What seems to impress guests the most is the library -- a suite of three rooms connected by arches, the center room crowned by a dome. Here, the richest man in America, whose fortune is wrung from the digital revolution, pays homage to that ancient database, the book.

After seven years of construction, the house is finally ready for occupancy. In the library, carefully crafted shelves are loaded with rare editions. Opulent chairs -- a bit more formal than the furniture elsewhere in the house -- are tastefully arranged by a leading interior designer.

A special nook has been constructed to display one of the owner's most prized possessions, a scientific notebook kept by Leonardo da Vinci in the early 1500s. Leonardo's distinctive, mysterious, backward-running manuscript cost about $30.8 million.

Huge windows look westward across a picturesque lake toward the Olympic mountains. For Bill Gates, 41, chairman of Microsoft, a young man so rich he could have any house, any view, anywhere in the world, this vista seems to say something profoundly personal. He has ordered a motto inscribed around the base of the library dome. It is a sentence from the final page of "The Great Gatsby," one of the billionaire's favorite novels (there are four rare copies on his library shelves).

The inscription: "He had come a long way to this blue lawn, and his dream must have seemed so close that he could hardly fail to grasp it."

What does Bill Gates dream of? For years, he has dreamed of this house -- a $60 million, 20,000-square-foot amalgamation of boyish exuberance and elegant good taste, of futuristic technology and a passion for old books. As it has risen on the shores of Lake Washington near Seattle, this home has fascinated tourists, inconvenienced neighbors and frustrated Gates. "The house . . . has been under construction for what seems like most of my life," he wrote in his book "The Road Ahead."

Sometime in the next few weeks, Gates, his wife, Melinda French Gates, and their daughter, Jennifer, will move into their new home. For all of the interest in the place -- Barbara Walters has pleaded for a televised tour -- America's wealthiest daddy, mommy and toddler would prefer to move quietly. The details of the home are held as close as the features of the latest Microsoft product.

As with software, however, details do leak.

In May, Gates invited a hundred CEOs, along with government officials including Vice President Gore, to a summit on technology at Microsoft, with dinner at his work-in-progress.

The visitors arrived by boat, crossing Lake Washington toward the low-slung, hill-hugging, lodgelike mansion and surrounding guest house, sports courts, gardens and garage. In all, the compound totals some 40,000 square feet spread over five acres. The boat landed at a 100-foot dock that led to the main level -- the level for entertaining -- of the multilevel house.

In the entry hall they found a long, airy stairway rising several floors. To their right was a huge room -- big enough to seat 100 comfortably at round tables for dinner -- and on one wall of this room were 24 video screens, each with a 40-inch picture tube. They can display 24 different images or just one. On this night, they played the Vienna Philharmonic in concert.

On the opposite side of the foyer was the exercise room and spa, in close proximity to the indoor swimming pool. It is no ordinary pool. Sixty feet long, with speakers built in to pipe music underwater, there is an ancient fossil imprint of a palm frond the size of a sapling in a massive slab of cream-colored stone behind the diving board -- which is made of gleaming wood, not ordinary fiberglass. The fossil motif is repeated on the floor. Sliding glass doors separate the pool area from the outdoors.

Or guests could have moved from the foyer to Gates's 20-seat private theater, with a large screen for showing high-definition television images. The theater chairs were plush and comfortable, each furnished with a small table and lamp.

Most striking, according to several of Gates's guests, was the "Northwest sensibility," an overall style in keeping with the design traditions of the Pacific Northwest, thanks in no small part to French architect and designer Thierry W. Despont. With architects James Cutler and Peter Bohlin, Despont greatly influenced the look of the house.

Gates may be brassy in business, but he's all polished wood and vaulted ceilings at home. Miles of fiber-optic cable are strung inside the walls and crawl spaces. Video screens capable of displaying computer images, standard television or high-definition TV are everywhere. But the technology is unobtrusive -- even the electrical outlets and phone jacks are hidden away.

What visitors remember after leaving are the classic touches -- like the towering old beams of Douglas fir salvaged from a lumber mill, then sanded and rubbed to a satiny finish and braced across the ceilings with iron bands.

"I wanted craftsmanship but nothing ostentatious," Gates wrote. "I wanted a house that would accommodate sophisticated, changing technology but in an unobtrusive way that made it clear that technology was the servant, not the master."

Pacific Northwest meets Leonardo da Vinci. Silicon and cellulose. Persian rugs and microprocessors.

Guests said that it is a comfortable, rather than imposing, house. Of course, these were chief executives of various companies, and they were perhaps more charmed than dazzled to find the renowned glass artist Dale Chihuly giving demonstrations of his craft on the deck overlooking Lake Washington. As Chihuly worked at his kiln, surrounded by assistants, cameras beamed live footage of his work to video screens throughout the house.

Still, one guest confessed to knocking over a glass of wine by accident. He felt embarrassed, he said, but in the way you feel when you dump wine on your best friend's carpet. It was not like spilling a drink in the Oval Office.

By building his stately pleasure dome, Gates is taking his place in a great American tradition. America's captains of industry have always constructed grand houses to match their self-images. Hearst. Carnegie. Vanderbilt. Frick.

