CAPITOL Hill--especially its "suburbs," those far-flung streets nearer the Anacostia River than the Capitol--once had many neighborhood shops. A&P groceries, small print shops, repair garages (originally for carriages, later for cars) were spread all over. Most often they were one-story buildings. Today, a number have been remodeled as homes.

Not many have come as far as the house at 708 15th St. SE, with marble floors and a swimming pool in its brick-walled patio.

The house will be open along with nine others today from 1 to 6 p.m. on the Capitol Hill Restoration Society's 25th annual House and Garden Tour. The tour (tickets $10) with jitney service and a Victorian tea at Capitol Hill Day School, starts at Eastern Market, Seventh Street and North Carolina Avenue SE. For information, call 544-3851.

Michelle Bechard, a recreation therapist, and Dr. John Kelley, a psychiatrist, both at St. Elizabeths, bought the house about a year ago. They had been living in a 13-foot-wide house, also on Capitol Hill, so this 25-by-68-foot house seemed spacious beyond belief. Bechard told a friend that at first, when she was alone, the dining room seemed too grand to eat in.

Their contemporary furniture, mostly from Scan, fits as if it had been made for the house. And their two dogs are as happy as puppies with the patio and the shed's dog door. (One dog does have an alarming tendency to eat the plants, but nobody's perfect.) Kelley has made a number of handsome stained and leaded glass panels for the house in the upstairs projects room. The house was originally rebuilt and lived in by Larry Feathers and John Humphrey, who have remodeled 20 others on the Hill and lived in a vast number of them.

"When we bought it," Feathers said, "it was one big room full of eight tons of printing equipment. We worried with the design for two years. We even went so far as to get one set through the city, and then decided to change them. I suppose there were just too many possibilities."

The final design makes good use of the house's space. They raised the room by a whole story, allowing the downstairs to have ceilings that go from 11 feet to 14. The ceilings in the living room and dining room are lower than the kitchen's because all the plumbing, air conditioning and so on are concentrated above.

You come in the front door, set back to give a bay effect. The house looks contemporary with just a suggestion of the Mediterranean.

The kitchen is to the right, the stairs to the left, the hall to the dining room, living room and patio door straight ahead. The kitchen, with a breakfast area in the front bay, has cabinets made of the groved pine once popular for screened porches. Here it is used vertically and stained, not painted. Bechard and Kelley hang their handsome copper pots on a wire rack, both convenient and handsome.

In the step-down dining room, a white cabinet holds more copper and ceramics as well as two brass samovars that Kelley bought in a post office dead-mail sale. The rosewood table, with leaves that pull out on each end, contrasts well with the white marble floor.

"The marble tiles cost about $6 a square foot from Dennis Tile when we bought them several years ago," said Humphrey. "That's really not more than some clay tiles."

Bechard likes them, but she does note they have to be carefully dried.

One whole dining wall is covered with mirror, reflecting a part of the living room and the swimming pool and patio beyond.

In the living room, which is partly open to the dining room, are comfortable, good-looking leather chairs, left over from Kelley's former private office. The fireplace is framed in marble to match the adjacent dining room. The newly upholstered couch is expected to make it back by the house tour time.

Across one whole wall, Kelley built in bookcases, using pine stair treds. "I had to do it right away," he said, "or we wouldn't have had a place to sit down for the piles of books." He installed a proper library ladder on a track to reach the high books.

Outside, the original brick walls of the back of the shop were left standing, the old roof removed and reroofed with a new open egg-crate structure. The pool is six-sided, with the longest swim 21 feet.

Feathers and Humphrey hand-dug the pool, after giving up on the laborers they'd hired. Robert Johnson gunited it. Feathers said when they lived in the house, the butterflies used to light on swimmers all the time, but Kelley hasn't seen any bugs brave the high brick walls.

Inside, a half bath is tucked under the stair.

Upstairs is a good-sized master bedroom with a handsome brass bed and two baths, one with a shower and the other with a huge tub, both big enough for communal bathing.

One room is used as a study and sometimes guest room, the other for Bechard's sewing and Kelley's stained-glass projects.

Becky C. Dyen and Carol M.C. Santos, co-chairmen of the Capitol Hill Restoration Society, say that profits from the tour go to the society's projects.