Royal Wedding: Prince William and Kate Middleton Seal It With Balcony Kiss, Then Hit Palace to Party All Night

VIDEO: The Duke and Dutchess of Cambridge head to Buckingham
WATCH William and Catherine Leave Clarence House

The royal wedding at Westminster Abbey went off without a snag. Now it's time for selected guests to rock Buckingham Palace.

Thousands of people in the streets of London cheered Friday afternoon as the royal newlyweds, Prince William and Kate Middleton, made their way back from a brief rest to Buckingham Palace for a buffet dinner and all-night party with about 300 guests.

Middleton arrived at Buckingham Palace wearing a strapless white satin Sarah Burton evening gown with a circle skirt and diamante embroidered detail round the waist, according to The Associated Press. William wore a black tuxedo.

"I am glad the weather held off. We had a great day," Middleton told a photographer.

Nineteen rooms were set aside for the evening reception -- and Queen Elizabeth II and Prince Phillip handed over the palace for the post-wedding party that is expected to last until the morning. In fact, the queen was flown out of the palace by helicopter for a private weekend away.

The queen attended an earlier daytime lunch reception at Buckingham Palace for about 650 guests.

For the evening festivities, the throne room at Buckingham Palace was transformed into a disco with help from groom and bride's siblings, Prince Harry and Pippa Middleton. Harry, William's best man, was expected to toast his brother during the celebrations.

For those still standing Saturday morning, there will be bacon sandwiches and ice cream in the palace quad.

Watch a special 2-hour edition of "20/20" at 9 p.m. ET tonight to look at the big day, the night-time celebrations, and what's next for the happy couple, with Barbara Walters.

Earlier, William and Kate, holding each other's hands and gazing into one another's eyes, exchanged wedding vows in front of 1,900 guests. Kate became royalty, thrilling royal watchers around the world. William, 28, slipped a wedding band made of Welsh gold on the finger of the 29-year-old Middleton.

The bride, wearing a tiara loaned to her by the queen, appeared to marvel at the majesty of the nearly 1,000-year-old abbey, looking up and smiling as she and William sang along with their guests of friends, celebrities and royalty from other countries. Nearly 400 of the guests were close family and friends.

Explore Kate's Dress and Wedding Dresses of the House of Windsor

Before retreating to Clarence House for their rest, William and Kate sealed their royal wedding with two kisses on the balcony of Buckingham Palace as heart shaped balloons floated above cheering British subjects.

Stepping out onto the balcony, the couple was flanked by the wedding party, the royal family including Queen Elizabeth II, Prince Charles and the bride's family.

With hundreds of thousands gathered below them and millions watching expectantly on TV, the prince kissed his bride quickly. The crowd cheered and began chanting, "Kiss her again." The royal couple obliged with a second peck on the lips.

William and Kate looked up into the London sky as the Royal Air Force performed a flyover congratulating the couple. William is a member of the Royal Air Force.

The bells of Westminster Abbey began to ring as the couple rode triumphantly to the palace in an open carriage, waving to the cheering throngs.

Middleton told William in the carriage, "I'm so happy," according to a lip reader.

Earlier, with her face still veiled, Kate held onto her father and grinned as she walked down the aisle of the ornate cathedral to wed William, the heir to the British throne. A nervous Prince William chewed his lip as his mother, Princess Diana, used to do.

Prince William told Middleton, "You look beautiful" when she arrived at the altar of the church.

They exchanged smiles and William leaned over and winked at his father-in-law, Michael Middleton.

William reportedly cracked a joke saying, "We're supposed to have just a small family affair," according to a lip reader.

Watch the Royal Wedding

The wedding, watched by over 2 billion people worldwide, delighted the people of Britain. Crowds of at least million people lined the streets to watch the wedding, which is a national holiday. When the couple said their vows, the crowds let out a huge roar and popped champagne bottles.

Read the Royal Wedding Live Blog

Royal watchers enveloped in the Union Jack flag, waved and screamed outside of Buckingham Palace as orange balloons floated above them. The Band of Welsh Guards marched along the procession route in their red uniforms and black fur hats. Fans wore sparkly hats and masks of the married couple.

Royal Wedding Spectacular

The tough economic times seemed forgotten as the Archbishop of Canterbury presided over the meticulously planned wedding spectacle.

The newly titled Duchess of Cambridge wore a veil with her arms and shoulders covered in lace as she made her vows that turned the commoner bride into royalty. Pippa Middleton, Kate's sister, greeted her at the door of the abbey. She tended to Middleton's wedding dress, designed by Sarah Burton, a student of late British designer Alexander McQueen.

The arrival of Middleton's limousine was the final step in a carefully choreographed procession of celebrities, dignitaries and royalty to the historic church for the nuptials.

