Diane Keaton likes to look at houses even when she is not in the market to buy.
The Oscar-winning actress grew up in Santa Ana during the housing boom of the '50s, going to open houses with her father, Jack Hall, a civil engineer who became a real estate broker. He liked to explore tract homes mushrooming in the fields of Orange County, and she valued her time with him, away from her younger brother and two sisters.
"My father took me to see model homes, which I thought were palaces," Keaton said recently as she sipped a Shirley Temple in the Polo Lounge of the Beverly Hills Hotel.
The child in her still loves looking at houses, but she no longer marvels at models. She is fascinated now by homes that are old, well designed and, sometimes, rundown.
They're nothing like the investment properties her father bought. "The most he would pay was about $15,000 for a tract house," she said. "He didn't buy because a house was beautiful or old. For him, buying a house was a means to make money. He was very practical.
"I gave myself permission to be impractical all of my life."
Keaton loves Spanish architecture and is obsessed, she says, with Spanish Colonial houses. "I'd buy every one of them that comes up for sale if I could afford it," she said. Like her dogs -- a huge Newfoundland and a little mutt rescued from the pound -- houses are salvaged and nurtured under Keaton's care.
It's a practice she began in the late 1980s after her father became ill and she decided to move from New York to Los Angeles to be closer to her family.
She was living in the San Remo, Art Deco twin towers in Manhattan, when she started house hunting in the Hollywood Hills. She was soon enamored of a Lloyd Wright-designed house built in the '20s near Griffith Park. The house belonged at one time to silent-screen star Ramon Navarro.
Her father told her she would be insane to buy the house because it needed so much work, but she bought it anyway. Then she spent so much money on it that she wondered briefly if her father had been correct.
She had lived there four or five years when he died. Since then, she has emulated her father, looking at houses at every opportunity.
While in the process of adopting her daughter, Dexter, now 7, she bought "a Wallace Neff that the seller had owned for 50 years." Like the Navarro house, the Neff-designed Beverly Hills house was built in the '20s.
"People thought it was a teardown," she said, "but I redid it." New York designer Steve Shad- ley, who grew up in Los Angeles and studied to become a scenic artist and backdrop painter, assisted her.
Keaton worked on restoring the Spanish-style 7,000-square-foot house for several years. "We made it as authentic as we could," she said. Then she sold it to Madonna in June 2000 for $6.5 million.
The sales price was a testimonial to Keaton's taste, which extends to decor: She collects rustic, Monterey-style furnishings and hillside pots made of concrete with tile designs around the rims. All were made in California during the 1920s.
The Neff house, with eight bedrooms plus a guesthouse, wasn't even on the market when Madonna bought it. Keaton had to be persuaded to sell.
Then came a surprise: Keaton couldn't find another house to buy, so she rented one. And she's still renting. After she sold her house to Madonna, she adopted a son, Duke, who is 2.
While renting on the Westside, she eventually bought two houses: one in Laguna Beach, the other in Bel-Air.
The five-bedroom, 3,000-square-foot Laguna house is a getaway built in the '20s. Keaton purchased it in September 2001, refurbished it and is thinking of selling. "I'd like to push toward the ocean, inch by inch," she said.
Her father liked to skin-dive in Laguna, and her mother would bring sandwiches to the beach for the children. "So I know the area," Keaton said.
She bought the Bel-Air house last year in the $6-million range. The Spanish-style house, built in 1928, is a U-shaped hacienda with two stories on one side. It has six bedrooms in 7,000 square feet and is on nearly an acre. The house, once owned by director Peter Bogdanovich, is being restored, and Keaton hopes to complete it this summer.
Not one to rush, she took almost a year to get started on the Bel-Air house and two years to start restoring the house she sold to Madonna.
Keaton is philosophical. "You have to get to know a house and try to keep its integrity. I try to honor the architect," she said. "I love to go into an empty house. You look at the house and start to feel what it might need."
In addition to launching the Bel-Air restoration, she has begun filming a movie starring opposite Jack Nicholson and Keanu Reeves. At the same time, her production company, Blue Relief, has completed a movie for HBO called "Elephant," which Gus Van Sant directed, about violence in schools.
But the single mom, in her 50s, still makes time to look at houses.
"She has her eye on another property in Laguna, which might determine if she sells the current one," said Keaton's business partner, Bill Robinson, who earned a real estate broker's license and invests in property when he's not writing and producing films.
Closer to Hollywood, Keaton is ever watchful of great old houses that could be reduced to splinters. Although not considered architecturally significant, the longtime Beverly Hills home of the late actor Jimmy Stewart was a piece of Southern California history that she was sorry to see destroyed.
She also frets over the fate of the once-swanky, now-shuttered Ambassador Hotel on Wilshire Boulevard. Of her five published books, "Reservations" is a collection of photos she took of hotel lobbies.
But her focus is on houses, and she recently saw one in Hancock Park that both she and Madonna wanted to buy, she said. The owner, a producer, wouldn't sell.
"It's my maternal instinct to save these old houses," she said, "but I know it is safe in his hands." Not surprisingly, Keaton is on the board of directors of the L.A. Conservancy, a local historic preservation organization celebrating its 25th anniversary this year.
The variety of neighborhoods from Santa Barbara to San Diego reminds her that local communities can express their pride through preservation.
"We need to do more of that here," she said. "There are so many house treasures, unsung gems, all over Los Angeles."