As a teenager in the early 1950s, Carole Schaffer spent weekends at San Francisco’s Presidio Theatre, where for a quarter a pop she would watch the films of Bing Crosby, Marilyn Monroe, Frank Sinatra and other stars of the era.

So when she learned the old movie house in the main post of the historic Presidio was reopening over the weekend after being shuttered for nearly a quarter century, the 80-year-old San Mateo resident jumped at the chance to return.

But what she encountered Sunday with hundreds of other visitors at an unveiling for the newly restored theater was a far cry from the simple building of her youth.

“It’s spectacular,” she said. “I’m just so amazed how gorgeous it is.”

Sunday’s open house capped a weekend of festivities celebrating the revitalized 600-seat venue that already has a full fall schedule of live music, dance and theater along with other performing arts and classic films.

The theater was built in 1939 under the New Deal-era Works Progress Administration as an entertainment center for soldiers stationed at the former military base. While the building mostly played films of the era, it also hosted USO shows by the famous Bob Hope and Jack Benny.

In 1994, when the Army pulled out of the Presidio, the Spanish Colonial Revival-style building was stripped and left to rot. But five years ago, Peggy Haas stepped in to save the place.

The daughter of Levi Strauss & Co. executive Peter Haas began the $40 million project to renovate and upgrade the historic venue thanks in part to a fund her father left for her when he died 14 years ago.

“The theater is happy to be alive again,” Haas said, beaming among the guests Sunday.

The restored theater is part new, part old and stunned all who visited. The performance space is both grand and intimate, with new seats and carpet along with a larger, deeper stage that can accommodate acts big and small.

The Presidio Pop-up Orchestra played songs by New Deal-era composers like Aaron Copland, Ernst Bacon and George Gershwin as guests bobbed along in their seats Sunday afternoon.

The day before at an opening gala for the theater, performers from “Beach Blanket Babylon,” the San Francisco Girls Chorus and Chinese dragon and lion dancers wowed the packed house, said Bob Martin, the theater’s executive director.

“The space is really welcoming people,” he said. “It didn’t like being shuttered all those years.”

Over the past two years of construction, workers renovated the theater, making sure to preserve its legendary acoustics, while adding new backstage dressing rooms for performers, a rehearsal space with floor-to-ceiling mirrors, an outdoor plaza and catering facilities for events.

Walt Falconer, 59, was in the Bay Area from Houston over the weekend to visit his younger brother David. They lived in the Presidio when their father was stationed in Vietnam during the war and used to see films at the theater.

“It’s nothing like the theater we used to go to,” Walt Falconer said, recalling the time his family walked out of “Let It Be,” the 1970 Beatles documentary that accompanied the famous final release by the Fab Four.

“This is pretty cool compared to when we used to come here,” he added. “‘Classy’ is the word I’d use to describe it.”

Evan Sernoffsky is a San Francisco Chronicle staff writer. Email: esernoffsky@sfchronicle.com Twitter: @EvanSernoffsky