About 15 years ago, a Chevy Chase contractor named Bailey Adams was looking for some antique Brazilian rosewood for a home he was restoring, and a friend suggested he see Luis Marden.

Marden, then in his late seventies, was a globe-trotting National Geographic magazine photographer and writer known to be a connoisseur of exotic woods, as well as an expert pilot, scuba diver, explorer and friend of kings and sultans.

Adams already knew Marden lived quietly with his wife in a house designed by Frank Lloyd Wright overlooking the Potomac River in McLean. One of three Wright-designed homes in the Washington area, the Marden house, as it is called, seldom has been photographed or examined by scholars. For many Wright aficionados, the home remains a mystery even today, nearly half a century after it was built.

So Adams was not prepared for the experience he had when he first entered the house.

He remembers going to see Marden in autumn, negotiating his way down a steep driveway to a small concrete structure, surrounded by weeds and cut unassumingly into the side of a rocky hillside above the river.

Marden, a slight, mustachioed man wearing an ascot, answered Adams's knock on the door and greeted him pleasantly, beckoning him in.

Adams stepped into a dark vestibule, then turned to his left.

"There were 80 feet of floor-to-ceiling windows, 300 feet above the most beautiful set of rapids in the river," Adams says. "It took my breath away. I just stopped. I couldn't say anything."

Marden turned to him, totally deadpan.

"He said, 'Well, I see it has the desired effect,'" Adams recalls, with chuckle.

And so it seemed like kismet last summer when Adams was summoned to meet with multimillionaire James V. Kimsey, the America Online founder who lives next door to the Marden house. Kimsey had quietly bought the property -- in part to control the view from his own house -- from the Mardens for $2.5 million in 2000.

Kimsey wanted know what Adams thought of the house, a flat-roofed, mahogany-trimmed cinder-block home that curves into the side of the hill and comes to an abrupt point upriver, like the bow of a boat. It sits just steps away from the $12 million mansion Kimsey had recently built as a showplace for fundraisers and other charitable events for his many causes.

"I told him it was like buying a run-down farm and opening the barn doors and finding a Duesenberg in the garage," Adams says, likening the Marden house to a coveted antique car. "You have a choice: You can either turn it into a hot rod, sell it for parts, or you could bring it back to its original beauty."

To Kimsey, whatever beauty was there was hard to see. Over the years the house had been neglected as Marden and his wife had aged. The roof and large concrete planters below the house were overgrown with weeds. Inside, most of the Mardens' furnishings had been removed, but piles of books remained. Cushions in the Wright-designed built-in seats along the dining room walls were moldy and full of mice. It looked, Adams says, "like a storage shed."

That run-down house was the first thing Kimsey would see in the morning when he looked out the window of his luxe master bath.

"He was first, like, 'Knock it down,'" recalls Kimsey's house manager, Hayley Winfield. "He didn't know what he had."

Some local Wright devotees had feared that a buyer would grab the property just for its prized location and put up a mega-mansion, says Peter Christensen, a docent at the Pope-Leighey House -- the restored Wright home in Fairfax County that is now a museum. And just up Chain Bridge Road, Joan Smith -- a former Frank Lloyd Wright Foundation board member and the wife of the executor of the Mardens' estate -- wondered what designs a tech mogul like Kimsey had on the house. "Obviously he was building this grand complex for entertaining," Smith says. "I thought, 'How can a man like that understand this little house?' It's small. It's simple. It's made of concrete. I didn't know. I was going to have to find out."

When Frank Lloyd Wright and Luis Marden began corresponding in 1940, the architect met a kindred spirit and an equally monumental ego. Marden had seen a "dream house" in Life magazine that Wright had designed for the typical American family in 1938. It was just the kind of low-cost, well-designed dwelling Wright dreamed of building for the new suburban homeowner. He ultimately built dozens of these low-slung but elegant structures around the country, which he dubbed "Usonian" homes.

While Wright was the flamboyant genius whose style of organic architecture broke new ground, Marden was a self-taught man who managed to parlay an interest in early color photography into a decades-long career at National Geographic, picking up five languages along the way and writing more than 55 articles for the august journal.

Marden's exploits were legendary at the magazine: He discovered the ruins of the HMS Bounty near Pitcairn Island in the South Pacific in 1956, and later met with Marlon Brando to counsel him on his role in the movie version of the tale. He went on dives with Jacques Cousteau. Long after he had officially retired, he and wife Ethel, then in their seventies, set sail from the Canary Islands to retrace Columbus's journey to the New World, arguing that the explorer had actually landed much farther south than historians initially believed.

