Lee Elsen remembers that he was skeptical about the planned location of the Watergate at Landmark condominium project in the early 1970s after venturing to the northwestern Alexandria site that then was nothing more than a gravel pit.

"That's quite a ways out in the country," Elsen told Giuseppe Cecchi, head of the firm that built the complex. Cecchi, however, assured his associate that the site was only 10 minutes from Washintgon and asked Elsen to follow behind in his car to prove it.

"We got there in 10 minutes," Elsen recalled. "At 80 miles an hour."

Few now would argue that Alexandria's Landmark area -- the two-square-mile section framed by Shirley Highway, the Capital Beltway, the city's western boundary and Holmes Run -- is in the boondocks. What later was dubbed "Condo Canyon" today has more than 10,000 condominium and apartment units, and substantially more office and residential development is virtually assured if a nearby Metro station opens as planned in 1990.

Elsen himself is a longtime resident of the Watergate at Landmark project that he played a major role in selling as senior marketing vice president for Cecchi's company. The 1,456-unit complex celebrated the 10th anniversary of its first resident last weekend, with longtime and new residents alike sipping champagne and singing "Happy Birthday" at a brief ceremony held in the development's community center at 211 Yoakum Pky.

Watergate at Landmark was the first Virginia condominium project to register with the state under a new condominium law adopted in 1974; it was a trailblazing development. Condominiums, which had been a way of life in Europe and South America for years, were steadily gaining popularity here, particularly in the Shirley Highway corridor.

In 1973 and 1974, more than 2,000 condominium and apartment units were built in the Landmark area, bringing the area's total to about 11,500 units. But the boom turned into a bust for some condominiums in the Landmark area. A glut of units combined with high mortgage rates and other economic factors forced four of the 16 high-rise condo complexes in "Condo Canyon" into foreclosure in 1975, while two others were converted to rental apartments.

Despite some periods of slow sales, however, Watergate at Landmark eventually prospered, and today it has a sense of community that often is hard to find in look-alike development projects that seem to blend, rather than retain, their individual identities. By September 1978, three-quarters of the project's units were sold before the fourth and final building was ready for occupancy and the complex was transferred to the control of the condominium owners.

With more than 3,000 residents and an annual condominium owners' budget of $5.5 million, Watergate today most resembles a miniature city, albeit one with decided luxuries, such as a full-time social director and the underground passageways that link the complex's four 16-story residential buildings.

"When I come in the gate, it's like coming into my estate," said eight-year resident Dorothy Byrd. The project is enclosed and residents must show identification at two guard gates to gain entry.

The 33-acre grounds contain an 18-hole putting green, a sunken volleyball court, a racquet club with a tennis pro, and a free-form outdoor swimming pool that was said to be the largest on the East Coast when it was built a decade ago.

Most residents agree that the recreational facilities have proved to be the strongest selling point. Uncharacteristically, by today's standards, they were built in conjunction with the residential segment of the project rather than afterwards.

"What sold Watergate back then to us were the facilities," said Brian McSweeney, a member of the homeowner association board of directors who has lived at the complex during all but a few months of its existence. "Even today, what brings people here are the indoor pools, the outdoor pools and the indoor tennis courts and the outdoor tennis courts. They're still the major attraction."

The diverse facilities and large scale of the project have attracted an equally diverse assortment of residents. A survey of the complex several years ago showed a virtual three-way age split among residents of Watergate at Landmark, with one-third under 30, one-third between 30 and 60, and one-third over 60, McSweeney said.

Initially, most units were purchased by young couples and singles, but more recently couples whose children have grown up and left home and other older couples have bought units because of the escalating cost of owning single-family homes. As a result, one of the buildings in the complex has been partly converted from one-bedroom units into two- and three-bedroom apartments.

The units now range in price from the upper $60,000s for a one-bedroom apartment to more than $170,000 for one of the larger three-bedroom units.

Residents say that Watergate's diverse population has helped set the project apart from adult-only and other special-interest condominium projects, but also has wrought some difficulties.

John Doud, a former president of the homeowners association who remains on its board of directors, said it is sometimes "almost impossible to come to a majority consensus" on whether to use association money to refurbish facilities such as a seasonal ice skating rink and exercise equipment that are not widely used.

"The board [has] to watch out for all the members without being pressured by any pressure groups," he said.

Despite such problems, Doud and others suggested that the overall sense of community at Watergate remains strong.

Board member McSweeney recalled arriving home from the hospital with his newborn son Christopher seven years ago to find 30 residents waiting at the front gate of the complex with a welcome banner.

For McSweeney, Watergate is reminiscent of the close-knit Brooklyn neighborhood in which he grew up.

"If you did anything wrong, boy, your parents found out about it," said McSweeney, president of a marketing company based in Old Town Alexandria. "A lot of that is still here at Watergate. It's very much of a community because so many of us have been here so long we've grown up together."

Cecchi, who left the Watergate development company in 1975 to start Rosslyn-based International Developers Inc., attributed the success of the Landmark project to the total community it encompasses.

"I think it was innovative in that we were selling an environment and life style rather than just a condominium unit. The condominium almost becomes secondary to the environment that we have created," he said recently.