Cynthia Olson smiled when visitors to her Hollin Hills home complimented her husband, Gordon, on the red 1950 Studebaker placed conspicuously in the driveway. The car is hers, but the house of the same vintage with glass walls and a huge goldfish pond in the back yard is the pride of both of them.

Down the street, Jim and Frances Killpatrick beamed as guests at their house exclaimed repeatedly over the bedroom addition with glass on four sides.

Last Saturday some of the residents of this Fairfax County community put their houses on tour to mark the 50th anniversary of their development. The 450 houses were unusual when they were built from 1949 to 1971 because of their contemporary architecture, which featured a lot of glass. Even now they look unusual compared to many communities in the Washington area that tend toward the colonial and Victorian styles.

Hollin Hills has received a lot of attention and awards since developer Robert Davenport decided he didn't want to bulldoze the trees, slice off the hills and dot the area with look-alike tract houses. Instead he allowed the rugged terrain of the forested estate to dictate where the roads would go, and houses were inserted between full-grown trees.

"I didn't take down a tree," Davenport said Saturday when he came to the house tour. "Well, maybe one or two, but not very many."

Davenport, who initially said he was 95 because that was more impressive than his true age of 94 1/2, has been invited often to return to Hollin Hills. He and his family will be the guests of honor at a 50th anniversary gala scheduled for October in Alexandria.

Hana Hirschfeld, a resident of Hollin Hills since 1963, slipped her arm through Davenport's arm and escorted him over to see the souvenirs the tour committee had to offer. There were T-shirts, tote bags, refrigerator magnets, key chains and a cookbook.

As Davenport leaned on his cane, he recalled what the area looked like when he bought the 225 acres at a courthouse auction in 1946. He said it had been an old estate set in a mature forest.

"Fort Hunt Road was dirt back then," he said. "We had no sewer or electricity; Fairfax hadn't done much about that. There were no schools south of Alexandria.

"When we had a first house to show, everything was muddy but the cars were backed up way over there," he said, swinging his cane out in a wide arc toward Fort Hunt Road.

Davenport said there was so much interest in the then-radical venture that he charged 25 cents for tours of the first completed house as a way to help pay for an elementary school for the new community. People liked what they saw, and he sold several yet-to-be-built houses that day.

After that, he said, all sales were made before the houses were built. He offered buyers one-, two- and three-level plans, each designed to fit the contours of the land.

Hirschfeld reminded him that he had donated land for the school (it has since closed and the building now is a retirement home) and that he had also set aside parkland throughout the development.

"Yes, yes, I guess I did," he said, adding, "We made the roads into cul-de-sacs so the children would have safe places to play."

A map of Hollin Hills shows just that: 11 cul-de-sacs and five roads that loop around onto themselves.

The architect for Hollin Hills was Charles M. Goodman who, Davenport said, insisted on his houses being built as designed.

"He was a tough guy to work with," Davenport said. "He was arrogant, but he was smart."

And he was successful. The residents of Hollins Hill held a party to thank him and Davenport when the development was finished.

"Imagine that happening today," said Hirschfeld. "Now residents would be getting together to sue a developer."

Residents celebrate the Fourth of July together, compete in tennis tournaments and sing Christmas carols each year. They also attend their own house tours.

On Saturday, 26-year resident Carolyn Reece bought a $10 ticket and stopped by the Olson house.

"We're on our third house in Hollin Hills," she said. "There are lots of people like us who either move to a larger house or do the reverse. We thought about retiring to Portland but have decided to stay here. We have a very livable house with the bedroom, living room and kitchen all on the same floor."

She said she was making the rounds to see what others had done with their bathrooms and kitchens.

Ron and Christine Christian, who bought a Hollin Hills house about three years ago, also wandered through the Olson house.

"We fell in love with the houses here," said Christine Christian. "I told the real estate agent not to show us any more colonials. We wanted to buy in Hollin Hills."

Gordon and Cynthia Olson said they, too, easily fell in love with Hollin Hills when they bought their first house there four years ago. Then they saw the house with the 15,000-gallon fish pond for sale and bought it a year ago.

"I like to tell people we have a house that is half glass and we don't need any curtains," said Gordon Olson. "There is a greenway that goes through the back, and we are at the thickest part of it. We can't see our neighbors, and they can't see us."

The Olsons have their master bedroom on the ground floor, with two glass walls that overlook the fish pond.

The Killpatricks bought their house 25 years ago. After the children moved out, they decided to make the house just what they wanted. In 1996 they hired architect Matt Poe to design a free-standing master bedroom pavilion in back. The result is a room bathed in light with clerestory windows and floor-to-ceiling glass on either side of a gas fireplace.

The black-slate fireplace is embraced by a mantelpiece that is more art than structure. David Sengel designed it as uneven lengths of polished wood attached to the wall but not resting on the floor.

Frances Killpatrick said the room has an almost mystical feel.

"We sometimes joke that it is built atop a sacred Indian place," she said.

She paused for a moment between greeting visitors and recalled all the time she and her husband had waited to build the addition and then the year it took to have the work done.

Meanwhile, Jim Killpatrick pointed out how the mature beech and poplar trees that shade the house also create privacy for their new room.

There is a second advantage as well, he said.

"Ivy grows very well here," he said. "We don't have a blade of grass."

WHERE WE LIVE

BOUNDARIES: Paul Spring Road to the north, Rebecca Drive and Elba Road to the west, Sherwood Hall Lane to the south, and fragments of Mason Hill Road, Martha's Circle and Fort Hunt Road to the east.

NUMBER OF PROPERTIES: 450

SALES: Bob McCan, a Hollin Hills resident and Long & Foster agent, said 21 properties have sold in the last year, for $193,000 to $350,000. There are usually 15 to 20 houses on the market, but now there's only one--and it has a contract pending.

SCHOOLS: Hollin-Meadow Elementary, Sandburg Middle, West Potomac High schools.

WITHIN A SHORT DRIVE: Community swimming pool and tennis counts, Old Town Alexandria, Huntley Meadows Park, George Washington's home at Mount Vernon.