London - Each step has been rehearsed, each flower meticulously arranged, the aisle of Westminster Abbey transformed into a flowering green avenue of trees.
As Kate Middleton and best man Prince Harry had a final run-through inside the abbey where she will marry Prince William on Friday, a growing throng of curious tourists, dedicated monarchists, souvenir vendors, William-watchers and Harry-hunters turned the Union Jack-bedecked streets outside the iconic landmark into a scene of festive chaos.
"It's a once-in-a-lifetime thing. Not many kings-to-be are going to be married anytime soon," said 26-year-old Sarah White of London, camping out across from the abbey with her sister, Liz.
"Everyone's making friends and are in good spirits - or at least will be until tomorrow [Friday]."
The only clouds on the horizon: the threat of rain and the intrusion of politics, as the British government decided to revoke an invitation to Syria's ambassador to condemn his government's crackdown on protesters that has left hundreds dead.
Friday's ceremony has been planned like a military operation - which, in part, it is.
Over 1 500 soldiers, sailors and air crew will be on ceremonial duty to line the couple's procession route between the abbey and Buckingham Palace, just under 1.6km away.
An additional 5 000 uniformed and undercover police will be alert for threats from Irish dissident terrorists, Muslim extremists, anti-monarchists, royal obsessives and drunken hooligans.
The royal wedding ceremony will offer pomp and circumstance on a grand scale, starting with a global guest list of 1 900 that includes kings and queens, sports stars, music royalty, university chums, Royal Air Force pilots and charity workers as well as friends and family.
Royal carriages drawn by mounted troops of the Household Calvary will be rolling to the palace in a sweeping procession under fluttering rows of bold red, white and blue Union Jacks. Hundreds of thousands are expected to line the parade route, which has been scrubbed down by street cleaners.
Westminster Abbey itself has been remade into a blooming forest, with six field maples and two hornbeams lining the aisle leading up to the altar.
Royal officials said William and Kate have been intimately involved in planning their wedding day, from the music at the ceremony to the flowers to the cake - in fact, two cakes - that will be served to the guests.
Kate opted for a traditional white-iced fruitcake while William made sure that was accompanied by his childhood favourite, a chocolate biscuit cake.
Much at stake
Britain has not seen a royal celebration on this scale since 1981, when Prince Charles married Lady Diana Spencer at St Paul's Cathedral.
Much is at stake for the royal family, who hope the latest royal match bolsters the Windsor dynasty and smooths over memories of a series of failed royal marriages, including those of Charles and Diana, Prince Andrew and Sarah Ferguson and Princess Anne and Mark Phillips.
Despite knowing how Charles and Diana's fairy-tale ended - in a 1996 divorce, after embarrassing admissions of adultery on both sides - most Britons feel an outpouring of goodwill for his son William and fiancée Kate.
The British government also hopes the wedding will lift people's spirits during a period of tough austerity measures.
The Conservative-led government is cutting £81bn in spending through 2015, slashing hundreds of thousands of government jobs and sharply hiking tuition fees.
Excitement built on Thursday, as the crowd of die-hard fans camped out in tents and sleeping bags swelled near the 1 000-year-old abbey.
Among them was India Marlow-Prince, a 17-year-old from London who was picnicking with friends. The trio painted their faces with the Union Jack and wore tiaras and matching hot pink T-shirts with the homemade slogan "Will and Kate forever."
"She is the Diana of our generation. And Wills is a babe," Marlow-Prince said. "We are a little annoyed at her for taking him, but there's always Harry."
Prince Charles' wife Camilla, Duchess of Cornwall, delighted royal fans by emerging from her residence nearby for a walkabout.
"We're all ready for tomorrow [Friday]," she said. "It's wonderful and we're all very excited."
More royal-watchers gathered nearby outside the five-star Goring Hotel, where Kate and her family are spending her last night as a single woman. A canopy was erected over the entrance to block onlookers from catching sight of Kate when she emerges in her wedding dress Friday morning.
The dress has been the best-kept secret of this very public event. Its designer remains unconfirmed, and hundreds of millions of TV viewers will see it for the first time when Middleton steps out of her Rolls-Royce at the abbey. Her husband-to-be will see it a few minutes later, when she makes her entrance.
After Friday morning's ceremony, the couple will travel to the palace and emerge onto the balcony for a precisely timed kiss - at 13:25 - followed by a fly-past of military aircraft.
Then the party starts.
About 650 people are invited to a luncheon at Buckingham Palace with the queen, and later that night 300 close friends and family will attend a black-tie evening bash.
The palace says Queen Elizabeth II and her husband Prince Philip planned to go away for the evening, leaving the younger royals free to party unfettered - and Harry to make his best man's speech away from his octogenarian grandparents' ears.
British singer Ellie Goulding, 24, is reportedly going to perform, and rumours have it that Harry has even planned a morning breakfast for those with the stamina to dance all night.
Hundreds of thousands of people across the country will celebrate as well, for the day has been declared a public holiday.
Over 5 500 official street parties are planned, including one by the anti-monarchist group Republic and another on Downing Street, home to Prime Minister David Cameron.
Cameron told CBS the wedding will bring "happiness and joy and light relief after some difficult times".
In William and Kate's wedding programme, released on Thursday and on sale for £2, the couple said they have been deeply touched by the outpouring of affection toward them.
"We are both so delighted that you are able to join us in celebrating what we hope will be one of the happiest days of our lives," they wrote. "The affection shown to us by so many people during our engagement has been incredibly moving, and has touched us both deeply."
They also released a new photograph by celebrity photographer Mario Testino - a warm black-and-white image showing them with broad smiles and sparkling teeth.
Middleton will not promise to "obey" her new husband in her vows but instead to "love, comfort, honour and keep" him.
She will walk up the aisle to the sounds of "I was glad," the anthem setting of Psalm 122 composed by Sir Charles Hubert Hastings Parry for the coronation of King Edward VII in 1902. The anthem was also sung at the 1981 wedding of William's parents.
But as wedding excitement heated up, the weather in London cooled down. Royal wedding fans may want to pack extra umbrellas.
Gray skies are forecast for Friday, with a 30% chance of rain at the time of the ceremony, the Meteorological Office said. Some sunshine might break through in the morning, with temperatures rising to about 19°C.