Fears of technological disaster and apocalyptic violence gave way to giddy global celebration yesterday as the first day of the long-anticipated new year swept peacefully westward around the planet and across the United States.

The Year 2000--for generations a symbol of the distant, dazzling or daunting future--was greeted with joy and relief by crowds from Auckland to London to Washington and New York. On an unseasonably balmy evening, more than 300,000 people thronged the Mall despite tight security measures, while perhaps as many as 3 million crowded around Times Square in Manhattan.

Spectacular fireworks illuminated some of the world's most famous sites--the pyramids, the Parthenon, the Eiffel Tower, Big Ben and the Washington Monument. Never was so much exploded for friendly reasons.

As midnight moved through the Greenwich Meridian--a crucial time standard for scientists, armies, pilots and other computer users around the world--there were no serious disruptions anywhere. Lights, water, phone service and bank machines met midnight without a hiccup along the East Coast. Computers did some funny things--the date on the screen as this story was being written read "1/1/10"--but most continued to function.

This overwhelmingly successful cure of the Y2K bug--an effort that stretched over several years and cost perhaps $500 billion--ranks among the world's greatest technological mobilizations in peacetime.

It was a symbolic moment, but human beings live by symbolism. The date change felt like a summing up--and not only because it concluded months of millennial listmaking and reflection. Americans looked back on a century that dawned on family farms lit by kerosene. There were 8,000 cars in the United States and 144 miles of surfaced roads. World wars, antibiotics, airplanes, relativity, radio, television, computers--all were unknown. It came to be known as the American Century.

"If the story of the 20th century is the triumph of freedom, what will the story of the 21st century be?" President Clinton asked during a brief speech at the Lincoln Memorial in the last minutes of the year. "Let it be the triumph of freedom wisely used."

Clinton wore a jet-black tuxedo, fresh from a lavish White House dinner to mark the occasion. Huge floodlights turned the Washington midnight to day. "We know the sun will always rise on America as long as each new generation lights the fire of freedom," Clinton said. As he finished his remarks, a representative group of Americans ignited a chain of fire that sprinted across the Reflecting Pool and climbed the Washington Monument one second at a time.

Year 2000 arrived just as the obelisk was crowned in light.

Times Square was shoulder-to-shoulder for more than 20 city blocks, and the chattering masses spoke languages from around the world. Manhole covers were welded shut and thousands of police officers patrolled the scene, each carrying a hand-held light in case of blackout. Some were equipped with anthrax antidote. But by midnight, police reported only six arrests, including a man with a gun in his car.

The traditional ball--only bigger and glitzier than ever before--dropped down a pole atop the building at One Times Square at the stroke of midnight.

A laser light show on Chicago's Loop followed a huge dinner at which citizens of nearly 200 countries and territories gathered to celebrate.

Live television images, seen by an audience of perhaps 1 billion, skipped lightly about the world, showcasing a communications revolution that has run from Gutenberg to Intelsat. Even more striking, perhaps, was the sheer extent of the celebrations--a fact that emphasized the centuries-long rise to dominance of the culturally Christian, capitalist West.

The Chinese New Year arrives in February, yet fires blazed along the Great Wall as Premier Jiang Zemin hailed the new millennium of Pope Gregory's 16th-century calendar. In Bangladesh, where the Muslim calendar says it is 1420, authorities struggled to keep alcohol-soaked parties from spilling into the streets. The New Year's celebration in New Delhi drew a huge crowd, even though the Hindu calendar pegs the current year at 2056.

On the Pacific island of Tonga, King Tafa'ahau Tupou IV and 10,000 of his subjects greeted the new year singing music by Handel.

That's not to say the moment obliterated cultural differences. Devout Muslims in Egypt and elsewhere avoided ceremonies in order to keep the holy season of Ramadan, and the streets of Jerusalem were largely silent. Rabbis had warned Jews to avoid all celebrations because New Year's fell on the Sabbath--in the Jewish Year 5760. Christian pilgrims camped on the Mount of Olives where, according to Scripture, Jesus will someday return to Earth.

