Architect Greg Zahn hadn't meant to be at his house during the Dupont Circle House Tour last Sunday, but he got caught by the avalanche of visitors to his corner-store-turned-home on 21st Street NW when the event began at noon. The visitors lined up out in front of the vintage display window even before the house opened and then overwhelmed the 1,000-square-foot space inside.

When Zahn adjusted the horizontal shade in the skylight over his bed, a crowd immediately gathered as though to watch a performance.

Oooh, a woman said. Look at that, another commented.

Amused by the reaction, Zahn left the shade half-pulled so others could see how it worked.

"That is the least of the innovations," he said softly and shrugged, escaping the crowd that was traipsing through his novel house. Zahn explained that he had taken a "box" and carved out a living space with two lofts and a lower level, which he dug out of the basement to create a library and bedroom. To provide daylight for the newly created underground area, he removed the floor beneath the display window on the front of the building to create a light well.

Sunday's tour covered just a slice of Dupont Circle in Northwest Washington, 15 houses on or just off 21st Street NW between New Hampshire and Florida avenues NW, in an area residents refer to as Dupont West. Unlike other blocks of the historic neighborhood, where look-alike red brick or brownstone Victorian row houses line up shoulder to shoulder, the tour area is a mixture of commercial, institutional and residential buildings strung out along a street that has no coherent architectural style. In addition to individual houses, the tour included a peek at the headquarters of the Colonial Dames 17th Century. Afternoon tea was served at the nearby Cosmos Club, housed in the historic Townsend House.

Dupont Circle, named for the circular federal park of the same name, is centered on the intersection of Connecticut and Massachusetts avenues NW, about a mile north of the White House. It was developed initially in the 1870s, when wealthy congressmen and industrialists built mansions in the area. That was followed by a wave of large apartment buildings at the beginning of this century. Handsome blocks of row houses filled in the remaining spaces.

As the residential neighborhoods of the city pushed outward and suburban living became attractive, the mansions and row houses became rooming houses or were torn down. In the 1960s and 1970s, the neighborhood became known as San Francisco East and attracted hundreds of hippies who took over Dupont Circle park for impromptu political demonstrations and concerts.

Gradually, the neighborhood was rediscovered during a return-to-the-city movement that brought in gay and straight couples and young families. In the years since, property values have risen rapidly, and there are few houses in the neighborhood that have not been renovated. Nonetheless, remnants of its hippie heritage linger in odd touches of artwork painted directly on buildings.

The selection of houses on the tour included grandiose Victorians, ornate Gothic Revivals, elaborate Second Empires and Zahn's commercial storefront.

Interior designs sometimes departed from the architectural style of the exterior, as in the home of architect Michael Beidler and preservationist Douglas Loescher, in the 2100 block of O Street NW. The plain brick facade of a house, built in 1916 as rental property, gives way to an arts and crafts-inspired interior with deep-toned sponged walls and an extensive display of paintings and pieces of sculpture by local artists.

Beidler said he and Loescher had little to preserve of the original house, which was built with no ornamentation and heavily used as a rooming house for decades.

"White everywhere, the walls, the ceilings, the floors," he said. "No real detail stuff. No fireplaces."

In the dining room, they added five-foot-tall wainscoting, glazed a deep green and gold, and in the bedroom an unusual arts and crafts-inspired red and mint green glass stepped skylight. Swimming around in three of the panels were tiny goldfish.

"It's kind of unusual," Beidler said. "You don't get to see the underneath of fish very often. And when they die--we lost two of them recently--of course they turn belly-up and look the way we normally see them."

He said he fed the fish, and lit the skylight, from a crawl space overhead.

Even the back gate, which pivots rather than opening on hinges, carries the arts and crafts touch, with angled slats topped by cross-hatched trim.

Loescher, the preservationist, said he initially wanted to "save every nail" as they renovated their house but gradually grew comfortable with the idea of creating a totally new environment.

"We kept the spirit of the house and then played with it," he said. "We added wonderful detail."

Then they slipped out of their house just as the tour began. "We will tour the other houses," Loescher said. "I really like to look at the range of lifestyles."

Among others doing the same was lawyer Carol Theodore, whose 1877 Second Empire corner house was also on view. She encountered Zahn as he tried to escape his house.

"Are you the owner?" she asked. "This is amazing, what you've done. I am so pleased to meet you. I used to live across the street and watched as you started this project."

Theodore said she and her husband, Eustace, so loved the neighborhood that they left their rental across from Zahn a year ago to buy their large, three-story house down the street.

"The house was completely done when we bought it," she said. "Architect William Gridley lived there and had done it over for himself."

While she was out on the tour, hundreds of people marveled at a street-level courtyard garden on the 21st Street side of her house that is completely hidden from view by a brick wall and heavy shrubs.

"I had a dinner party last night for nine right there in the garden, and no one passing on the street could see us," Theodore said later. "Unless we play music, no one knows we're there."

A couple of hours into the event, Theodore stopped by her house to talk to the monitor standing in her kitchen. All the houses had several volunteers who answered questions and kept an eye on valuables.

As she crossed the street to visit a pre-World War I house with a full front porch and a backyard swimming pool, she said she had asked the monitor a favor.

"I wanted him to solicit color ideas for the kitchen," she said. "You know, we have a great many architects and designers coming through, and I'd love to get their advice!"

BOUNDARIES: Dupont West is a triangular-shaped neighborhood bordered by Connecticut Avenue NW on the east, O Street NW on the south and Florida Avenue NW making up the third side.

PROPERTY SALES: Twelve houses have sold in the past year, ranging in price from $230,000 to $1.8 million, and 41 condominiums, ranging in price from $35,000 to $500,000, said real estate agent Bernardo Gonsalves of Tutt, Taylor & Rankin.

SCHOOLS: Ross Elementary, Grant School Without Walls Junior High and Woodrow Wilson High schools.

WITHIN A FIVE-MINUTE WALK: Dupont Circle restaurants, galleries and shops; the K Street office corridor; George Washington University.

Let us know about your little corner of ever-greater Washington and maybe we'll tell everyone. Write to Where We Live, Washington Post Real Estate Section, 1150 15th St. NW, Washington, D.C. 20071. Or e-mail us at where@washpost.com

CAPTION: A Victorian corner row house, above, and a secluded garden down the block, right, greeted visitors on the 1999 Dupont Circle House Tour last weekend. CAPTION: Architect Michael Beidler, above, and partner Doug Loescher put fish tank skylights in the bedroom when they renovated their house on O Street. CAPTION: Architect Greg Zahn turned a 21st Street corner store into his home, adding willow branch-inspired banisters and balcony rails througho