Charles III will be crowned king on Saturday in Britain's biggest ceremonial event for seven decades, a sumptuous display of pageantry dating back 1,000 years.
Charles succeeded his mother Queen Elizabeth when she died last September and at 74, he will become the oldest British monarch to have the 360-year-old St Edward's Crown placed on his head as he sits upon a 14th century throne at London's Westminster Abbey.
Watched by about 100 heads of state and dignitaries including U.S. first lady Jill Biden, Charles follows 40 predecessors in being crowned at the abbey - which has staged all the country's coronations since William the Conqueror back in 1066.
Ceremony Rooted in History
His second wife Camilla, 75, will also be crowned queen during the two-hour ceremony which, while rooted in history, will attempt to present a forward-looking monarchy and nation.
"No other country could put on such a dazzling display - the processions, the pageantry, the ceremonies, and street parties," Prime Minister Rishi Sunak said.
"It's a proud expression of our history, culture, and traditions. A vivid demonstration of the modern character of our country. And a cherished ritual through which a new era is born."
Despite Sunak's enthusiasm, the coronation is taking place amid a cost of living crisis and public scepticism, particularly among the young, about the role and relevance of the monarchy and questions about its finances.
Saturday's event will be on a smaller scale than that staged for Queen Elizabeth in 1953, but will still aim to be spectacular, featuring an array of historical regalia from golden orbs and bejewelled swords to a sceptre holding the world's largest colourless cut diamond.
After the service, Charles and Camilla will depart in the four-tonne Gold State Coach that was built for George III, the last king of Britain's American colonies, riding back to Buckingham Palace in a one-mile procession of 4,000 military personnel from 39 nations in ceremonial uniforms.
It will be the largest show of its kind in Britain since the coronation of Charles' mother. Thousands are expected to line the streets and millions will watch at home and across the globe.
Organisers have taken the "best bits" from previous coronations, jubilee celebrations and the late queen's funeral procession to prepare a spectacular event, said a Ministry of Defence spokesperson.
At the start of ceremonies, Charles and Camilla will travel from Buckingham Palace to the abbey in the modern Diamond State Jubilee Coach, with the service due to begin at 1000 GMT.
They will pass cheering crowds but also what anti-monarchists say will be the biggest protest mounted by republicans. More than 11,000 police will be on duty ready to stamp out any attempted disruption.
Once at the abbey, much of the ceremony will feature elements that Charles' forebears right back to King Edgar in 973 would recognise, officials said. Handel's coronation anthem "Zadok The Priest" will be sung as it has at every coronation since 1727.
But there will be new elements, including an anthem composed by Andrew Lloyd Webber, famed for his West End and Broadway theatre shows, and a gospel choir.
It is a Christian service but there will be an "unprecedented" greeting from leaders of other faiths and Charles's grandson Prince George and the grandchildren of Camilla will act as pages.
However, there will be no formal role for either Charles' younger son Prince Harry, after his high-profile falling out with his family, or his brother Prince Andrew, who was forced to quit royal duties because of his friendship with late U.S. financier Jeffrey Epstein, a convicted sex offender.
Charles will swear oaths to govern justly and uphold the Church of England - of which he is the titular head - before the most sacred part of the ceremony when he is anointed on his hands, head and breast by Archbishop of Canterbury Justin Welby with holy oil consecrated in Jerusalem.
After Charles is presented with symbolic regalia, Welby will place the St Edward's Crown on his head and the congregation will cry "God save the King".
His eldest son and heir Prince William will then pay homage, kneeling before his father, placing his hands between those of the king and pledging his loyalty as "your liege man of life and limb".
Welby will call for all those in the abbey and across the nation to swear allegiance to Charles - a new element of the coronation, replacing the homage that was traditionally sworn by senior dukes and peers of the realm.
However, that has caused controversy with anti-monarchist group Republic calling it offensive, forcing Welby to clarify it is an invitation not a command.
After returning to Buckingham Palace, the royals will make a traditional appearance on the balcony, with a fly-past by military aircraft.
Also in traditional British fashion, the weather in London could feature heavy bursts of rain, forecasters said, which could mean a slimmed down or even cancelled fly-past.
Celebrations will continue on Sunday with nationwide street parties and a concert at the king's Windsor Castle home, and on Monday when thousands of organisations are taking part in volunteering projects.
Queen Elizabeth said in a television documentary five years ago that her coronation marked the real beginning of her life as sovereign.
"It is sort of a pageant of chivalry and old-fashioned way of doing things," she said.