Worries over possible computer failures and threats of terrorist attacks lent gravity to the approaching midnight. As 2000 reached such major cities as Sydney and Tokyo without significant breakdowns--and as it passed into Russia and China without a nuclear catastrophe--the cloud of doom began to dissipate. Federal Aviation Administrator Jane Garvey was aloft, as promised, when flight control computers made the switch; her plane landed in Dallas without incident.

Even relatively optimistic experts had expected major problems in Africa and other less-developed areas, but the critical hour reached Lagos, Nigeria--one likely trouble spot--uneventfully.

Scattered breakdowns occurred around the world--a failure of nonessential computers at two Japanese nuclear power plants; a confused microprocessor at a Wisconsin electrical utility--and more are still expected in coming weeks as glitches surface. Many computer systems were shut off for the weekend, from Chinese bank machines to seaports around the world, and problems may reveal themselves when the systems are turned back on.

"I think one of the questions you've begun to see surface a little around the edges is, 'Well, has this been all hype?' " said John Koskinen, head of the U.S. effort to stop the millennium bug. "I think we should not underestimate the nature of the problem that was originally there."

But as the day unrolled at Koskinen's headquarters in Washington, things were so slow that staff members popped the film "Apocalypse Now" into the briefing room's video system to kill time.

The old year did not go quietly. Russian President Boris Yeltsin stunned his country and surprised the U.S. government by announcing his resignation yesterday. He asked the forgiveness of the Russian people for the hardships of recent years. Prime Minister Vladimir Putin became acting president.

More than 150 hostages were freed after seven days trapped by hijackers aboard an Indian Airlines jet in Afghanistan. In exchange, India released three Muslim militants. The hijackers were allowed to drive away and seek asylum, though Taliban militiamen trailed close behind them.

As scheduled, the Panama Canal passed from U.S. to Panamanian control.

Purists argued, correctly, that the true new millennium is still a year away. The Gregorian calendar began with Year 1, and so 2,000 years later will be 2001. But that argument fell to the power of the zeros. And to another simple power: The thousand years that began with a 1--from 1000 to 1999--have ended; a thousand years starting with 2 have begun.

Where did it begin? That's a matter of some dispute. Fiji is the island nation closest to the 180th meridian--the International Date Line. But another Pacific island group, Kiribati, passed a law relocating itself two time zones westward in an effort to claim the distinction and, for good measure, renamed part of itself Millennium Island.

The USS Topeka, a 360-foot nuclear attack submarine, parked itself astraddle the date line, 400 feet below the surface, its port side in one year and its starboard in the other. "It's better than Times Square," said Lt. Michael Bratton of Little Rock.

From there, the new year moved through New Zealand into Australia and Japan, where cell phones began having trouble making international connections. Prime Minister Keizo Obuchi attributed the problem to "too many 'Happy New Year' calls."

Next into Siberian Russia. Fears of Y2K problems were amplified in Russia, with its impoverished government and frail infrastructure. But officials said the nuclear reactor at Bilibinsk, the first one tested by the date change, kept humming as normal. At 4 p.m. EST, as Washingtonians were streaming toward the Lincoln Memorial for the evening festivities, midnight struck in Moscow and a crowded Red Square erupted in cheers, glowed with fireworks--and continued to function as before.

Throughout the day, at Peterson Air Force Base in Colorado, U.S. and Russian military experts sat together monitoring nuclear warning systems to avoid an accidental missile launch--a bit of cooperation unthinkable in the Cold War. While they watched, three Russian Scud missiles were fired into Chechnya as part of Moscow's continuing war with the rebellious region.

Two people were killed and many more injured in Manila when Filipino soldiers and police officers began boisterously firing their weapons into the air at the stroke of midnight.

When the moment reached Beijing's enormous Tiananmen Square, Premier Jiang--flanked by members of the last remaining communist government of global importance--ignited an eternal flame and promised that the next century will bring unification with Taiwan and a "great rejuvenation" of China. In 2000, even Chinese communism is not what it used to be: The holiday was marked in Shanghai by all-night shopping sprees.

