LONDON (AP) -- With a smile that lit up TV screens around the world, Kate Middleton swept down the aisle to marry Prince William in a union expected to revitalize the British monarchy. Hundreds of thousands cheered as the royal couple rode an open carriage to Buckingham Palace.
With an estimated 2 billion people watching around the world, the couple managed to appear at times in their own private world Friday at Westminster Abbey. William whispered to Kate, who radiated contentment and joy, as they pledged their lives to one another with the simple words "I will."
The biggest secret of the day -- Middleton's wedding gown -- prompted swoons of admiration as she stepped out of a Rolls-Royce with her father. Against all odds, the sun broke through steely gray skies at that exact moment.
The ivory and white satin dress -- with its low neckline, high lace collar, long lacy sleeves and a train over 2-meters (yards) long -- was designed by Sarah Burton at Alexander McQueen. Middleton's hair was half-up, half-down and decorated with dramatic veil and a tiara on loan from Queen Elizabeth II.
"It's a dream," said Jennie Bond, a leading British monarchy expert and royal wedding consultant for The Associated Press. "It is a beautiful laced soft look which is extremely elegant. She looked stunning."
William, second-in-line to the throne after his father, Prince Charles, wore the scarlet tunic of an Irish Guards officer, sending a strong signal of support for the armed forces and reinforcing his new image as a dedicated military man. The couple's first royal wedding present came from the queen: the titles of duke and duchess of Cambridge.
Floods of well-wishers -- as well as some protesters -- packed central London, around Buckingham Palace, Westminster Abbey and other landmarks beginning at dawn, despite cool temperatures and the threat of rain. Cheers erupted as huge television screens began broadcasting at Trafalgar Square and Hyde Park.
"Will, it's not too late!" read one sign held aloft by an admirer dressed as a bride.
Maid of honor Pippa Middleton wore a simple column dress and naturally styled hair, while best man Prince Harry was dressed in formal military attire. The flower girls, in cream dresses with full skirts and flowers in their hair, walked down hand-in-hand with Pippa.
The iconic abbey was airy and calm, the long aisle leading to the altar lined with maple and hornbeam trees as light streamed in through the high arched windows. The soft green trees framed the couple against the red carpet as they walked down the aisle, having recited their vows without stumbling before Archbishop of Canterbury Rowan Williams.
The royal-couple smiled broadly as they were driven to Buckingham Palace in the open-topped State Laundau, a carriage built in 1902, escorted by four white horses and followed by scarlet-clad troops on horseback. The palace was holding two parties, one hosted by the queen for 650 guests, and an evening dinner dance for 300 close friends.
The queen and her husband have promised to go away for the evening, leaving the younger royals free to party the night away-- and Harry to make his best man's speech away from his octogenarian grandparents' ears.
Plumage of Amazonian variety filled the cavernous abbey as some 1,900 guests filed in, the vast majority of women in hats, some a full two feet (half a meter) across or high. Some looked like dinner plates, and one woman wore a bright red fascinator that resembled a flame licking her cheek. A BBC commentator noted there were some "very odd (fashion) choices" walking through the abbey door.
Most men, however, looked elegant and suave in long tails, some highlighted by formal plaid pants and vests. Others wore military uniforms.
The queen, of course, wore a soft yellow hat and coat dress, just like the bookies had predicted.
All the details -- the wedding dress, her hair, their titles, the romantic kiss on the balcony, the honeymoon -- were finally being answered. But the biggest question won't be resolved for years: Will this royal couple live happily ever after?
Will their union endure like that of William's grandparents -- Queen Elizabeth II and Prince Philip, now in its 64th year -- or crumble in a spectacular and mortifying fashion like that of his own parents, Prince Charles and Princess Diana?
Recent history augurs badly: The first marriages of three of the queen's four children ended in divorce. But William and Kate seem to glow with happiness in each other's company, and unlike Charles and Diana they've had eight years to figure out that they want to be together.
Still, the fate of their marriage depends on private matters impossible for the public to gauge, since any wedding is fundamentally about two people. Will their lives together, starting with such high hopes, be blessed by good fortune, children, good health, productive work?
Much will depend on whether 28-year-old William and 29-year-old Kate can summon the things every couple needs: patience, love, wit and wisdom. But they face the twin burdens of fame and scrutiny. Money, power, beauty -- it can all go wrong if not carefully nurtured.
These are the thorny issues upon which the fate of the monarchy rests, as the remarkable queen, now 85, inevitably ages and declines.
Hundreds of street parties were under way as Britons celebrated the heritage that makes them unique -- and overseas visitors come to witness traditions they've admired from afar.
Brenda Hunt-Stevenson, a 56-year-old retired teacher from Newfoundland, Canada, said there was only one thing on her mind. "I want to see that kiss on that balcony. That's going to clinch it for me. I don't care what Kate wears. She is beautiful anyway."
The celebration was British to the core, from the freshly polished horse-drawn carriages to the sausages and lager served at street parties. Some pubs opened early, offering beer and English breakfasts -- sausages, beans, toast, fried eggs and bacon.
The festivities reflected Britons' continuing fascination with the royal family, which despite its foibles remains a powerful symbol of unity and pride.
"It's very exciting," Prime Minister David Cameron said. "I went on to the mall last night and met some people sleeping on the streets. There's a sense of excitement that you can't really put a word to ... It's a chance to celebrate."
A number of famous people were left off the guest list, including President Barack Obama and Britain's last two prime ministers, Tony Blair and Gordon Brown of the Labour Party, which is not as strong a backer of the monarchy as the ruling Conservatives. That snub might resonate for years among Labour voters.
The royals fervently hope that a joyous union for William and Kate will rub out the squalid memories of his parents' embarrassing each other and the nation with confessions of adultery as their marriage tumbled toward divorce.
And there is no small irony in the sight of Americans waking up before dawn (on the East Coast) or staying up all night (West Coast) after their fellow countrymen fought so fiercely centuries ago to throw off the yoke of the British monarchy and proclaim a country in which all men are created equal.
Brenda Mordic, 61, from Columbus, Georgia, clutched a Union Jack with her friend Annette Adams, 66.
"We came for the excitement of everything," Mordic said. "We watched William grow up. I came for Prince Charles' wedding to Diana and I came for Princess Diana's funeral. We love royalty England and London."