At 90, architect Vann Molyvann no longer cuts the figure that a man of his stature deserves. In an early scene in The Man Who Built Cambodia, a documentary premiering tonight at the French Institute, he shuffles toward a shrine, wearing not his characteristic blue-collared shirt and suspenders, but short sleeves and a pair of track pants. He folds his hands into a sampeah.

Yet he is a formidable interviewee, says director Christopher Rompré. “He doesn’t ever go where you think he’s going to go, and he won’t repeat something,” he says.

The 37-minute film, the first to focus on Molyvann’s life and legacy, brings a man long absent from the public sphere into an intimate conversation with his audience. Rompré and producer Haig Balian began the project nearly three years ago with a grant from the Asia Foundation, conducting lengthy interviews with the architect in his home – first in Phnom Penh, and then in Siem Reap, where he moved in 2014.

When it comes to speaking about the philosophy of his architecture, Molyvann is more comfortable in French. He lived in Switzerland for two decades, and studied in Paris, where he encountered modern architecture, and took especially to the work of Le Corbusier, whose influence is evident in his designs around Phnom Penh.

“Why did I choose Le Corbusier?” he asks on-screen. “Because Le Corbusier created his unités ‘d’habitation on stilts,” recalling ancient Khmer design. The film contrasts Molyvann’s brand of “ecological architecture” with the construction frenzy of the past decade, and engages with an exchange between the past and present that at times seems tenuous in Cambodia.

Take, for example, Molyvann’s return from France to an independent Cambodia. It was the mid-1950s, and the country was on the cusp of a popular renaissance.

“The architects of Angkor . . . for Cambodians are like gods,” Molyvann says early in the film. But upon his arrival, he explains, “I couldn’t find work; nobody wanted me. Because nobody knew what the job of an ‘architect’ was.”

That soon changed, as then-head of state Prince Sihanouk embarked on a productive partnership with Molyvann, who designed or oversaw most of the public projects during the Sangkum era, including Independence Monument, the National Theatre, Chaktomuk Theatre and the Olympic Stadium.

The Man Who Built Cambodia features plenty of drone footage of the landmarks that remain.

“For this project, it made a huge difference, because large-scale buildings are hard to appreciate on the ground level,” Rompré says. “[It] gives you a sense of his work – and the grandeur.”

The film swoops time and again over the stadium, which it highlights as the epitome of Molyvann’s signature style.

In person, Rompré gets caught up in describing the intricacies of this multi-function, ecological design: the natural illumination, the self-cooling mechanism, the protective overhang. But on-screen, what is arresting about the structure is its human element: people move over every surface.

In the immediate background, identical green-wrapped towers rise, casting a shadow and obscuring the stadium from the rest of Phnom Penh, which Molyvann once re-imagined in its entirety when head of urban planning under Sihanouk.

“One of the things that is quite obvious living in Phnom Penh is just the change that is happening here,” Balian says. It was this notion, in addition to Molyvann’s character, that inspired the pair to make the film.

Molyvann came back to Cambodia in 1991, the same year as Sihanouk, but the script was different from his first return. He headed up the restoration of Angkor Wat, but was sacked in 2001, and he was never able to achieve his vision for the capital. Even his physical legacy faded. The National Theatre burned; his Council of Ministers building was replaced with a Chinese design; others have been rendered unrecognisable.

And so he faded from public view. “You should know first that Molyvann is not a politician, he is a technician,” Khoun Khun-Neay, his chief of staff, says in the film, laughing. It’s in the later interviews with Molyvann that this gap is most evident: in the defeatism of a man so closely associated with Cambodia’s “golden age”, cloistered in Siem Reap, far from his life’s work. When asked on-screen how he feels about what’s happened, he responds immediately, with one word: “Powerless.”

It’s a point of rare and raw emotion. “There’s a moment where he tears up a little bit,” Rompré says. “But because of how stolid he is, just that little hint of his eye getting slightly watery was a huge impact. He’s not an emotional man.”

Rompré and Balian originally wanted to premiere the film in one of Molyvann’s remaining spaces.

“One of the reasons that it has taken so long to get this film shown in Cambodia” – it was completed in 2015 – “is that we really wanted to show the film at Chaktomuk Theatre,” Balian says. But in order to do so, they needed approval from the Ministry of Culture, which wanted them to edit the title and the final scene in which Molyvann calls for an intellectual “rebellion” in Cambodia among the youth.

It’s a point that the architect clarifies, and stands by. Molyvann wants his legacy to outlast his buildings, just as the filmmaking team want The Man Who Built Cambodia to take hold with a large audience.

For now, it seems like it will: there are far more people clamouring for tickets than the French Institute’s small theatre will hold. For Rompré and Balian, the hype for their own work – as well as its scale – has come as a bit of a surprise. The film could go down as the definitive portrait of Molyvann.

“At first, we thought we were just going to do a weekend project about an architect,” Rompré says with a laugh.

In their last visit with Molyvann in Siem Reap, the pair brought with them the film poster, which casts Molyvann in silhouette beneath Olympic Stadium’s overhang, looking out onto the field – a man overshadowed by the scale of his own work.

“He loved it,” Haig says.

The Man Who Built Cambodia premieres tonight at 7pm at the French Institute, #218 Street 184, with a second screening on Saturday at 7pm. Tickets ($2) will be available at the door at 6pm both evenings. For those unable to acquire tickets, the film will stream for free at www.themanwhobuiltcambodia.com from Friday night through Sunday.