When you've lived half a century in a place that's hardly changed, a place that stayed grassy while brick and asphalt rose up around it, even that sacred space is transformed. It comes to embody all that isn't anymore, a rural haven that recalls dirt roads and wandering cows. And in this place -- in Smitherwood, to be precise -- each loss takes on immense proportions.

Each disappearance -- the transplanted rose garden, the sold horses -- warrants bereavement. Because things aren't supposed to change. Not here.

Now that the owners of Manassas's last large tract of land -- 93 acres, all within the city limits -- have entered into a purchasing contract with a Centreville developer, the smaller losses seem just a prelude to the grand finale. Adieu to Smitherwood. The house itself will be bulldozed, most likely, to make room for the upscale single-family homes that city officials hope will give Manassas a subtle face lift.

When the Smith family ponders the loss of Smitherwood, what it remembers is the sheer space, the freedom of rolling fields, the freedom for children to tear across the land wildly on horseback, to hook catfish out of the family pond, to bale hay for the cattle, to tinker with old cars.

Virginia Smith designed the current Smitherwood house with the help of an architect a few years after she and her husband bought the land in 1950. Sitting in her kitchen, she pulls out a century-old photograph that shows a handful of frumpy farmers posing in front of a low-roof farmhouse. This is what Smitherwood looked like as a working farm.

When the Smiths bought the land for $12,000, the farmhouse had an outhouse, no running water and a bare electric cord in the kitchen. They tore down the chicken sheds, the pig pens and got rid of the dairy equipment.

"We just wanted a place to raise our children," Smith said.

And they did. Selwyn -- a retired Prince William Circuit Court judge, onetime state senator and commonwealth's attorney -- and Virginia -- a former teacher and interior decorator -- raised four children here.

The two girls and two boys grew up on horseback. They played fast-paced hide-and-seek on their horses.

Selwyn, now 76, strapped his youngest child into the saddle and led the toddler around. The brothers tended cattle. Virginia held parties and charity benefits that attracted as many as 300 people at a time. In the winter, there was ice skating on the pond and bonfires in the snow.

Manassas was smaller; faces were familiar. Smitherwood was sheer space, and it became a kind of meeting ground for much of the community.

But outside the boundaries of these 93 acres, Manassas changed. The parcels around Smitherwood splintered into tracts of housing; Plantation Lane was paved; Sudley Road got a stop light, as one son remembers.

More recently, another housing development cropped up across Plantation Lane, within sight of the main house. The Smiths planted evergreens to block the view.

The town became a city. The people came -- commuters for whom the daily 35-mile trek to the District didn't seem so far. The burden of taxes on increasingly precious land grew heavier and heavier, until at last the Smiths feared that they would lose much of the value of their land if it was passed on to their children.

Changing times had their own unexpected consequences. A car coming down the road ceased to mean that Smitherwood had visitors; it simply meant traffic was driving by. And with more houses in the area, wandering livestock became a nuisance.

"As the city started growing, the cattle would go out," said son Steven Smith, who still lives in Manassas. "Every time the phone rings now, I still wake up in a panic, thinking that the cows are out."

To live in Smitherwood was to gird the borders against change.

Drive around the land. Roads you'd expect to continue through from one side to the other stop abruptly at the Smitherwood property line, blocked by reflective barriers for a gated community of two.

The city has planned housing on the Smitherwood property for at least a decade. Preliminary plans call for as many as 300 homes, most of which would be single-family, along with the preservation of sizable tree buffers.

"We knew it was inevitable, and I assume the way that it's turning out was the best of all possible worlds," said David Flach Sr., president of Historic Manassas Inc., recalling the parties that Smitherwood used to hold, the way it served as a meeting ground for so long. "I guess our time has come," he said.

The Smiths don't know how long they have to stay in the house because the details of the purchase aren't settled yet, Virginia Smith said. They have two other houses, one in Richmond and one in Florida, and have yet to decide whether they will buy another in Manassas.

Yesterday, after a sudden downpour, Smith opened a glass door from her den that looked out on a few withering flowers on brown grass. The air was thick. If there had been roses -- as there once were -- the scent would have hung in the air.

But the roses were transplanted several years ago to another estate, after the death of a young family friend who used to care for them, Smith said. It was one of his last requests.

"All that's left out there right now is my little peonies, which when I get ready to leave, I want to take those up," Smith said. "Other than that, you can't take the stones and the bricks. They'll probably knock it down."