Gates, by all accounts, has gone about his mansion-building with more modesty and consideration than his forerunners employed. The first great wave of American super-mansions appeared from the late 1800s until the start of the First World War, according to Robert B. MacKay, lead editor of "Long Island Country Houses and Their Architects 1860-1940." Families like the Vanderbilts tried to emulate the great palaces of Europe, dotting the American landscape with huge houses from Vermont to North Carolina. To assemble enough land for such estates, plutocrats typically snapped up as many as a dozen working farms. In 1910, said MacKay, two Long Island magnates bought up 400 acres of land and knocked down 60 structures to build their homes -- and one told the local newspaper that "Mr. Guthery and I destroyed the village of Lattingham to get the view we wanted."

Gates's house doesn't invade, it nestles. Built into the shore-front, it's close by the dwellings of several other top Microsoft executives. When the constant noise and dust of construction raised complaints from his neighbors, Gates responded with free car washes. He made his construction crew available to help with little projects at nearby homes.

At 20,000 square feet of living space, measuring about 384 feet from one end to the other, the Gates house is 10 times the size of the average new American home, but downright cozy compared with the behemoths of history. The Hearst castle at San Simeon boasts 90,080 square feet of house on 270,000 acres of land. The Biltmore, constructed by a Vanderbilt in Asheville, N.C., still claims the title of America's largest private home, with 175,000 square feet of living space, including 34 bedrooms.

Gates's house has about 20 rooms (not including bathrooms, hallways and closets) and six bedrooms. The upper, more private level includes a kitchen that many visitors found respectable, but hardly awe-inspiring. The big CEO dinner was catered by the Four Seasons in Seattle.

Like any house project, this one took longer and cost more than anyone anticipated. Originally, the price tag was estimated at about $10 million. But as the work dragged on, the costs ballooned.

Many aspects of the house's design reflect the taste of the young bachelor who started the project: There is a room with a built-in trampoline and 20-foot ceilings, and a game arcade. The dock is suitable for water skiing and the garage is built into the hillside, almost like the Bat Cave.

After the wedding, wife Melinda took a hand in the house plans. She redesigned the kitchen and added an office for herself. The computer systems in the house will run on Microsoft's Windows NT Server, the same software used to run powerful networks used by many major corporations.

Outside designers persuaded Gates to add another feature for toddler Jennifer and any future Gateses: They carved a stream into the back yard, to attract frogs, turtles and other creepy crawlies (not to mention native cutthroat trout that groundskeepers will stock). Near the edge of the lake there will be a salmon hatchery.

And then there are the gizmos.

Like Microsoft itself, the house is "trying to anticipate the near future," Gates wrote. "My house is being designed and constructed so that it's a bit ahead of its time, but perhaps it suggests things about the future of homes."

The principal purpose of the ubiquitous video screens, in the library, by the hot tub, embedded in the walls like so many pictures, is just that -- to display artwork. A few years ago, Gates started a company called Corbis, which has steadily acquired the rights to 17 million pictures and images. From these, Gates can select a constantly changing array of art. Bored with a picture of a 3rd-century mosaic that shows Virgil writing the Aeneid? Try Ansel Adams instead.

The art will just "know" when it's not wanted. Once the technology is debugged, the house can be programmed to please the Gates family and its visitors. Guests will provide information about their preferences in art and music. They'll receive electronic badges that will relay that information to dozens of sensors as they move through the house. As if by magic, lights will brighten or dim, the temperature will be adjusted, the pictures displayed on the video screens will change, favorite music will play on the stereo.

Much of this gee-whiz technology is still in "beta" -- which is geek-speak for "not quite there yet." Originally, for instance, Gates had hoped that the video screens would seem to vanish by displaying pictures of wood grain to match the walls. But wood absorbs light. Video screens produce light. A match was impossible. So Gates's designers added sliding wooden panels to hide the video screens when they are not in use.

And Gates originally envisioned a system that would have lowered speakers from the ceiling to waft music whenever people were nearby. The effect, unfortunately, was like the pop-up video screen on Jay Leno's "Tonight Show" -- obtrusive and a little bit silly. Gates again settled for speakers that can be concealed behind sliding panels.

In all, the new home says a lot about Bill Gates as this singular power on the American landscape moves into his forties. But the "Gatsby" quote inscribed in the library may not be entirely apt.

A children's author, Daniel Pinkwater, in a much-loved little book titled "The Big Orange Splot," put it nicely. In the book, a man defends his decision to make his house different from the others on his look-alike street.

"My house is me and I am it," he explains. "My house is where I like to be and it looks like all my dreams."

Houses are a statement, and a sign of yearnings -- especially when the owner can have any house he wants. Staff researchers Richard Drezen and Robert Thomason contributed to this report. CAPTION: Bill Gates's 20,000-square-foot mansion, matching Pacific Northwest sensibilities with technology of the near future, is nestled into the shoreline of Lake Washington, near Seattle. CAPTION: After seven years, construction is complete on Bill Gates's new home.