The months leading up to the calendar change were filled with hype, stock-taking and dread. Every magazine, TV network, newspaper and Web site seemed to have its own rankings of 100 best, 10 worst, all-time greatest--from Time's Person of the Century (Albert Einstein) to MTV's No. 1 video (Michael Jackson's "Thriller"). There were harrowing tales of computer experts holed up in remote redoubts, stockpiling food for the Y2K disaster, and reports of millennial sects preparing for the end of the world. In the waning weeks of the year, Israel expelled an apocalyptic Christian sect from Jerusalem, fearing that the group might resort to violence in hopes of bringing on the Second Coming.

In mid-December, an Algerian man was arrested in Port Angeles, Wash., trying to enter the country from Canada. His car was full of bombmaking materials. A nationwide investigation led to further arrests, and FBI officials hoped they had prevented a terrorist attack on U.S. New Year's celebrations. Nevertheless, Seattle Mayor Paul Schell canceled that city's main gathering at the giant Space Needle.

Other cities planned to deploy record numbers of police officers to keep the peace and watch for trouble. One thousand National Guard members were placed on call at the D.C. Armory.

Yet as the day drew near, a distinct lassitude set in. There were reports of surplus champagne and lobsters, discounted hotel rooms, and parties canceled for lack of interest. Two big events planned for Washington--one at the Ronald Reagan Building, another at MCI Center--were scrapped because of slow ticket sales.

Then the time finally came, and crowds were large and mostly peaceable. Bells rang in Scandinavia, children sang in Greece, reggae rhythms pulsed on South Pacific beaches. High-priced tickets to fancy shindigs went unsold, but around the world, ordinary people hit the streets, eager to give a cheer or to kiss somebody.

It was true most places--from Fiji, where swank parties went half-filled but the sands were teeming with dancers, to Las Vegas, where hotel rooms that would cost a person $2,000 if reserved a year ago were going for $299. A quarter-million people were expected along the Vegas Strip.

The throngs were rewarded with some of the most elaborate and incandescent displays the world has seen. Cities seemed bent on out-blazing one another. Sydney bathed its famous opera house in fountains of stars; in Egypt, the great pyramids glowed; from inside the Parthenon overlooking Athens came a dazzling blue light; the Eiffel Tower radiated fire; lights at the Brandenburg Gate raked the sky. In London, four miles of the River Thames ran through a tunnel of pyrotechnics.

In Rome, home of the calendar, St. Peter's Square was jammed with people and bright as day when Pope John Paul II stepped onto his balcony to mark the moment. "What suffering, what dramatic events!" said the pope of the passing century. "But, also, what incredible achievements!"

In Bethlehem, zero point of Christian time, there were more fireworks and dancing in the streets.

Midnight moved steadily west. And six hours later the sun rose around the globe, as it has for all earthly time, only now in many minds something had ended and something slightly different had begun.

Today's babies won't think twice about 2000.

For them, those previous thousand years will be a large, completed parcel. And the parcel is already imperceptibly receding from them, bearing so much--the Crusades, the Ming Dynasty, the shogun, Mali gold, the Renaissance, Shakespeare, the steam engine and the Holocaust--into another, ever more remote, time.

Contributing to this report were correspondents Stephen Buckley in Rio de Janeiro, William Drozdiak in Berlin, Paul Duggan in Austin, Peter Finn in Warsaw, Lee Hockstader in Jerusalem, Michael Laris and John Pomfret in Beijing, Colum Lynch in New York, T.R. Reid in Greenwich, England, Keith B. Richburg in Fiji, Howard Schneider in Giza, Egypt, R. Jeffrey Smith in Rome, Doug Struck in Tokyo, Roberto Suro at the Pentagon, Charles Trueheart and Anne Swardson in Paris and Daniel Williams in Moscow. Special correspondents Sarah Delaney in Rome, Liz Garone in San Francisco, Mike O'Connor in Jerusalem and Khiota Therrien in Seattle also contributed.

CAPTION: The first couple wave to crowd at a celebration for children at the Ronald Reagan Building. At right is Secretary of State Madeleine K. Albright.

CAPTION: People walk along the Great Wall of China, which was lit up for New Year's, shortly after midnight, as East Asia welcomed the first of 1,000 years that will start with a 2.

CAPTION: Fireworks kick off 2000 on the Mall. Pyrotechnics dominated the global festivities from Sydney Harbor to the pyramids of Egypt to the Eiffel Tower to Times Square.