It's arguably the biggest event in Britain since the wedding of Diana and Charles nearly 30 years ago.
Authorities say 5,000 police officers will be on patrol. Nearly 200 horses and 35 sniffer dogs will also be on guard.
They'll scour everything from the inside of the abbey to sewers and lamp posts, looking for anything suspicious. Authorities say they want nothing to compromise the event.
An estimated one million well-wishers are expected to descend on London to witness the royal wedding, and the British government estimates two billion viewers around the world will watch the nuptials live on TV.
About 1,900 people were invited to the April 29 Westminster Abbey ceremony.
Pub owner talks about royal invite
One of the 1,900 guests includes John Haley. He's the owner of the "Old Boot Inn," a pub that has been tucked away in the English village of Bucklebury for three centuries and is also reportedly Middleton's favorite pub.
"I don't care if next to Elton John or David Beckham, just to see Kate and her dad walk up the aisle, that's what I'm really looking forward to," Haley said [Watch video].
William, Kate's wedding to be more sensible
Prince William and Kate's wedding is being called the wedding of the century, but officials say it won't be as extravagant as the wedding of Prince Charles and Diana.
When Charles and Diana were married, they chose the much larger St. Paul's Cathedral for their state wedding in 1981. William and Kate's guest list is much smaller - 1,900 guests compared to 3,000 for Charles and Diana.
UCLA professor Dr. David Rodes expects a more sensible wedding and attributes it, in part, to a couple who really seem to know each other.
But can a royal wedding really be modest? Well, for one, Middleton will not arrive to the church in a horse drawn carriage [Watch video].
World media descends on London for nuptials
Media outlets from around the world are descending on London in time to bring the story of the prince and Kate home to their viewers.
"I think given all that's happened this year - we've had earthquakes, tsunamis, wars - people want some good news," said reporter Adrian Brown of Australia's Seven Network. "This is something the Brits still do quite well: pomp, pageantry, people in funny uniforms."
The paparazzi are in full force as well. [Watch video].
Southern California has strong ties to the United Kingdom
The lure of the West Coast in all its beauty is nothing new. Even back in the early years of Los Angeles' development, the Pacific Ocean attracted brilliant minds.
Three people in particular helped Los Angeles grow from a small town to the thriving metropolis that it is today.
In the early 1900s, William Mulholland was the head of Los Angeles Water and Power. He is credited with developing a series of aqueducts and dams that brought water and ultimately brought opportunity to develop in Southern California.
Griffith J. Griffith amassed a huge fortune during the 1880s in the mining industry. He eventually donated more than 3,000 acres to the city of Los Angeles, which is now Griffith Park. He also funded the building at the Griffith Park Observatory and the Greek Theater.
Born in Lancashire, England, John Parkinson moved to Los Angeles in 1894 and immediately went to work creating some of the city's most important and iconic buildings. In addition to designing Los Angeles City Hall, Memorial Coliseum and Union Station, Parkinson is also credited with building the city's first skyscraper and many of the buildings at the University of Southern California. [Watch video].
ABC7 anchors David Ono and Michelle Tuzee are in London for the royal wedding. Look for their live reports all week leading up to Friday's ceremony on Eyewitness News.
"Good Morning America" will have special royal wedding coverage Friday beginning at 1 a.m. PT.
Prince William and his best man Prince Harry will arrive at Westminster Abbey at 2:15 a.m. PT.
Queen Elizabeth II will arrive at the Abbey at 2:45 a.m. PT.
Kate Middleton will head to the Abbey from her hotel at 2:51 a.m. PT.
The actual wedding ceremony is set to take place 3 a.m. PT.
For the full wedding day timeline, click here.