Until quite recently in San Francisco's history, the Civic Center area was known primarily for its government buildings, dominated by the golden beaux arts dome of City Hall. The only major cultural institutions in the neighborhood were the War Memorial Opera House and adjoining Herbst Theatre, the old San Francisco Main Branch Library, and the Civic Auditorium, now renamed for Bill Graham.

But starting in 1980, when Davies Symphony Hall opened as the showplace for the symphony and the San Francisco Ballet, the area has blossomed into a performing arts mecca. In 1984 the New Conservatory Theatre Center moved to 25 Van Ness Avenue. In 1996 came the new Main Branch Library with its Koret Auditorium and Fisher Children's Center presenting dozens of free shows each year. Next, City Hall was restored and reopened, with a new emphasis on live performances, events and art exhibits. Last spring the Asian Art Museum relocated to the area from Golden Gate Park. And last November, voters approved a bond that will finally enable the School of the Arts, the city's public high school for aspiring artists, to make its long-planned move to 135 Van Ness.

But before that happens, a bigger piece of the jigsaw puzzle will be put into place one block away, at 50 Oak Street. That's the address of a six-story neoclassical building with fluted columns on its facade and an ornate ballroom occupying its center like the cherry in the chocolate. Built in 1914 by the Archdiocese of San Francisco, it first housed the Young Men's Institute, a recreational and athletic club. Then it was sold to a private individual who leased it out for office space, art and dance studios, while the ballroom went largely unused.

Buildings, like people, sometimes get a second chance to reach for greatness, and that's what happened when the San Francisco Conservatory of Music acquired the site in 2000, along with a smaller building next door at 70 Oak Street. The conservatory, the West Coast's oldest and most prestigious school for training professional concert musicians, had long since outgrown its quaint Ortega Street campus. Thanks to a successful fund-raising campaign, the Oak Street site is now being converted into a state-of-the art superstructure that will become the conservatory's new home in the fall of 2006.

The new building will total 91,000 square feet, compared to 38,000 now. The ballroom will become a concert hall seating up to 450 people, compared to 336 in Hellman Hall at the old campus. The new school will have 33 more practice rooms for students, 11 more studios for faculty, and two more recital halls. It will lose its parking lot, but compensate by its proximity to BART. And those are just the cosmetic changes.

"I think the improvements are going to be internal and external," said David Tanenbaum, chair of the conservatory's guitar department and one of the nation's most revered classical guitarists. "First of all, conservatories are urban animals, and they belong in the centers of cities where artistic activity is going on. Right now the school is in a residential neighborhood in the Sunset. There are many fabulous concerts going on out there, but it's off of a lot of people's radar screens. And I think once we move downtown, the visibility and allure of the school will increase enormously.

"And then internally, we've become sort of masters at using space right now," he continued. "We are completely maxed out, and people find very creative ways to make offices and find practice times. A lot of my students pull up a chair and a music stand in the hall and they're practicing there and on the couches in the lounges. ... There suddenly will be enough practice space and enough bigger rooms to teach in, and we will now have three concert halls. The possibilities are tremendous."

The school expects to expand its enrollment now about 300 full-time students and broaden its course offerings, perhaps branching out into jazz and world music. Another advantage, added Tanenbaum, will be its sudden accessability to world-class artists who come to San Francisco and perform in the Civic Center area.

"It will be much easier for us to get them to come by and give master classes and even just visit when they're around. Like I know [guitarist] John Williams pretty well, and last time he was in town, I said, 'Why don't you come by and just meet with the students?' And he said, 'Well you know, I feel I'd just rather go for a walk in Chinatown.' But he will be playing a couple of concerts in Herbst Theatre in I think April '05, and I can call him again this time and say, 'John, we're right down the street. I'll come get you.' It won't be open yet, but at that point I could probably take him for a walk and show him the digs."

Bright yellow banners announcing the "future home" of the conservatory now adorn the facade of 50 Oak Street. The interior has been stripped to bare concrete with the exception of the ballroom, which is being restored, acoustically improved, and outfitted with theater seats and a stage.

