When Trudy Goodwin's grandchildren visit her home in North Fork, they play pool where beef cattle once ate from troughs and eat dinner in what used to be a hayloft. In Hillsboro, Candace Terry has turned a 224-year-old horse barn into a dog kennel, and just outside Leesburg, developer Leonard "Hobie" Mitchel is transforming a dairy barn into a community center.

In rapidly growing Loudoun County, where buildings seem to come in three ages -- new, newer and newest -- barns aren't just for farm animals anymore. The ones that have survived the county's suburbanization often owe their reprieve to their sturdy, spacious construction and, sometimes, to the triumph of nostalgia over budget.

"It is truly American architecture," said John P. Olson, the program director for barn preservation at the National Trust for Historic Preservation. "These buildings are handmade creations. Old barns remind us of hammer to the nail and hammer in the hand, and that connects us to the people who built these structures."

Goodwin, a real estate agent, knew that once her husband retired from the military and the kids grew up, she wanted to convert an interesting old building -- a lighthouse, perhaps -- into an interesting new home. She didn't know she would start with a barn until she saw the big red one standing empty in western Loudoun.

Now rows of windows brighten its upper stories, a balcony offers a view of a nearby creek and the great room is so large that she has created several sitting areas before a huge stone fireplace. Between the great room and a kitchen large enough for several cooks, the dining room has a table that can be extended to seat all 23 family members, who live in the area and gather once a month for a meal.

But when they bought it from a horseman's widow in the mid-1980s for $60,000, it was very much a barn. The horseman had bought it from a large spread, Egypt Farm, when owners decided to downsize their cattle operation.

"We had to scrape the floor out with a hoe," she said. "We evicted black snakes, bats, birds and thousands of mice" -- not to mention a "zillion" bugs.

Cleaning it took a year, renovating it another.

Terry always looked at the barn before the house when she was shopping for a farm in Loudoun in the early '80s. Her heart was stolen by a fieldstone-and-wooden "bank" barn -- a barn built into the side of a hill so livestock could enter the lower level through the downhill doors and hay wagons could roll right into the loft through an uphill entrance on the other side.

"I wanted a grand old barn even if I didn't have a particular need for it," Terry said.

But she found a need, and then another. After she renovated the house, she used the barn for sheep, which she kept for training her border collies. She gave up sheep after she went to work for a vet and discovered the scarcity of kennels in the area. So what used to be a space for four horses now shelters a dozen dogs.

Wanting to alter the barn as little as possible, she had the earthen floor dug out to make more head room and poured a concrete floor. Then she extended the loft to make a full ceiling for the lower level, where the dogs' wire-mesh cages line the walls.

"I did it this way so all the kennels and dog stuff can be simply taken out," she said, "and then you have a barn again" -- to be used as a barn or turned into a house but above all to be cherished. "There should be a law against tearing these barns down," she said. Farther west in Bluemont, Great Country Farms has recycled almost every building on a former dairy farm to transform the place into a vegetable and fruit farm where produce is sold directly to consumers who are also welcome, for a fee, to fish and picnic there.

Customers pack their produce in a former milking barn. The machine shed is used for storage. The wooden corn crib is outfitted with six picnic tables and rented for children's birthday parties. A bank barn may become an antique shop, and a horse barn will most likely berenovated and rented out for weddings and other events.

"We use everything we have," co-owner Kate Zurschmeinde said. Her brother-in-law, Mark Zurschmeinde, said they weren't sure what they would do with the dozen buildings they bought 10 years ago from the Church of Jesus Christ of Latter-day Saints, which had used the 198-acre farm as a retreat.

"We've still got another barn to use," he said, "but it will take a lot of work. It seems like we are forever repairing things."

Even in more populous and suburban eastern Loudoun, where subdivisions have overtaken many a barn, another former dairy barn escaped demolition when the owners of Lansdowne on the Potomac saw its potential as a community center.

Mitchel, president of Lansdowne Community Development LLC, said that although it would have been cheaper to build a new community center for his new subdivision, "it's nice to have some history involved."

The development is rising on what used to be used to be the Coton tobacco plantation. The property changed hands several times, and when Xerox Corp. bought it in 1972, only a smokehouse, a detached kitchen circa 1800 and a 1930s-era barn remained.

Lansdowne, which bought it in 1999, plans to use the two older buildings for office or arts space, Mitchel said. The barn has acquired two new wings that match the design and materials and that nearly double the space to 28,000 square feet.

The $6 million center, scheduled to open June 7, will have two pools, a fitness center, children's playroom, snack bar, concert hall and meeting rooms.

"It is about lifestyle," Mitchel said, "something old made to work within the new community."

Hobie Mitchel, president of Lansdowne Community Development, plans to make a community center for his new subdivision out of this former dairy barn in Loudoun County. Trudy Goodwin sits in the dining room of the barn she and her husband converted into a home in North Fork.