For four decades, the Alexandria garden apartment buildings known as the Hamlets were distinguished by what surrounded them--abundant greenery and open space.

The big old trees are still there, but the Hamlets aren't, at least under that name. Since the first of the apartment buildings was built in 1958, other things nearby have changed. The locally based owner of the Hamlets, Mark Winkler Co., has built a hotel, restaurants, stores and a million square feet of office buildings in a multi-use development known as Mark Center. The Hamlets sit at the southern end of the development, and three years ago Winkler rechristened them to bring them under the corporate umbrella.

The former Hamlets account for 2,670 of the 5,000 apartment units at the development, which is just off Interstate 395 between Seminary Road and Holmes Run Parkway. With the name changes, Hamlet East became Lynbrook and Meadow Creek at Mark Center. Hamlets West, North and South became Brookdale, Hillwood and Willow Run at Mark Center. The other apartments at Mark Center are in newer, more expensive buildings elsewhere in the development.

The former Hamlets buildings, which are within walking distance of two elementary schools and Landmark Mall, have distinct personalities:

* Willow Run, originally built by the Dreyfus Brothers and acquired by Winkler in the mid-1970s, is family-oriented, offering up to 1,550 square feet in a three-bedroom unit.

* Brookdale units are attractive to singles. Older, smaller and more affordable than the other buildings, Brookdale offers a maximum size of 950 square feet for a two-bedroom unit.

* Hillwood's 800 apartments, built in the 1970s, have all-electric appliances, and are the closest to the community's clubhouse and shopping center.

* Lynbrook and Meadow Creek are surrounded by wide areas of open space, attractive to those with or without children.

Mark Center Club is the official community center. Its pool, fitness center and meeting rooms are open to all tenants. Membership is included in the rent and residents can also take advantage of a variety of classes, from gift-wrapping to parenting.

In addition to the man-made conveniences, the complex offers outdoorsy amenities. Throughout the property, there are playgrounds, large shaded spaces and meandering creeks. Within walking distance are the Ford Nature Center and the Winkler Botanical Preserve.

Mike Lynch, president of Winkler, said the apartments and their residents "mirror the demographic character of Alexandria."

And that character is highly diverse--the five enclaves are an international community, residents say. Luz Canas, who came to this country 20 years ago from Peru, said her children have friends who are French, German, Russian, Asian and more.

Monthly newsletters and occasional notices are put out in English, but when something is of particular concern, such as a recent safety recall of 2,200 dishwashers, extra notice is given in Spanish.

Regardless of their national origins, residents invariably say they were lured to their current homes by the complex's many trees as well as the area's close-to-everything convenience. The landscaping and the grounds' maintenance crew get high marks from residents. Ruth Trimble, a resident since 1976, praised the winter pansies and summer impatiens. "The grounds are always lovely," she said.

"It's so green, so quiet, so family-oriented--I can get out to play football with friends!" exclaimed resident Karen Howenstein.

Because the buildings are more than 40 years old, management has embarked on extensive renovations. The work seems to be perpetual, according to residents. Roofs were replaced, parking lots were resurfaced, kitchens were upgraded. New windows and sliding doors are planned.

Progress comes at a price, though. "You keep thinking, what's next?" said one resident.

Numerous residents of Meadow Creek said upgrading basement storage and laundry areas is taking longer than they like. Some have not had storage facilities since August.

Cindy Clare, vice president of residential services at Winkler, said the renovations are aimed at curtailing fire hazards. She added that residents have the option of temporarily using facilities at adjoining buildings during the work.

Clare said the frequency and timing of upgrades, invariably disruptive to residents, are regrettable, but a reality with older apartments.

While many residents grumbled about the renovations, others praised routine maintenance at the complex.

"They go efficiently about their jobs with no fanfare," Trimble said. "You can set your clock by their changing of filters and smoke detectors twice a year."

WILLOW RUN, HILLWOOD, LYNBROOK, MEADOW CREEK AND BROOKDALE

At Mark Center

Alexandria, Va. 22311

Each building has its own rental office: Willow Run, 703-578-7840; Hillwood, 703-578-7810; Lynbrook, 703-578-7820; Meadow Creek, 703-578-9300; Brookdale, 703-578-7830. Apartment configurations and prices vary. The chart below is a selection.

* Application fee: $35

* Security deposit: $250

* Lease term: 12 months; six months with premium

* Utilities: Gas heat, cooking and hot water included in Brookdale, Lynwood and Meadow Creek; all electric included in Hillwood; all included in Willow Run

* Amenities: Swimming pool, tennis courts, health club, renovated kitchens, dishwashers, air conditioning, cable TV, walk to shopping and restaurants

* Parking: Off street

* Pet policy: Willow Run, dogs under 25 pounds and cats with $250 nonrefundable fee; all others, cats only with $150 nonrefundable fee

APARTMENT SIZE SQUARE FEET MONTHLY RENTAL

EFFICIENCY 500 to 600 $600 to $705

1BR/1BA 680 to 1,024 $695 to $905

2BR/1BA 910 to 950 $780 to $900

3BR/2BA 1,060 to 1,550 $1,015 to $1,130