Matthew Plagianes stood at one of the few un-peopled corners in Adams-Morgan yesterday to take in the sights and sounds that transformed his polyglot neighborhood into a rollicking, overgrown block party.

Nibbling on a Bolivian dish, the 33-year-old data technician said he can't stand crowds, but he gave the annual festival an enthusiastic nod of approval.

"It's just once a year and it's a lot of fun," Plagianes said. "It's always good to have people come together for good reasons, and this is a great reason."

The 260,000 people estimated by organizers to have jammed a six-block stretch of 18th Street NW seemed to share his sentiment. The annual Adams-Morgan Day offered a perfect reason to venture outdoors, until the skies unleashed a downpour of rain and hail in the early evening, abruptly halting the festival and sending spectators scampering for cover.

The end-of-the-summer blowout attracted everyone from churchgoers in Sunday suits to punk rockers with shock-wave hair. People stared at other people. They swayed to the beat of live music on five stages. They strolled with heads buried in paper plates piled high with culinary offerings from the scores of vendor booths: alligator subs, barbecued shish kebabs, red beans and rice.

"This is great," said Kathryn Davis, 60, of Bethesda, dressed for the occasion in a "Don't Worry Be Happy" T-shirt. She said her 25-year-old daughter had persuaded her to come along, but she didn't need much prodding. She did a little jig to reggae music as she made her way down 18th Street.

Melvin Crenshaw and Alan Wiley got up early yesterday for the Trident Bike Tour in Rock Creek Park. They wrapped up a day in which they had biked 22 miles in an hour and 14 minutes with a tour through Adams-Morgan.

"This is really one of the best things the District has," said Wiley, 32, a geographer. "It shows a good side of D.C. that you don't see very often -- brotherly love."

As gospel music swelled from one stage, Elizabeth Jones, 72, closed her eyes and let out a sigh. She had just left an invigorating service at Goodwill Baptist Church a few blocks away and relaxed on a grassy slope near the gospel stage, which had fierce competition from screaming children on the nearby carnival rides.

Jones said she has attended the event every year since it began as a modest community gathering in 1977.

"They've got some very good singers -- oh my Lord," Jones said, holding her hand to her chest. "You couldn't beat this. This is great."

While Jones and others reveled in the sights and sounds, some spectators became walking, talking stories of their own.

Russell Hirshon, a 29-year-old performance artist, got attention from passersby who recognized his bewildered-looking face from his political poster, "A Conscious Choice for an Unconscious World."

Hirshon, who said he plans to be a write-in mayoral candidate, said he came to Adams-Morgan Day to tap into what people were thinking. "We're trying to bring a little more interest into the political scene," said Hirshon, who is also a bartender at the Fifth Column nightclub in Northwest. "I just want people to get involved. If I make one more person go out to vote, I've succeeded."

As the crowds grew dense in mid-afternoon, John Jones, chairman of the Adams-Morgan Day board of community activists, concluded that the festival "was looking great." Jones said organizers gave away $10,000 in grants this year to service groups in the neighborhood.

"We want to foster an example for the rest of the world about what neighborhood harmony is all about," Jones said. "It's about people working, living, worshiping and partying together and discovering each other as neighbors."