"You can't replicate this kind of plaster work," said Matt Guinan, the boyish senior project engineer for Swinerton Builders, which is overseeing the $80 million construction job. He pointed to the salmon-colored Grecian columns rising almost 35 feet to the ballroom ceiling and the elaborate decorative trim. The room seemed as vast as the Sistine Chapel.

The east and west walls, the roof, and even the columns holding up the building will be replaced with seismically safe materials, and the structure will be expanded into the empty lot next door. The basement, which once held a swimming pool and basketball court, will be dug deeper to create two full floors below street level. The rooftop will be landscaped and made into a terrace, and the school library on the sixth floor will be open to the public for free.

"This is easily going to be the most complicated project I've done, and I believe one of the most gratifying," said Thomas Bradley, the project manager, who coordinates the 40 to 50 subcontractors hired for different facets of the job. "It's got all the challenges you could ever want. It's got restoration work, shoring and underpinning, brand new work, concrete, steel, shotcrete that's concrete applied with a pneumatic gun. And the nice thing is that this will be something where I can actually come back to the facility after I've completed working on it, and attend performances here. ... It really is going to a Class A place to be."

Conservatory students now perform more than 375 concerts a year, most of them free. For audience members, perhaps the most important innovation of the new facility will be the acoustics. To get the best possible sound, said Carla Pasqualini, the conservatory's director of communications, "our president Colin Murdoch and some faculty did a road tour and visited some of the major performing halls around the country and listened to music being performed there."

As a result of their research, the school hired Kirkegaard Associates, which has done major acoustical work for Davies Hall, the Chicago Symphony Center, Carnegie Hall in New York and the Barbicon Concert Hall in London. The company uses sophisticated computer software to generate 3-D models of sound patterns and make architectural changes to get the best results. To help the students, it installs fabric panels in performance spaces to compensate for the lack of an audience, so that rehearsals in the halls sound the same as full-house concerts.

Pasqualini, a pixieish music school veteran from Australia, said that the practice rooms offered a different acoustic challenge: "They wanted them to be sound-proofed, but not completely quiet so it would sound absolutely dead." Each room will be on a suspended floor walled with air gaps to block off the sound, so that students in adjacent rooms can practice their own pieces at their own rate without distraction. But some of the sound will purposely be audible in the hallway to preserve the atmosphere of a music school.

The one person most responsible for making the new facility a reality is an anonymous female member of the school's board of trustees who gave $10 million to get the project started. The next largest benefactors were conservatory alumnus Gordon Getty and his wife Ann, the late Phyllis Wattis, and Barney and Barbara Osher of the Osher Foundation. They jointly pledged $9 million in a challenge fund, which must be matched by an equal amount from other sources. The new pledges are coming in ahead of schedule, and the conservatory has raised more than $39 million already toward its final goal of $65 million.

The San Francisco Conservatory of Music was founded in 1917 as a piano school in a private home and incorporated as a conservatory in 1923. It has occupied its rambling, canary yellow Spanish Revival style building at Ortega Street and 19th Avenue since 1956. Before the conservatory moved in, the facility was called the San Francisco Infant Shelter, and provided full-time, temporary boarding of young children whose families were unable to care for them. It stayed in operation from the Great Depression until World War II. No buyer has yet stepped forward to take over the site after the conservatory leaves, but probably, like 50 Oak Street, it will be reborn as something completely new.

The move to Civic Center is expected to raise the conservatory to the same level of prominence as the other major cultural institutions already there. Connections will grow between artists-in-training and established stars, and young performers will get a new impetus to pursue their dreams as their importance to the city is more appreciated. In the words of one alumnus, the late violin virtuoso Isaac Stern: "Music is not an acquired social habit to be taken once or twice a week. It is a way of life that is basic to any civilized society. "

For more information about the San Francisco Conservatory of Music, check the Web site at www.sfcm.edu.