Watch a special 2-hour edition of "20/20" at 9 p.m. ET tonight for a look back at all the highlights from the royal wedding with Barbara Walters.

Queen Elizabeth II and Prince Charles, the grandmother and father of the groom, arrived at Westminster Abbey just moments before Middleton. Queen Elizabeth, wearing a bright yellow suit and hat, waved to the crowds as she and Prince Philip arrived to the site of the wedding.

The crowds who turned out for the event were jubilant, but at least 18 people have been arrested, Scotland Yard reported, and an abandoned car at the intersection of Grosvenor Gardens and Buckingham Palace Road was investigated by explosives officers, the BBC reported.

Middleton's mother, Carole, arrived with her son James. James was the only family member to speak during the wedding. He read a passage from the New Revised Standard Version Bible.

Prince William, resplendent in a crimson tunic of the Irish Guards and accompanied by his brother Prince Harry, saluted the guards as the car left Clarence House. William wore a blue sash with his red uniform. The sash represents the order of the garter, the most senior and the oldest British Order of Chivalry. It was founded in 1348.

"He's wearing the uniform of the Irish Guards because he is the colonel of the Irish Guards," said Robert Lacey, royal historian. "He's chosen to wear it because it's going to look very good on the day. Perhaps he knows it's going to match whatever his bride to be is going to wear as well."

Riding in a Bentley, William and Harry cheerfully greeted the excited crowds who lined their route to Westminster Abbey.

"I can hardly believe it actually. I sometimes still think of them as the 15 and 13 years olds that they were ... terrible naughty teenagers and here they are young men about to launch into a new chapter of William's life. How exciting," said Colleen Harris, former press secretary to the royal family.

Scotland Yard Tackles Security at Royal Wedding

After reaching the Abbey, the men walked down a red carpet into St. Edmund's Chapel, mingling with the wedding guests. Harry stopped and talked to the Spencer family, Princess Diana's family.

Male guests, including singer Elton John and soccer star David Beckham, sported elegant suits with tails or military uniforms while the ladies arrived wearing a riotous collection of elaborate hats. The hats are a fashion accessory ranging from giant brims in bright colors of pink, purple and yellow to tiny hats shaped like flowers perched on their foreheads. Others have sprigs and feathers sprouting from them. Mobile phones and cameras were banned at the wedding.

"The whole of the British upper lip kind of unbuttons with these hats," said Tina Brown, editor of Newsweek and the Daily Beast.

As the couple exited the abbey following their wedding, the bride curtsied to Queen Elizabeth and William bowed to his grandmother.

Hours after the ceremony and balcony appearance, the newlyweds surprised their fans by driving out of Buckingham Place in a convertible festooned with ribbons, trailing a tail of balloons and bearing the license plate "Ju5t Wed." Kate was still in her wedding gown as they drove to St. James Palace to rest before the evening party began.

The pageantry for the royal wedding of Prince William and Kate Middleton began today with Queen Elizabeth bestowing new titles on the couple, dubbing them the Duke and Duchess of Cambridge.

Along with becoming a duke, William also became Earl of Strathearn and Baron Carrickfergus, which means Middleton will become the Countess of Strathearn and Baroness Carrickfergus.

Carrickfergus is in the Northern Ireland county of Antim and has its own castle. Strathearn is in Scotland. Since William is also the Prince of Wales, his titles now encompass all the elements of Great Britain: England, Scotland, Wales and Northern Ireland.

Princes William and Harry spent Thursday night with their father, Prince Charles, having a private dinner. Queen Elizabeth greeted the foreign royals attending the wedding last night at the Mandarin Oriental Hotel in Hyde Park.

Scotland Yard beefed up security for the wedding, using 5,000 policemen -- both in uniform and undercover -- as close to the new royal couple as at the back of their carriage.

Scotland Yard officials said earlier this week that they were ready for anything that might disrupt the wedding.

"Any criminals attempting to disrupt it, be that in the guise of protest or otherwise, will be met by a robust, decisive, flexible and proportionate policing response," the London police officials said.

More than 1,500 soldiers, sailors and air crew are on duty to line the couple's procession route between Westminster Abbey and Buckingham Palace, just under a mile away. The couple plans to travel after the wedding from Westminster Abbey to Buckingham Palace in an open topped carriage, the 1902 State Landau.

ABC News' Linda Albin, Michael S. James, Aaron Katersky, Gabriel O'Rorke and Jean-Nicholas Fievet contributed to this report.

Watch a special 2-hour edition of "20/20" at 9 p.m. ET tonight to look at the big day, the night-time celebrations, and what's next for the happy couple, with Barbara Walters.