A massive foundation dedicated to enhancing Jewish education, and with hundreds of millions of dollars at its disposal, will call San Francisco home by the end of the year or in early 2006.

Jim Joseph, a phenomenally successful real estate developer who lived and invested in the Bay Area for decades, donated millions of dollars to Jewish educational projects up until his death last year at age 68.

Yet his greatest impact on the Jewish landscape may be yet to come. Joseph left much of his assets, including his real estate, development, management and construction business, the Interland Corp., to his 17-year-old Jim Joseph Foundation.

Don Lewis, Interland’s president, estimates the company’s worth could exceed $500 million. State law mandates that a foundation inheriting a business must spend 5 percent of the business’ worth each year — meaning the revamped Jim Joseph Foundation would be able to lavish $25 million or more a year on Jewish educational projects of its choosing across the country.

“Let me say this: It will be one of the largest Jewish foundations in the country,” said Alvin Levitt of San Francisco, one of the foundation’s trustees, and Joseph’s longtime friend and attorney.

Levitt estimated that establishing a California nonprofit corporation and satisfying Internal Revenue Service stipulations would occupy much of this year, if not part of the next.

The estimation of the worth of Joseph’s assets and eventual transfer to the foundation is such a lengthy process largely because of the incredible success he enjoyed in his business career.

Lewis confirmed that Interland owns more than 4,000 apartment units and nearly one million square feet of office space.

Levitt is one of the foundation’s three trustees along with Jack Slomovic, a Southern California businessman who was Joseph’s brother-in-law, and Phyllis Cook, executive director of the Jewish Community Endowment Fund.

With a board and executive director yet to be selected, Levitt was unable to say, specifically, what sort of projects the foundation would choose to fund. But he believed it would follow the pattern of large grants with large impact that Joseph established in his lifetime.

“It’s not going to be the kind of foundation that makes small grants or grants to people who come to the foundation and ask for those grants,” he said. “It’s going to look for projects which have major impact and will probably try to involve other foundations in partnerships.”

Joseph, who died of a massive heart attack in December 2003, was born in Austria, and his family moved to Los Angeles when he was a toddler.

After graduating from University of Pennsylvania’s Wharton School of Business, he began his real estate career, presciently making investments in what would become Silicon Valley. He was a partner in the development of Levi Strauss Plaza and controlled a number of prime San Francisco properties.

He lived in Woodside for many years before relocating to Florida in the 1990s, and he also maintained a home in Napa.

Slomovic described his late brother-in-law as a “financial genius.”

“He once bought a football team in Arizona. And he sold it just two or three months before the [United States Football League] folded,” said Slomovic. “He made quite a bit of money on it. He sensed [the league] wouldn’t last too long. He had a very good sense of analyzing things.”

Joseph lost relatives in the Holocaust, which Slomovic said had a lifelong impact on his attitude toward Jewish education. Through his foundation, Joseph often donated millions of dollars a year to establishments such as Jewish day schools and to curriculum development programs. He also served as the president of the Jewish Home. Yet, for a big donor, he kept a remarkably low profile.

“He didn’t like publicity. He didn’t believe in tooting his own horn. We never talked to the newspaper when we did anything,” recalled Lewis. “He didn’t give interviews. He didn’t see any merit in that.”

Cook noted that Joseph’s earlier philanthropy was limited to day schools for very young children, but, in recent years, he had branched out.

“A few days before he died, he said he wanted to touch every Jewish child,” she said.

“I’m sorry he isn’t here to be able to do this himself.”