“Superman” production designer Beth Mickle spent six months designing Superman’s home, the Fortress of Solitude, and a further 16 weeks building the set.

James Gunn wanted a practical set for the place the superhero retreats to, and not something created with CG or virtual production. Mickle, who worked with Gunn on “Guardians of the Galaxy 3,” calls the Fortress one of her most challenging set builds. “We felt so much pressure to pay homage to the original and to keep audiences happy,” she told Variety. In the Richard Donner films, an ice crystal was thrown into the ground, and a crystalline structure would grow out of the ground.

While honoring what had come before, Mickle also wanted to inject something fresh into imagining what the set would look like.

Gunn’s film picks up in a world that is familiar as Superman (David Corenswet) and several other heroes fly around as the Justice Gang, an early prototype of what’s soon to become the Justice League. The gang is made up of Green Lantern Corps member Guy Gardner (Nathan Fillion), the high-flying Hawkgirl (Isabela Merced), shape-shifting Metamorpho (Anthony Carrigan) and the super-smart Mister Terrific (Edi Gathegi). Together, Superman must face off against his ultimate nemesis, the evil megalomaniac Lex Luthor (Nicholas Hoult), while also balancing his relationship with ace Daily Planet reporter Lois Lane (Rachel Brosnahan).

The film opens with Superman beaten down, lying in the snow. But he’s too weak to move, and so calls on Krypto the dog to save him. Once Krypto realizes Superman needs help, he drags him across the ice “home.” As they get closer, a Fortress of Solitude emerges from beneath the ground.

It’s an awe-inspiring and familiar sight, but Mickle’s update to the Fortress is apparent.

The Fortress exteriors were shot in Norway’s Svalbard, an archipelago between Norway and the North Pole, whose icy terrain was the perfect setting for the frosty fort. Mickle admits, “Building it was a massive challenge. We built 242 giant crystals, they’re all real.” The only interaction with CG, she says, was to create the movement of the Fortress as it rises from below the ice.

The crystals were made from resin.“ All the resin that existed on the Eastern seaboard in 2023, we bought it all,” says Mickle, “It was cheaper than a CGI set.”

Inside Superman’s secret base are the robots, who are referred to by their respective numbers. They heal him by exposing him to the solar rays.

The “computer dashboard” and every crystal behind it, along with the floor, were also physical builds.

Mickle recalled what it was like when Corenswet saw the set for the first time. “Nobody was in there because they were going to be shooting an exterior. I turned around and saw David walking up the steps in his long red cape.” She added, “He came over, was so gracious and complimented the set.”

As for the possibility of a sequel, and whether Gunn has discussed ideas for more, Mickle’s lips remain sealed. “I’m not allowed to speak about that,” she laughed.