When Rinaldo and Tressa Righetti purchased a piece of property at 1000 D Street in Petaluma back in 1927, the local newspaper declared, "There is not a finer site for a beautiful home in Sonoma County."

Righetti set about building a noble residence befitting both the address and his status as manager of the Petaluma branch of the Bank of America. He enlisted Warren Charles Perry, the dean of the College of Architecture at U.C. Berkeley, to design it, a Georgian-style Colonial reminiscent of a plantation mansion, complete with shutters, cedar shake shingles and columns.

As the frame of the house went up in 1928, the Petaluma Argus-Courier predicted that it would be "one of this city's most elegant homes on one of the finest sites on the finest street."

But by 1962, when the widow Righetti was ready to downsize, the 4,719-square-foot, 11-room mansion with maid's quarters was something of a white elephant.

It was listed for sale as "Petaluma's finest home," and priced at $53,000, a princely sum at a time when the median U.S. home price was $17,200. The property taxes were a then-hefty $1,262 a year.

Tressa Righetti thought highly of her doctor, Angelo Leoni, who had a practice in town. When the father of eight, with one on the way, got it in his mind that the house would be a great birthday gift for his wife (also coincidentally named Tressa), he was able to talk the elderly widow into selling it for $46,000.

"Angelo knows that before we even bought it, every time we'd drive by I would say, 'That's my house,'" a now 91-year-old Tressa Leoni remembers.

The couple have now happily lived in Petaluma's "finest home" for half a century, raising 10 children within its aging splendor.

Tressa Leoni was sitting on the brick patio overlooking nearly an acre of formal grounds that still bear the original classical bones designed by Walter Hoff, a leading landscape designer of his day in the Bay Area. Front and center in the yard is a reflecting pond, now dry.

"The house is quite amazing," said Katherine Rinehart, a local historian who is working on a coffee table book of Petaluma's great historical architecture.

Rinehart was referring not only to Perry's patrician design, but the fact that the house has been preserved in near original condition down to the smallest detail, including the silk drapes in the drawing room and the 1920s toilet and tile in the bathroom.

"Mrs. Righetti wanted me to come over and see the house," Tressa recalled. "She liked that I didn't have any plans to change anything. She said I was the only one who came into the house who didn't want to change something. I couldn't afford it."

The Leonis even bought some of the furniture, like four upholstered chairs built for the house, still in the living room, and a set of red and green wicker furniture that has been in the sunroom since the 1930s.

About the only change made was to the kitchen, which the Leonis opened up to an adjoining breakfast room to accommodate their family of 12.

But so many of the fine details remain, like handpainted wallpaper reportedly painted by a German artist whom Tressa Righetti met at the 1939 World's Fair.

Daughter Mary Pat Leoni said her parents ran a tight ship inside, instead giving them freedom to run wild in the huge yard with their eight cousins who lived next door.

Rinehart, who is the author of "Petaluma: A History in Architecture," is deep into research on the town's treasure trove of residential architecture. She's particularly intrigued by notable architects like Perry, Julia Morgan, Albert Farr and Brainerd Jones, who helped make the city's west side so elegantly distinctive.

Much of the best can be found directly on or just off of D Steet, which features examples of just about every residential architectural style since the town's founding, from Queen Anne and Craftsman to Mission, Colonial and Mediterranean revivals as well as a Tudor by Morgan.

You can reach Staff Writer Meg McConahey at meg.mcconahey@pressdemocrat.com or 521-5204.