The aging five-bedroom bungalow at 1311 Apple Ave. in Silver Spring has no obvious historic significance, and its resident, Diane Amato, doesn't think of herself or her surroundings as particularly unique.

But the house Amato rents and another one directly behind it on Fenwick Lane are the last exclusively residential single-family houses left in downtown Silver Spring, a formerly low-scale suburb rapidly becoming a high-rise city.

It is happening in Bethesda and in other older suburbs as well. Single-family houses in the old downtowns of suburbs are disappearing from the dynamic, emerging landscape. Or, in these communities in transition, older houses are being used for purposes other than residential.

Today, in the rapidly changing core of Silver Spring, where high-rise office towers have created a concrete canyon, a house is no longer a home. It is a lawyer's or accountant's office or a graphics arts firm, restaurant, construction company, locksmith's, psychiatrist's or real estate office.

Dozens of houses have been demolished in the central business district. And of the two dozen or so detached single-family houses that remain, Amato's brick and frame house was the last to be occupied by its owners, and its setting could hardly be called residential.

The house is next to Fenwick Professional Park, built in 1952 as garden apartments and converted in 1980 into offices. Across the street are more offices. Outside Amato's door, Apple Avenue is a dead-end street with parking meters. Weekdays, it is jammed with parked cars that sometimes block her driveway.

When Amato's house was built -- circa World War I -- Silver Spring was starting to bloom as one of Washington's early suburbs. Residents living in squat houses close to Georgia Avenue commuted by the B&O Railroad to downtown jobs. Apple Avenue was named for orchards formerly across the street from Amato's house.

Eileene Devore's family moved into the house in 1932, when she was 10. Later, she lived there with her husband Walter and could walk to her sales job at J.C. Penney's on Colesville Road. A year ago, the Devores sold the house and moved to a subdivision several miles north.

"We were the last of the Mohicans," she said. "The people behind us moved. The Buckinghams passed on, and their house was torn down. The Burches moved to Leisure World, and their house was torn down. We were the only ones there. There was nobody to socialize with. We were just by ourselves . . . .

"Every now and then, I'll ride down Apple Avenue, and at this point I'm so happy I'm out of there. The way it is, there are no memories there right now."

The houses in downtown Silver Spring are scattered like scrub bushes among the tall trees: two on Silver Spring Avenue, two on Thayer Avenue, one on Bonifant Street. But several are concentrated around Second Avenue near the new post office and in a small cluster east of the Amtrak and Metrorail tracks along Philadelphia and Burlington avenues.

Ultimately, planners say, the houses will be razed and replaced with tall office buildings or apartment towers. They say the outcome is dictated as much by the economics of development as by any approved county plan.

"The land gets too valuable for housing. Somebody buys it, holds onto it and there's a temporary use -- until it becomes a McDonald's or an office building," said Sam Bass Warner Jr., an urban historian at Boston University.

"It's just like the farmer who plows under the old corn stalk," Warner said. "It is the way booming American cities build themselves. They plow under the past. Unless there's some organized group that wants a symbol of the past maintained, that's exactly what happens. Most Americans don't think the domestic arrangements of people in the 1920s are worth paying attention to."

Indeed, the big debate over Silver Spring growth has focused mostly on how many new office buildings will result in how many more jobs and how much additional traffic. The push is toward commercial development to revive the economically stagnant suburban shopping district that grew and thrived after World War II.

Preservationists have fought to save the Art Deco-style Tastee Diner, the Silver Spring shopping center and the Silver Theater at Georgia Avenue and Colesville Road. But there have been no efforts to preserve single-family houses built from the 1920s to the 1940s.

Clinical social worker Herman Gewisgold and psychiatrists Joel Cohen and Michael Brody paid $100,000 seven years ago for the two-bedroom home on the corner of Second Avenue and Fenwick Lane. They turned the basement into a reception area and the upstairs into offices.

"We weren't interested in a big office building. We wanted a little house," Gewisgold said. In a few years, Gewisgold said, he expects to be offered a substantial sum by a developer intending to erect a high-rise. "Maybe I'll take it," he said.

The single-family lots along Second Avenue have been zoned commercial since 1975, but as long as owners occupied them, they were taxed at lower rates. "At least we didn't tax the residents out of the area," said Silver Spring planner Jeff Zyontz. But official plans call for high-rise development, eventually.

Under current proposals, 2,000 apartment units, most with rents from $900 to $1,100, are destined to rise in parcels near the remaining houses. They will be one- and two-bedroom units, convenient to jobs and the subway.

But families seeking a traditional house will have to look elsewhere, in residential neighborhoods east and north of the commercial core.

Apple Avenue's last residential tenant is not troubled by the changes.

"I could care less whether I have neighbors," said Amato, 32, who has lived there since May. "It's great."

But the house's days may be numbered. Amato's two-year lease expires next year. The real estate agent who handled the rental and sold the owner two nearby houses said those houses eventually will be replaced with a high-rise. The owner, who asked not to be identified, said he and his partners "don't have any long-range plans," but added, "Sure, it seems that the whole area is only going in one direction." Up.