For as long as the neighbors can remember, Dupont Circle has been in a struggle for its survival.

In the 1960s, residents fought master plans that called for knocking down houses in the neighborhood and replacing them with high-rise apartments and freeways. By the mid-1970s, commercial encroachment already had claimed many of the great mansions that once occupied the southern side of the circle.

Builders now are looking at choice parcels north of the circle, across Massachusetts Avenue, where rows of restored 19th century Victorian town houses and neighborhood bistros, art galleries and retail establishments combine to make Dupont Circle one of the most cosmopolitan addresses in Washington.

"What Dupont Circle is, is the living downtown that people would like to see down on Pennsylvania Avenue," said Thomas Gregory Ward, president of the Dupont Circle Citizens Association. "The mix of residences, businesses and commercial is really the textbook mix. That's what makes it so attractive."

"It is that balance that we are so committed to maintaining and preserving," Ward said. "It can be lost so easily."

If the past is any guide, Dupont Circle should do just fine. Its residents are intensely proud of their houses and display a civic zeal that would be the envy of many Washington neighborhoods. Resident successfully challenged commercial pressures in the past -- in 1978, the District granted the neighborhood historic status -- and resident again are girding to challenge those pressures.

In March, the D.C. Zoning Commission is scheduled to hear a proposal that would severely limit the ability of developers to erect large commercial structures in Dupont Circle. The proposal was a response to a flood of proposals last year for so-called "planned unit developments" in Dupont Circle that enable builders to circumvent existing zoning guidelines.

The most disputed was a proposal by Riggs National Bank to construct a 10-story office building at the circle on Connecticut Avenue, which would wipe out a block of small retail establishments and cross an unwritten demarcation line against new large-scale development north of Massachusetts Avenue.

"What you'd have is monster buildings ringing the circle," said Jack Evans, a lawyer and commissioner of the Dupont Circle Advisory Neighborhood Commission. "It is only a matter of time before they start marching up north."

Evans and other civic activists are trying to preserve one of the city's most architecturally distinctive and historic neighborhoods. The circle itself, called Pacific Circle in the 1880s, now contains a marble white fountain honoring Civil War hero Adm. Samuel Francis DuPont and serves as the intersection for three grand Washington avenues: Massachusetts, New Hampshire and Connecticut.

Today, Dupont Circle's benches and chess tables attract an eclectic assortment of young punks, visitors from the nearby shops and restaurants and wandering homeless people. But at the turn of the century, the circle was one of the city's most fashionable neighborhoods, surrounded by great mansions built by an elite group of powerful industrialists and politicians, such as Nevada Sen. William M. Stewart and California miner Thomas Sunderland.

While some of these houses have been torn down, many remain -- including the Walsh-McLean House at 2020 Massachusetts Ave. NW, now the Indonesian Embassy, and the Patterson House at 15 Dupont Circle NW -- and offer outstanding examples of the Beaux Arts style of architecture popularized after the turn of the century.

Some of the houses can be viewed each October during the popular Dupont Circle house tour, an annual event which now draws more than 1,000 people for a special look at some of the District's best restored homes.

Over the years, Dupont Circle has undergone dramatic changes. In the latter part of the 19th century, row houses were erected along R and S streets and other routes north of the circle and became homes both to diplomats and professionals and to tradesmen and laborers.

During the housing shortage of World War II, these houses became boarding homes and in turn rooming houses for the students and other counter-culture types who flocked to the circle during the 1960s and 1970s.

Few of those boarding houses now remain. Beginning in the 1970s, young professionals gradually beganbuying and renovating the Victorian town houses, contributing to a neighborhood renaissance that continues to this day. Fixed-up shells that once sold for less than $50,000 now cost as much as $400,000 to $500,000.

While a mix of income groups still reside in the neighborhood, which includes many condominium units and some apartment buildings, Dupont Circle has gone upscale in recent years and has become expensive for younger families with children.

Residents speak in glowing terms about Dupont Circle, citing in particular the convenience and vitality of urban living.

There are essentially three commercial corridors in the Northwest neighborhood -- along P Street, along Connecticut Avenue and along 17th Street -- each with its own distinctive character, as well as liquor stores, dry cleaners and other conveniences.

P Street includes some of the District's most popular gay bars, while late-night strollers can frequent the 24-hour bookstore Kramerbooks and nearby restaurants on Connecticut Avenue.

Having undergone a renaissance of its own, 17th Street boasts some of the neighborhood's longstanding fixtures, such as La Fonda Mexican Restaurant and Trio, where visitors can buy one of the cheapest breakfasts in town.

"I like the big density, the excitement, the convenience," said Dudley Canada, an architect and longtime Dupont Circle resident. "This is as urban as you can get in Washington, D.C."