NEW YORK — During rehearsals for “Hairspray,” Jerry Mitchell turned to Jack O’Brien to say, “He may be the most famous person we know!”O’Brien agreed. The choreographer was talking about the show’s architect-turned-set designer, David Rockwell. “In our theater crowd, we don’t run with that pack,” O’Brien says. “And there is David, one of the most iconoclastic architects of his generation, and he is backstage playing with us!” Rockwell is backstage with the boys again, at work on new tuner “Dirty Rotten Scoundrels,” which opens next month at San Diego’s Old Globe. Before Rockwell brought his architecture to the theater, he was bringing the theater to his architecture. “Many of Rockwell Group’s projects, particularly their restaurants, are often described in terms of theater, or sometimes film,” wrote Columbia U’s Arnold Aronson. The staircases at Union Square’s W Hotel and Times Square’s Ruby Foo’s restaurant, for example, have inspired references to Norma Desmond and Auntie Mamie. Today, the 140-member team at the Rockwell Group is as likely to design sets as the theaters that house them. Having already built Hollywood’s Kodak Theater and the Cirque du Soleil venue at Orlando’s Walt Disney World, the 120-member team starts work on the Venetian Hotel’s new home for the 90-minute “Phantom of the Opera” in Las Vegas. Skedded to open in fall 2006, the venue is inspired by 19th-century theaters. Back in Gotham, the Film Society at Lincoln Center is expanding its domain to quarters under the fabled plaza, which will include two venues by Rockwell. Other showbiz-related projects include Detroit’s new Motown Center and the Ertegun Hall of Fame, opening in October in the new Jazz at Lincoln Center complex. “We wanted the space to be the inner sanctum of our hall,” says Wynton Marsalis, JALC’s artistic director. “We needed the feeling of a chapel, but also a park.” Rockwell obliged by making a series of huge doors the centerpiece of his design. In addition to staircases, doors are a big deal in Rockwell world. As he explains, “Entrances are the major overlap of theater and architecture.” The Film Society had little space for its new lobby under the Lincoln Center plaza. “It couldn’t be a dark hole in the ground,” says Joanne Koch, org’s exec VP. And due to limited footage, it needed to serve more than one function. Thus, “Rockwell has turned the entrance into a very exciting amphitheater,” which also will serve as a lecture hall. “Problem-solving through fantastic design is a Rockwell hallmark,” says Jordan Roth, the producer whose 2000 revival of “The Rocky Horror Show” gave the architect his first shot at Broadway problem-solving. Director Christopher Ashley needed to move the action from the movie theater to the castle with breakneck speed. “But how do we get rid of the movie seats?” he wondered. Rockwell came back the next day with the solution — “Through the floor!” — which gave the tuner its first showstopper. Before the two men started work on “Rocky Horror,” Ashley had seen Rockwell’s “Seussical” designs (veteran, Eugene Lee eventually won the assignment) and had been wowed. “It was all inflatable,” Ashley recalls. “The design was simple and high-concept simultaneously.” People have a way of using contradictions to describe Rockwell’s work. “It is simultaneously camp and beautiful,” says Scott Rudin, whose upcoming marionette epic “Teen America” marks Rockwell’s first film project. The design conflict that Ashley and Rudin refer to is what Rockwell calls “extravagant minimalism.” Take, for instance, the miles of ordinary rubber tubing that he turned into a luxuriant red curtain in “Hairspray.” O’Brien remembers long talks with the creative team about Necco Wafers. “We were discussing the vocabulary of ‘Hairspray,’ and David took us literally. You want to eat aspects of that set.” For their new collaboration, “Dirty Rotten Scoundrels,” set on the Riviera, Rockwell has chosen to bejewel everything, according to O’Brien, “including the palm trees!” For the set of “All Shook Up,” which follows “Scoundrels” to Broadway in the spring, a small Midwestern town will be constructed from found objects — tires, license plates, gum wrappers.