Back in 1977 when the ranch was for sale, the challenge of developing such a large ranch, still mostly agricultural, was daunting - even to a serious, deep-pocketed possible suitor like Mobil Corp. However, Bren joined a group of investors for the purchase that year and in 1983 he moved to buy out all but a few minor investors. Suddenly he had his challenge, and his destiny.

"When Don bought the company, people told him it would take 100 years to develop (the ranch)," Sim recalls. "He said he'd like to just cut it to 40, so he could do it in his lifetime. And I believe he will."

While the rule of thumb is that The Irvine Co. has about another 20 years of development - from planned and under-construction communities in Irvine to the final phases of the Irvine Spectrum - it is quickly becoming an in-fill organization. The major work is now done.

Credit for this tumbles in one direction. Homebuilder Stephen Scarborough has been building homes on the ranch for more than two decades. He is chairman and CEO of Standard Pacific Corp. in Irvine. "I don't have a strong relationship (with Bren)," Scarborough says. "But looking at it from the outside, what's remarkable about him is that he brings a new, fresh vision to every community that he approaches. It's not the same; he's always willing to do it differently and to do it better."

The company's much-copied master plan that incorporates homes, parks, schools, employment and shopping and religious centers has been refined by Bren while making him rich. His success has made him a key player in Republican politics and created a billionaire - according to Forbes Magazine's annual listing of the 400 wealthiest Americans, Bren was ranked 39th last year with a reported worth of $4 billion. That put him slightly behind Kirk Kerkorian ($4.5 billion) and slightly ahead of David Geffen ($3.8 billion).

At age 70, "he's a big hitter, as big as it gets," reports one Sacramento-based reporter who follows state politics.

But great works often include a chapter called "Irony." It is included in the book on Bren. While business decisions and good timing fill the company's coffers, he may best be remembered for leaving a majority of the ranch as open space: A builder who left a lot alone.