Square-jawed superhero Steve Rogers lays strangely immobile in the bowels of an enormous “suborbital bomber” — a contraption that looks like Howard Hughes’ legendary Spruce Goose if it were pimped out for Darth Vader. His eyes closed, the hero might be lost in deep contemplation or possibly praying for help to foil an evil plot, in this case the impending launch of a missile targeted at a major American city.

ut from a certain vantage point, his face pressed against the glass encasing the weapon, it sure looks as though Captain America’s snoozing. Even if Chris Evans, who plays the weakling soldier wannabe turned strapping superhero in the new film “Captain America: The First Avenger,” were catching a few winks, it would be tough to blame him. The actor, 30, had to bulk up at the gym to better embody Rogers, who becomes a hulking good guy determined to fight for classic American ideals.

Specifically, Rogers is tasked with thwarting the nefarious designs of the villainous Red Skull(Hugo Weaving) in the World War II-era comic book adaptation, which opens in theaters July 22. In addition to the physical demands of the role, though, Evans has had to spend time wrestling with Rogers’ inner demons.

“He’s given this amazing blessing, all of the ability that he has always wanted,” said Evans on the sidelines of a frigid soundstage at Pinewood Studios outside of London late last year. “That can easily corrupt. If you give anyone this power, it is easy to become a bully and let human emotion take over.”

That notion — essentially that with great power comes great responsibility — is, of course, central to the ethos of more than one star character from the Marvel Comics universe, so it’s perhaps not surprising to find that same message at the core of “Captain America.”

What is perhaps more notable is the movie’s retro-futuristic aesthetic, which production designerRick Heinrichs said is unique in its representation of slick and oversized World War II-era cars, tanks and aircraft; the sets and props combine elegant prewar industrial styles with the organic plantlike visions of the 20th century Catalan architect Antoni Gaudí, who is famous for Barcelona’s Sagrada Familia.

“We’re not doing a historic war movie but a stylized and exaggerated war movie,” Heinrichs said. “It is the future as seen from the past.”

The approach extends too to Rogers’ costume — which includes a distressed leather coat that he wears over his familiar red, white and blue garb.  Speaking with Hero Complex months later, director Joe Johnston (“The Rocketeer”) said he used “Raiders of the Lost Ark” as a template for developing the story.