When Pierre L'Enfant designed Washington, he intended K Street NW to be a graceful, noble residential street. He gave it generous proportions to allow a carriage way, ample sidewalks, a double row of trees, front lawns and fine homes..

For decades in the last century, K Street came close to fulfilling L'Enfant's plans. But in this century the street became part of downtown -- part of the commercial center, with rows of stores, rooming houses and apartments -- just another street.

In the last 10 years, a building revolution on K Street has transformed it into the city's high-priced financial district, a reflection of the growing internationalization and upscale living of Washington as a boom town.

On the seven blocks between 16th and 22nd streets NW, teams of developers and architects have vied to create tall, massive buildings that are distinguished by garish facades of polished metal, reflective glass, exterior sculpture and massive columns. The buildings are occupied by law firms, lobbyists, study centers, unions, brokerage houses, insurance companies.

On the street level amid banks and opticians' shops, more than 30 airline companies including China Airlines, Avianca Airlines and Qantas Airways sell tickets to international travelers. A dozen high-priced restaurants serve $50 lunches and $100 dinners. Discos enliven the nighttime scene.And Washington's most exclusive Italian designer store, DePandi at 21st and K streets, displays $500 suits by Krizia and Basile.

Out on the street, messengers on French bicycles zoom by men dressed in three-piece gray suits and women in suits with split skirts. Secretaries and clerks inspect the knit hats, African jewelry and flowers for sale at the vendor stands.

People who work on K Street seem to agree they like the activity of the street. But there the agreement ends.

"This street is the pits," said city planner David Habert, who works in the new International Square building at 19th and K streets. "The architecture is poor. It lacks a human quality. I feel as though it creates a barrier in the middle of town."

Energy consultant Elizabeth Devine, however, likes the clean, new look of the street. "The public transportation is convenient and the restaurants are great. I take clients to Tiberio or Bagatelle," said Devine.

Ten years ago, K Street was an area of small businesses and vacant lots. Today it is the fast-paced, congested business center of Washington. Its supporters see it as a huge commercial success and note the high occupancy rate of the most expensive office space in town ( $14 to $16 per square foot). Its detractors see it as a chillng vision of the Washington of the next 20 years.

Washington architect and critic Arthur Cotton Moore said K Street often is described as "sterile, cold and hard. And that means a lack of quality, a minus in quality."

"We have had too much success in the real estate market. Anything you build, you can rent. The K Street buildings vie for attention with funny decoration and that is architecture at an absurd level," Moore said.

However, he is quick to point out that K street is the result of several factors, including strict imitations on height (130 feet) and use. With all that, he says, "boxes are pretty much what you will get," he said.

In addition, he said, the buildings are constructed with no initial notion of who its occupants will be. "That, plus the zoning and the lack of demand for anything better by the public, means you get sameness and dullness," Moore said.

Moore predicts that future commercial development in the downtown area will resemble the canyons of K Street. Already, 90-foot high rises extend to the north and south of K street along 19th Street. Buildings reaching 160 feet in height -- about 16 stories -- have been approved for the Pennsylvania Avenue redevelopment area.

The K Street look has become so pervasive that owners of at least two older buildings have tacked on fake K Street facades. One of these buildings, at 1910 K, was a seedy warren of well-worn offices. In 1972 Sen. George McGovern used this building as his presidential campaign headquarters.It is now faced with red brick and black glass.

Vlastimil Koubek, the architect of the 1 million-square-foot International Square and three other K Street structures, said the street "may not be the best, but it is good and it is desirable."

"Good architecture . . . has to fit the fabric of the city and be functional inside and make economic sense. The most wonderful building in the world is not going to get built if it will not make money," Koubeck said.

Bryon Black, of Weihe, Black, Jeffries and Strassman, the architectural firm that designed six K Street buildings, says the K Street look is the "result of a lot of people demanding a lot of space at a time when no one wanted to be east of 16th Street. K Street, with its 130-foot height limit, higher than most areas of the city, and favorable zoning, became the street to develop.