"[H]e is a celebrity to an eclectic circle of admirers on all continents," journalist Cathy Newman wrote in a National Geographic article titled "The Art of Being Luis Marden" in 2000. "Long ago, staffers at the magazine stopped being surprised when asked by a Mideast monarch or a mule driver in Mexico: 'Tell me, how is Luis Marden these days?' The late Joseph Judge, an editor, claimed a hermit in Alaska turned him down for an interview. He was 'saving my story for Luis Marden.'"

Ethel, now 94 and living in an assisted care facility in Arlington, was a thrilling person in her own right, recalls Luis's niece, Danielle de Benedictis, 59, a Massachusetts attorney. The couple had met at a Washington boardinghouse in 1934 and were married in 1939.

Trained as a mathematician, Ethel Mar-den had a long career at the Bureau of Standards in Washington, working on prototypes of the earliest computer, de Benedictis says. She was also a licensed pilot and an expert scuba diver, and she adored fast cars.

Ethel recalled in a 2001 interview for the Frank Lloyd Wright Archives that she and Luis had been fishing for hickory shad in the Potomac one day in 1944 near Chain Bridge when they found the site for their future home. "We were fishing down below when my husband looked upstream and saw the cliff and he said, 'I wouldn't mind living up there,'" she said. "So we got in touch with real estate people on Monday morning and found there was land available here on the river. So we bought it."

Luis had already written to Wright four years earlier, asking him for plans for a house similar to the one that was featured in Life. "My dear Mr. Marden," Wright wrote back. "We do not have plans of buildings to send out inasmuch as our houses are planned for the individual needs, requirements, incomes as well as locations of our clients . . . However, I would be glad to design a house for you."

But Wright's busy schedule and the Mardens' peripatetic lifestyle delayed progress of the house until 1952. Then well into his eighties, Wright was immersed in the plans for New York's Guggenheim Museum and other projects. He didn't visit the Mardens' property, but worked instead from topographic maps, which wasn't unusual for him at that point in his career.

When the drawings for the house finally arrived from Wright's studio in 1952, however, they were something of a disappointment, Ethel Marden said in the 2001 interview. Similar to another home Wright was designing at the time in a prairie setting, the hemicycle house -- shaped like a football -- did not fit the sheer cliff it would stand on, the Mardens felt. He'd even drawn in a place for a lily pond.

"While normally I like an 'ornamental water' very much, I think you would agree if you could actually stand at the site of the proposed house, that it would not be a good idea to place the lily pond on the terrace," Luis wrote in a letter to Wright in 1953. "The contrast to the onlooker standing at the window looking out across a peaceful pool with its lily pads down to what is literally a roaring, foaming cataract . . . would be too violent."

Wright eventually dispatched one of his apprentices, Robert W. Beharka, to Washington to oversee construction of the Marden house, as well as one he had designed for his son, lawyer Robert Llewellyn Wright, in Bethesda. The third Wright house in the area is the Pope-Leighey House, which was built in Falls Church but since has been moved to the grounds of the Woodlawn Plantation in Fairfax County.

When Beharka arrived, the Mardens made clear to him that there was another major flaw in the plans, Beharka recalls. He is still a practicing architect in Los Banos, Calif. The Mardens thought the way Wright had designed the wide terrace blocked the view of the river below for those standing inside the house. So Beharka slunk back to Taliesin -- Wright's headquarters in Spring Green, Wis. -- to break the bad news. It was a cold night when he met Wright in the drafting room to tell him the terrace conundrum, he recalls.

"I told him exactly what they wanted -- a shallow terrace that would step down," Beharka says. Wright bent over the drawings and quietly resketched a narrower terrace. Then he got up to leave, and Beharka stopped to help Wright put on his coat. The great architect sighed and said, "Don't ever get into this business."

Wright finally made it to Washington to visit the half-finished house shortly before he died in April 1959. Upon arrival, he took in the cascading rapids, turned to Ethel and murmured, "I had no idea it was so dramatic."

He seemed pleased with the construction. He used his cane -- which for much of his life served as a "perfectly superfluous" prop, according to biographer Meryle Secrest -- to point out with pleasure how the grouting between the concrete blocks had been dug out to emphasize the horizontal lines and filled in on the vertical, a hallmark of a Wright house.

