King Charles III coronation recap: The biggest moments

Charles and Camilla’s ride to Westminster Abbey is the Diamond Jubilee State Coach, which was created for Charles’ mother in 2012.

The air-conditioned coach is led by six Windsor Grey horses as it travels down The Mall, through Admiralty Arch, down Whitehall and along Parliament Street, around Parliament Square to Westminster Abbey.

This procession, called the King’s Procession, is a scaled-down version of what we’ll see when Charles and Camilla return to Buckingham Palace after the coronation service.

Music superstar Katy Perry is among the celebrities attending Charles' and Camilla's coronation.

Perry, who is performing at Sunday's coronation concert, is wearing a purple skirt suit complemented by a purple hat.

Other celebrities in attendance at Westminster Abbey include Emma Thompson, Lionel Richie and U.S. first lady Dr. Jill Biden.

Charles and Camilla, the Queen Consort, made their first appearance on their history-making day, traveling from Clarence House to Buckingham Palace.

The king and queen were photographed traveling by car to the palace.

London's Metropolitan Police Service announced via Twitter that its officers "have made a number of arrests in the area of Carlton House Terrace," which is just west of Trafalgar Square.

"The individuals have been held on suspicion of breaching the peace," police added.

Earlier, officers also arrested four people in the area of St. Martin's Lane, which is just north of Trafalgar Square.

"They were held on suspicion of conspiracy to cause public nuisance," police said. "We seized lock-on devices."

An additional three people were arrested in the area of Wellington Arch, which is situated between the corners of Hyde Park and Green Park, just west of Buckingham Palace.

"They were held on suspicion of possessing articles to cause criminal damage," police said.

Hundreds of anti-monarchy protesters are gathered in Trafalgar Square.