"Those buildings were designed to be formal, so hard materials were chosen. There is now a trend away from that and toward softer materials and less formality," Black said. "If we were to do them over, we would do them differently now."

The K Street builders did not incorporate any of the older buildings into their new structures. This practice now common in Philadelphia, Boston and other parts of the country, is finding slower acceptance among Washington developers.

"All buildings are additions to something else already built," Moore said. "Old buildings can increase the design potential. On K Street everything was leveled.People miss the continuity of the old when everything is new."

Koubek says that historic buildings should be saved, but not if they will be neighbors to a high-rise. "There is no place for little buildings next to big buildings. They do not go good together," he said.

In the mid-19th century, K Street was a street of three- and four-story mansions and row houses. Still on the outskirts of town then, it was a very fashionable address. Society pages of the local newspapers reported on the grand parties, the formal weddings and the important visitors to the homes of the rich. Gov. Alexander (Boss) Shepherd entertained in his house with its silk-upholstered walls at the corner of Connecticut and K. Two blocks away, Adm. George Dewey entertained in his Second Empire mansion, where the Capital Hilton Hotel now stands.

At the other end of K Street at 21st Street, farmers and food merchants ran a highly successful market patronized by Georgetown and K Street residents.

By World War II, many of the homes had been converted to apartment buildings, rooming houses and commercial space. The well-to-do residents had moved on as the city expanded into the Maryland and Virginia suburbs.

During the '50s, many of the houses were torn down and replaced by larger commercial buildings, hotels and parking lots.

The market fought off destruction until 1965. By then the city government had approved commercial zoning for K Street, and large scale demolition and development became the new reality for K Street.

The demand for commercial office space and the willingness to pay high rents has brought affluence back to K Street. The one Italian and the many French restaurants in the financial district easily fill their dining rooms, with some establishments charging an average $50 for lunch for two.

Jean Pierre at 1835 K Street was the first expensive French restaurant to open in the area. Jean Michael, the manager, said, "We located here nine years ago because we heard of the coming development. We gambled but it has paid off. This location attracts people to us."

"K Street is now a hot spot for restaurants," said Jacques Scarella of Le Bagatelle at 2000 K Street. "We were worried when we opened seven years ago, but within two months we were busy every day. Now everyone wants to locate their restaurants here. Whenever there is a new building, someone tries to open another restaurant."

Renato Dechiara of Romeo and Juliet at 2020 K Street thinks the rent is "outrageous, but it is comparable to the trade we get. We know this is a good area, and 50 percent of a restaurant's success is location."

The people who are able to afford club memberships and expensive meals are no help to the street vendors who line the north side of K Street. One 50-year-old vendor, who did not want to give his name, sells winter hats, scarves and umbrellas.

"Those rich people, the ones who earn more than $15,000 a year, don't shop at our stands. It's the people waiting for a bus or the maids and construction workers who will buy a $2 hat on the street," he said.

A block away Tony Oliver, 55, was selling flowers and fruit. He was going a brisk business in 35-cent apples and $1.50 bouquets of flowers. "In the morning, the women in the business suits buy the flowers," he said. "Then at night, its the men in business suits who stop for flowers."

Carlos Ruival, district manager of Aerolineas Argentina at 1825 K Street, stood at his office door watching a silver Mercedes 280SL being towed from an illegal parking spot.

"We were the first airline office to move west of 18th Street and now we are surrounded. The airline offices always group together in any large city for the convenience of the customer. In Washington it started with the airlines locating in the (Capital Hilton) hotel," he said.

Ruival, an Argentine citizen, sees K Street and its occupants as proof of the "Europeanizing" of Washington. "In the last 10 years it has grown in buildings and in sophistication," he said.

Architect Black, taking the long look at K Street and its unique buildings, said "The 1700 and 1800 block of K Street are pure 1960s architecture. Maybe someday people will want to preserve that."