Ever since the Presidio was decommissioned as an Army base in 1994, it has been searching for a new identity that would build on its historic past while looking far into the future. The biggest tenant, of course, will be entertainment mogul George Lucas, who will relocate about 1,500 of his company's employees to the new Letterman Digital Arts Center in 2005, at the former site of the Letterman Army Medical Center. The campus will have divisions for film production, special effects and video games.

Much less publicized is the Presidio's second largest tenant, the Bay School. An independent high school with a strong spiritual underpinning and an international outlook, the just-opened school is starting with a freshman class of about 65 students. When it reaches full enrollment in 2007, it will accommodate more than 450 students, faculty and staff. It is the first permanent school in the Presidio.

For its freshman year, the school is occupying a long, majestic white building on Schofield Road facing the bay, with porches on two floors running the full length of the building. Meanwhile, construction workers and designers are busy renovating the school's permanent home, where it will move next fall -- the 62,000-square-foot Building 35, located at 35 Keyes Avenue off the parade ground, next to the Army's former administrative center. The 92-year-old building will have a display of its history in the lobby and in one of its offices, where General John DeWitt signed the infamous order in 1942 that forced all West Coast Japanese Americans into internment camps.

"When you come to the Bay School, the building is just part of it. The kids will be citizens of a much larger community," says Malcolm Manson, the tall, urbane, British-born educator who was coaxed out of retirement to become the founding head of school. "During the admission process, they asked, `Will this be an open campus or a closed campus?' I said, `Open, for 1400 acres.'"

The Bay School doesn't need to build its own athletic facilities because it has negotiated agreements to use the Presidio YMCA and Letterman Gymnasium Complex, including the swimming pools and basketball courts. For outdoor sports and games, it will use existing Presidio fields such as those at Fort Winfield Scott. And for cross-country running, the Presidio has more than 14 miles of trails.

All students will be required to do some volunteer work as part of their education, and the school will reach out to the 200-plus nonprofits in the Presidio to provide meaningful hands-on experience. The freshman class will work with children at the YMCA and perform community service for the Presidio Trust, the governing board for most of the Presidio. The upperclassmen will get to choose their volunteer assignments from such organizations as the Golden Gate National Park Conservancy, the San Francisco Film Centre, the Gorbachev Foundation and the United Religions Initiative.

Manson, the former headmaster of Marin Country Day School and the Cathedral High School for Boys in San Francisco, has a relaxed, gentle manner and an easy laugh as he leans back in his oversize chair and shares his philosophy about opening a new school.

"The boarding school problem is to keep kids busy enough so that they don't get into trouble. The day school problem is to get everything squeezed in so the kids have a life at home," he says in his soft British accent.

Most of the freshmen ranked in the top fourth of their middle school classes. About 70 percent of them are white, and about 35 percent receive financial aid. The full cost for one year is almost $26,000, which covers tuition, books, supplies, lunch and a laptop computer. But even this amount does not meet the actual expense that the school incurs for each student.

The founders conceived the idea for a school in 1992, recruited a board of directors, and became incorporated in 1996. "We didn't have a site or money, so we had lots of opportunity to talk," says Manson, an ordained Episcopal priest. "So we said, `These kids will probably take positions of leadership around 2040. What are the incremental skills that a leader of that time will need over and beyond what you usually get in high school?' One was a confidence in the language and science of technology, one was an understanding of the future of the planet, one was an understanding of the rich nations and the poor nations, and the fourth was world religions and religious conflict.'"

The school existed only on paper until 2001. Then, recalls Manson, a knowing board member predicted that real estate in San Francisco was about to tank and said, "If we're ever going to find a site, now would be the time to look." The group took his advice, and in 2003 ended up at Building 35, signing a 40-year lease with the option of two 10-year extensions. Manson was hired as the first employee, agreeing to head the school until the first freshman class graduated. Through a combination of donations, charitable investment and a mortgage provided by First Republic Bank, the board raised $17.5 million to start the reconstruction.

The Bay School is not associated with any particular religion, but will begin each day with a meditation or prayer, led by Manson or the school's chaplain, Teah Strozer, a Zen Buddhist priest. The school's guiding precepts are based loosely on the eight principles of the Buddha.

"Religion and spirituality -- or whatever word you want to use -- fit very crucially into the development of high school students," notes Pamela Snellgrove, the school's director of communications. "They're at the time in their lives where inside, they're starting to address questions like: `Who am I? Where do I fit in?' Through examination of the variety of cultures, it gives them an opportunity to open up within themselves and share that."

With his nearly 40 years as a teacher and administrator in American schools, Manson believes that teenagers have a natural interest in ethics and an innate sense of justice, and are influenced above all by their peers. "So the function of a high school is to make sure that the ethical and spiritual conversation is going on, and then get out of the way."

Until the 1970s, says Manson, "America was considered an offshoot of European studies. And that all ended." For its required humanities course, the school covers "the whole of Asia, the whole of Africa."

He expects the Bay School's first students to be far above average in their intellectual curiosity and openness to new ideas. Although their academic background was important in the selection process, he says, "we were much more interested in how they interviewed and why they wanted to attend a start-up school. They're pioneers: they like the sense of adventure, to leave a mark on the institution."

"They will have an amazing relationship with the founding faculty," adds Snellgrove.

All students will have to participate in public speaking. Manson isn't worried that they will be too shy to raise their voices. "If you look over the kids we have now, you would wish they didn't like to talk so much!" he laughs.

Asked about how to deal with problem students, he dismisses the question with a sardonic smile. "I've always said that if you go through four years of high school and never get into trouble, there's something amiss."

When the school was ready to hire its first faculty members, it recruited nationally and got more than 800 applications for 14 slots.

Says Snellgrove: "So few new independent schools are founded. The people who are attracted and interested in a new school tend naturally to be people who are leaders, who are extroverted, excited by something that's new and full of different opportunities."

One disadvantage of working for an already established school, says Manson, is that "there's a lot of baggage. If, for example, you wanted to abolish teaching Latin and incorporate Chinese, what do you do with the Latin teacher? These schools become immensely caring communities.

"When you start a school from nothing," he adds, "you can take your mission statement and design a program for that, period. And that's liberating."