Royal watchers viewing the coronation will notice three members of Charles’ family missing from today’s festivities.

Harry’s wife, Meghan, the Duchess of Sussex, and their two children, Prince Archie and Princess Lilibet, did not attend the coronation.

Instead, they are home in California, where the family now lives full-time.

Today is Archie’s fourth birthday and Harry is expected to leave shortly after the coronation service to return home to his family.

As a non-working royal, Harry, who sat near his cousins Beatrice and Eugenie inside Westminster Abbey, did not join other members of the royal family in the procession back to Buckingham Palace.

Charles’ grandchildren George, Charlotte and Louis joined the Coronation Procession back to Buckingham Palace, riding in a carriage alongside their parents, William and Kate.

Charlotte, 8, and Louis, 5, sat by the carriage's windows, flanking their older brother George, 9. William and Kate are sitting together across from their children.

Other members of the royal family also traveling by carriage in the procession include Charles’ brother Edward, and his wife Sophie and their two children, Louise and James.

Absent from the procession are Charles’ youngest son, Harry, and his brother, Prince Andrew.

While not present for their coronation, U.S. President Joe Biden offered his congratulations to Charles and Camilla via Twitter.

"Congratulations to King Charles III and Queen Camilla on their Coronation," the president tweeted Saturday. "The enduring friendship between the U.S. and the U.K. is a source of strength for both our peoples. I am proud the First Lady is representing the United States for this historic occasion."

U.S. first lady Jill Biden, who attended the coronation in London, added her own message, tweeting: "The United States and the United Kingdom have a special relationship. It's an honor to represent the United States on this historic day at Westminster Abbey."

Charles selected his only sister, Princess Anne, to lead the procession from Westminster Abbey to Buckingham Palace.

Anne is following right behind Charles and Camilla on horseback as she leads a procession featuring 4,000 personnel, the largest military ceremonial operation of its kind since the queen’s coronation in 1953.

As Charles was crowned king, ABC News royal contributors weighed in on the moment.

Robert Jobson said he was feeling "deep pride in my country and the royal family and the clergy."

"Particularly a bit of relief for the king because I thought when the archbishop was trying to get that crown on his head, he was trying a little too hard," Jobson added, with a laugh.

Victoria Murphy commented on how the "mood really shifted."

"It was very solemn, it was quite tense, it felt very serious and then suddenly, it actually feels quite joyous now," Murphy said. "It feels like a moment of celebration."

Sir Peter Westmacott, who previously served as Charles' secretary, said he also felt "a sense of great pride" and is "delighted for my old boss."

"It's a wonderful moment of pageantry and the mixture of humility and service," Westmacott added, "but also the crowning of a monarch in a way that no other country in this world still does or indeed knows how to do as we do."

Ailsa Anderson, who previously served as press secretary to Charles' late mother, Queen Elizabeth II, described feeling "rather emotional about it all."

"However you prepare for something like this, to actually see it has made me swell with pride but also emotional and also proud of my former boss, the Archbishop of Canterbury, who has been faultless in this service," Anderson said. "I think this service is pretty stupendous."

Kristina Kyriacou, who previously served as the communications secretary to Charles and Camilla, said she was "absolutely overjoyed."

"I couldn't be happier. I feel very, very emotional," she added. "This is a king who has worked every second and every hour of the day for the past 60 years. You know, since his teens, he has absolutely worked in public service serving his mother, serving the nation and the commonwealth -- and he deserves this. And I hope everyone understands all the good that he has done and all the causes that he has championed."