The lines have never been so long at Westminster Abbey, and the masses are there for one reason: William and Kate.
Just days out from the royal wedding, the crowds swelter in April temperatures of 26C and fork out the £16 ($33) charge to enter.
US tourist Patricia Cormack, 34, travelling with her husband Adam, said her homeland was going crazy for the wedding.
Most of the teachers at the Boston school she works at will take a day off to watch the proceedings. "It's all over the TV, people can't get enough of it," Ms Cormack said.
"We came here on Monday but the lines were even bigger so we went to Windsor Castle instead. We're here for a week and we're not leaving until we see where the wedding is happening."
Australian Lucy Donlan, 24, came straight from Heathrow Airport after a 24-hour flight from Sydney.
"My friends want to watch the wedding on a big screen at Clapham but I want to be right in the thick of it. I think I'm the only one that's really interested."
Workmen can be seen busy on rooftops and balconies around the abbey, prime locations to watch the royals arrive in their coaches and vehicles from the Royal Mews.
After the service, the newlyweds will be carried by open-topped horse-drawn carriage back to Buckingham Palace.
The top spot is undoubtedly the Sanctuary beside the abbey. Revellers can reportedly hire out the nine rooms and four balconies for £100,000 ($206,000).
The neighbouring Iranian Oil Company is hiring out two offices for the same amount. At the other extreme, the Methodist Central Hall, opposite the abbey, will host a £60-a-head champagne breakfast for 500 guests.
The procession back to the palace will be led by a Sovereign's Escort for the Queen and Prince Philip and a Captain's Escort for the bride and groom. It will continue along the east side of Parliament Square, opposite Big Ben and Parliament. Running north from the square towards Trafalgar Square is Whitehall, the hub of Government buildings.
The Red Lion pub, a regular haunt for politicians and journalists, plans to stay open on the day, as does the neighbouring Snappy Snaps photo shop. Shopkeeper Mayu Manoharan, 24, has already sold out of £10 William and Kate mugs delivered two days ago.
"It's going to be so busy and there'll be barriers along the street but I'll try and get to the front to have a look."
At Downing Street, the official residence of the Prime Minster, hundreds of tourists surround the gates. And a few metres away is the Toomey family's souvenir stand, which they have been running since 1948.
The stall is usually packed up at the end of each day but with hundreds of people expected to camp along the route the night before to ensure a good viewing point, Ricky and Sue Toomey, both 64, will stay open all night.
Their son, also named Ricky, has come home from Perth in Western Australia for the royal wedding and to take over from his tired parents on the morning.
"But I think they'll probably stick around though," he said.
"They won't be able to tear themselves away from all the excitement."
Mr Toomey, 37, said they had probably seen a 30 per cent increase in sales in the past few weeks with the inclusion of William and Kate tea-towels, mugs and magnets.
In exclusive Belgravia, a group of eight nannies, working for bosses in the area, were having a garden party with their children.
They had a Union flag, plates and serviettes, and had hung up ensigns in the trees above them.
Leah Pihl, from Sweden, will have the day off next Friday, and may come back. "We decided to have a garden party because of the royal wedding, and it's the Easter holidays."
The park near the exclusive area runs alongside The Mall, a road red in colour to give the appearance of a red carpet leading up to the palace.
It was created as a ceremonial route in the early 20th century and is closed to traffic on Sundays and public holidays.
Speakers have been set up along the route to play the service to the thousands after the family have left the palace. There will also be screens at Hyde Park and Trafalgar Square.
Thousands of police and soldiers will line the procession route.
Passing Clarence House, William and Harry's childhood home, the procession will eventually reach Queen Victoria memorial before entering the palace.
The newlyweds and their families will emerge on the balcony soon after and wave to the millions watching on television around the world.
And there, the kiss that everyone is waiting for will be delivered.