming in the olive grove, running a workshop in the Cathedral or having a coffee break on the spiralling stairs in the silos. Unlike in most offices there are few private rooms – and that’s on purpose. “What’s really important is that there are no cubicles, and meetings take place in the centre of the office where everyone can hear, participate and know what’s happening,” says senior architect Gabor Somssich, as he stacks architectural plans for Beijing on the desk of his oval office. “It’s never isolating.”

The gardens here are just as important as the architecture. Fragrant eucalyptus, palm and olive trees are carefully planted, while ivy crawls abundantly up the exposed concrete walls. A picnic table provides an inviting spot for architects to take their lunch break.

Despite its tumble-down appearance, Bofill has carefully shaped La Fabrica, adding concrete parking bays for staff, a 3D printing studio in the silos and post-modernist concrete flourishes to the exteriors. But there are few concessions to modern office design here: chairs are elegant bentwood Thonets, heating the cavernous space of the Cathedral is tricky and there is no canteen to speak of. A few of the architects live nearby and pop home for lunch, while others take turns sharing a communal table tucked into a basement room or head outside to the sprawling gardens. There is also little space for taking some time out or having an informal meeting. Somssich concedes that a lounge or a social space would be a welcome addition but – as with everything here – that’s up to the architect in chief. “This is Bofill’s oasis. It’s his story, he manages it.”

La Fabrica’s old bones mean that it requires constant maintenance. “The cement and the iron: they don’t work together so well. We are always fixing, fixing, fixing,” says Vergano. “But it’s worth it.” There’s also the possibility of expanding to fit in more staff. As we cross the echoing Cathedral and emerge into another garden planted with palms and slender bamboo, she points to a raw-concrete silo with a gaping hole in its side, ready to be transformed into more offices.

So although the building is ostensibly “finished”, it retains the potential of a perpetual work in progress. “The building is really the synthesis of who we are, the way we work,” says Bofill’s son Pablo, now CEO of the company (Bofill’s other son, Ricardo, is president). He lights a cigarette – unusually, smoking is allowed inside – and leans on a wooden table designed by his father. “The fact that it’s a building that looks like it’s always under construction helps to show that our architecture is not something defined. It has to be under constant evolution.”