Beharka served as his driver for the trip, taking him to see the Mardens and then to Bethesda to view his son's home. On the way out of town, Beharka recalls driving him to National Airport when Wright caught a glimpse of the Washington Monument outside his window. Wright said, "I don't know why they made that so pointed."

As many owners of Wright homes have found over the years, living in a work of art was not always easy. Ethel Marden said that the concrete floors cracked and were uneven, and the furnace had been improperly installed. The house cost $76,000 to build by the time it was completed in 1959 -- far more than the price tag of more modest Usonian homes.

Still, she described how the couple loved sitting at the small breakfast table overlooking the water in the early mornings, watching the birds in their bird feeders. They also fed vanilla wafers to a steady stream of neighborhood raccoons. "Our beautiful house . . . stands proudly just under the brow of the hill, looking down always on the rushing water which constantly sings to it, day and night, winter and summer," Ethel wrote to Wright in 1959. "It will . . . represent for us, as you put it when you were here, 'a way of life.'"

Yet over the years, Joan Smith -- who has served on several Wright-related boards, as well helped spearhead fundraising for Pope-Leighey's restoration -- often asked the Mardens if the many Wright scholars she knew could come and see the home. The Mardens always declined.

Smith believes the main reason was that the flotsam of their exotic lives -- fishing poles, treasures from their travels and thousands of books -- cluttered and threatened to overtake the 2,576-square-foot space. Clutter was antithetical to Wright's stern less-is-more principle, which often manifested itself in homes with a distinct lack of usable storage space, attics or basements.

"They never allowed [the house] to be publicized," Smith says. "He would say, 'I don't think I'm a good steward of the house.' At one time he had a big red canoe sitting on a table in the living room. This was the way they lived. He had things like the canoe and the egg" -- an egg of an extinct aepyornis that Luis Marden found in Madagascar -- "diving masks, books piled everywhere. He was in some way ashamed of the way they lived in the house."

But by 1998, after Luis had become debilitated with Parkinson's disease and moved into a nursing home, the couple began thinking about preserving the house.

Shortly thereafter, neighbors along Chain Bridge Road began buzzing about the large home that tech tycoon Kimsey was building adjacent to the Marden property. Now complete, the 21,000-square-foot home, "The Falls," is one of the largest private residences in Virginia.

Retired banker Eugene Smith, who is Joan Smith's husband and the executor of the Mardens' estate, thought the logical buyer would be Kimsey, who would likely be interested in preserving the land on either side of his own property. Eugene Smith ran into AOL vice chairman Ted Leonsis at a party and asked if he would find out whether Kimsey would be interested in buying the property. The reply came back immediately: He was.

Kimsey, who is 65, has been heavily involved in local philanthropic projects since he retired from AOL in 1996. He is a former Army Ranger who grew up in Arlington and served in Vietnam. He has given more than $35 million to charitable causes, including $10 million to the Kennedy Center. The maverick businessman also has traveled the world in support of Refugees International and the International Commission on Missing Persons, which he chairs. Last year he went to Baghdad to support a mission identifying bodies in mass graves from Saddam Hussein's regime.

Although he's been a big supporter of the performing arts -- he's on the executive committees of the Washington Opera and the National Symphony Orchestra -- Kimsey was not known around town as an art collector. "He owns no Pollocks. He's not a collector of contemporary American art. The greatest piece of sculpture he has is a Frank Lloyd Wright house," says his friend Bill Dunlap, a McLean artist.

Eugene Smith carefully constructed the deeding of the property to guarantee that the building could not be torn down, so razing it would not be an option -- however inviting the thought had been to Kimsey at first blush.

But how would Kimsey proceed? Would he restore the house in keeping with the original plans? Or would he renovate? Kimsey -- who says he at first did not appreciate what he wryly calls the "cult" of Wright's followers -- initially toyed with the idea of renovating the building and turning it into a guest house. Although the deed wouldn't let him make major changes to the exterior, he could have made wholesale alterations to the inside of the home if he chose.

In his office high above 17th Street NW overlooking the Old Executive Office Building, Kimsey sits ramrod-straight in a chair and remembers the first time he toured the Marden property, a phalanx of contractors and architects in his wake. "I'd say, 'Why don't we add a window here?' And there would be gasps and stunned silence. Or 'Why don't we turn the garage into an extra bedroom?' More gasps and stunned silence," he recounts in a growly way. But he has a twinkle in his eye, and one senses that he never really intended to do anything of the sort.

