When the New World Symphony moved out of its longtime home at Miami Beach’s Lincoln Theatre last year, some fans despaired over what would become of the splendid Art Deco building, one of the undisputed architectural gems of South Beach if not all of Florida.

It turns out they had nothing to worry about.

Confronted with the daunting question of what to do with an obsolete but historic movie house, developer Cliff Stein, whose investment group paid $21.5 million for the building to turn it into a retail center, decided on a gutsy answer:

You meticulously put back the glamorously vaulted Deco auditorium that had been stripped in previous conversions — including a screen for moving pictures. You restore the terrazzo-floored, keystone-walled lobby to within an inch of the 1936 original. You bring back its streamlined exterior to the authentic, metal-edged muscularity of the day it opened.

And you modernize the shell by peeling open the back of the theater to expose its interior to the passing multitudes.

Then you enjoy the spoils as European retailers fall over themselves to pay top-dollar rent to sell their goods inside.

“I saw what it could be, but not everyone did,’’ said Stein, a lawyer and veteran of numerous real-estate projects who readily concedes he had never tackled anything with the scale and complexity of the Lincoln Theatre renovation. “But it’s all come together from the investment standpoint. And when it’s done, it’s going to be a masterpiece.’’

The risky renovation, now nearing completion, has already proved a financial home run for Stein and his investors. It may also set a new high standard for the reuse of historic buildings on the mall and the adjacent Art Deco historic district, where the sometimes clashing needs of commerce and architectural integrity can lead to heated battles and imperfect compromises.

Not this time, delighted city officials say.

“The buzz on this is pretty amazing,’’ said Miami Beach preservation officer Thomas Mooney. “This project has really pushed the envelope in terms of conversion.’’

The $11 million transformation, designed by prominent Miami architect Allan Shulman, is already evident on the corner of Lincoln Road and Pennsylvania Avenue. The streamlined, overhanging marquee is newly covered by stainless-steel banding, a precise reproduction of the original, which had been stripped off decades ago for donation to the nation’s World War II effort. The building’s curving exterior, crowned by a dazzling Deco floral relief, is again a sparkling white after years in mustard yellow.

Along the pedestrian mall, ziggurat-shaped windows that had been blocked off for years have been reopened and reglazed over the entrances to street-level retail spaces that housed a pharmacy and cafeteria in the theater’s glory days. Those doors will again admit customers to new shops and a restaurant.

The most dramatic change comes at the alley at the rear of the building, the theater’s once-blank back wall, which now consists almost entirely of glass two stories in height.

The opening of the building’s rear also connects it to the New World Symphony’s new campus directly behind, boosting another city goal — to begin animating Lincoln Lane, the wide alley that runs along the back of businesses on the mall’s north side, and weaving together the cultural center with the pedestrian mall.