An entire town filled with nuclear laboratories, built from scratch in the remote mountains of New Mexico, with every single person involved sworn to secrecy?

It is not just the plot of "Oppenheimer," but also the story of how Christopher Nolan's Oscar-nominated movie about the invention of the atomic bomb was made.

"This is the most I've ever spoken about it," said David Manzanares, field producer for Ghost Ranch, as he took AFP on a recent tour of the location for the movie's Los Alamos scenes.

"It definitely took on the air of secrecy," he recalled.

A few miles from the nearest paved road, through gates marked "RESTRICTED AREA," many of the wooden homes, offices, security checkpoints and even a chapel built for the film remain standing.

The buildings line a dusty street that is bookended by stunning purple-hued mountains.

The real Los Alamos -- an hour's drive away -- is now a modern town that remains home to a giant, top-secret government lab charged with safeguarding the US nuclear stockpile. Its historic buildings were used for several interior scenes.

But Nolan selected this far corner of the southwestern US state to double as the town for exterior scenes, constructing a 1940s-era replica of its main street.

The British filmmaker famously insists on using authentic, practical sets to inspire his actors.

The movie's atomic bomb test was shot with minimal computer effects, and real Los Alamos scientists were hired as extras.

This meant the replica of the town had to be built at full-scale, offering Nolan the possibility of filming from every angle at a moment's notice.

But until a month after the film premiered last July, Manzanares and his Ghost Ranch team were not even allowed to acknowledge that the movie had been shot there.

"There was no conversation, there was no posting" allowed, he said.

"That's just the way business is conducted on a Christopher Nolan shoot."

- Mesas -

 

In mid-October 2021, Manzanares was contacted by a friend who works as a location manager for movies, asking if he knew of any pristine sites with wide, sweeping vistas.

The friend could not say what the project was, but shared that it was set in 1940s New Mexico -- enough for Manzanares to hazard a guess, given the buzz already surrounding Nolan's next big film.

Ghost Ranch fit the bill, and the following month, Nolan himself came to check it out.

"He loved it right off the bat," recalled Manzanares.

Nolan gave his blessing, before adding a complication: "Oh, by the way, we need a double of it."

The movie first needed to shoot a scene of Cillian Murphy's titular scientist showing a US army general (Matt Damon) an empty, proposed site for the Manhattan Project's new base.

The following day, they would need to get the cameras rolling on the Los Alamos town set itself.

Having found two sufficiently similar-looking "mesas" -- the elevated rock shelves that make up northern New Mexico's distinctive mountains -- the production set to work.

Crews worked through multiple blizzards that winter to get the set ready in time for eight packed days of shooting, with the A-list cast hunkered down at a hotel down the road.

The secrecy applied to "everyone, even the actors," recalled Manzanares.

"They would get pages, they'd go to their hotel room and read, but they couldn't take the script out."

- Rattlesnakes -

 

The secrecy surrounding "Oppenheimer" was not entirely unusual for a film of its scale and fame.

Media outlets are hungry for any on-set photos, production gossip or script fragments, any of which can spoil a major movie before its premiere.

Once the Los Alamos scenes were complete, the fake town's "laboratories" were removed, as were telephone poles that would soon have blown down in gusty winds.

But producers agreed to leave around a dozen wooden structures standing -- the first time a movie production filmed at Ghost Ranch has been allowed to do so.

That meant the set needed to remain secret for more than a year after filming wrapped.

The site will eventually be used for other movies, such as Westerns.

But before then, from next month, the ranch owners will start offering an "Oppenheimer Tour."

They hope to capitalize if -- as expected -- the movie wins multiple Oscars, including best picture, on March 10.

Employees are currently working to prepare the remote site, which was left to the elements for months.

"We went up there, we found rattlesnakes and black widows," said Ghost Ranch tours manager Julia Haywood.

"It is perfectly safe now," she added.