For one thing, he'd already fallen under Ethel Marden's spell.

The first time they met, she greeted him at the door with a firm handshake and showed off her underwater diving medals. Later, he and his friend Queen Noor, the widow of the king of Jordan, used to take Ethel to lunch at the Cosmos Club, where she was a member. Kimsey evidently found these meetings so elegant that he's moved to describe them in French: "Tres gentil," he says.

As a condition of purchasing the house, he agreed to let Ethel live there as long as she was physically able and -- a highly unusual clause in the purchase contract -- that the couple's ashes could be spread under a beech tree on the property after both their deaths. Luis Marden died in 2003.

After Ethel moved into a retirement community in 2003, Kimsey ruminated for months about what to do about the house. It was the first thing he saw every morning as he was shaving. "Its presence just spoke to me," he says. "It sat there every morning crying out, 'Don't let me sit here and degrade any more.'"

Exploring the house with Dunlap one day, Kimsey came across Wright's original drawings of the home in one of the cabinet drawers. "It was a eureka moment," Kimsey recalls. A Memorial Day weekend trip to Taliesin West -- Wright's winter home in Arizona and now home to the Frank Lloyd Wright Foundation -- to talk to Wright archivists cemented his plans to restore the house to exactly what the architect had wanted.

The restoration process had barely begun when a miscommunication arose between Joan Smith and Kimsey's staff over what to do with the Wright-designed furniture in the home. Smith says she thought Kimsey didn't want the furniture, so she set about finding suitable places for it. The large dining room table and two side tables were donated to the Virginia Museum of Fine Arts in Richmond, and two of the smaller plywood tables were sent to be auctioned off to raise money for the Frank Lloyd Wright Building Conservancy in Chicago.

This caused a mini-stink within Wright circles, because purists believe that the original furniture should remain in a Wright-designed home whenever possible, Joan Smith says. To quell the criticism, the conservancy says, the tables were pulled from the auction, and the conservancy drew up an agreement whereby the two small tables could end up back at the Marden house if the owner wants them back.

In an interview in July, Kimsey seems surprised to hear this.

"I want them back!" he says. He says he was unaware the furniture was eschewed by his staff and agrees it was a "shame." "Ideally we want as much furniture designed by Frank Lloyd Wright as possible in the house."

To get to the house now, one passes through the cavernous rooms of Kimsey's mansion and up a slight hill to the Marden house, which has been stripped of brambles and weeds to expose its curved terrace and wall of glittering windows.

Strangely, the little house sits so snugly into the side of the hill that the effect of moving from Kimsey's large home -- which he describes as "postmodern French Provincial" -- across a terrace and the few feet to the house is not as jarring as one might expect. A new copper roof now gleams where tar and gravel once lay. Wright had specified decorative copper trim in the original plans, but encasing the roof in copper is a new idea, which might give some preservationists pause.

Inside on a recent day, the house is full of workmen and smells of wood stain. Adams, who was hired to do the restoration, has taken down the African mahogany garage doors and set them on stands in the dining room to be refurbished. He shows off the trademark orange-red tile with Wright's signature by the doorway, then a handsome lamp that Beharka made of interlocking wood pieces -- similar to one that sat in Wright's office at Taliesin in Wisconsin. It will be rehung in its original position next to the large stone fireplace, which Wright saw as the spiritual center of the home.

Kimsey is trying to get the $1 million-plus restoration done and the house furnished by fall, and he hopes to have a cocktail party there soon. He doesn't plan to open the home to the public, but instead to use it for small fundraisers, parties and -- once again with the mischievous twinkle in his eye -- "romantic dinners." Divorced with grown children, Kimsey is considered one of the most eligible bachelors in Washington.

Looking back on the time when he was entertaining thoughts of redoing the house, Kimsey says, "Nobody ever said, 'Don't do it,' but to change the house was such anathema, heresy" to Wright loyalists. "Once you understand the intense devotion these people have to his work, you realize they don't see you as the owner, you're like the trustee. So I decided to restore it back to its original condition -- which by the way was cheaper than renovating -- and everybody breathed a sigh of relief."

Annie Gowen is a reporter for The Post's Metro section.