The coronation of King Charles III and his wife Camilla as queen on Saturday is the centrepiece of a weekend of events to mark the occasion.
The day begins at 10:20 am (0920 GMT) with the “King’s Procession” – a two-kilometre (1.3-mile) journey from Buckingham Palace in central London to Westminster Abbey.
The couple will travel in the Diamond Jubilee State Coach, drawn by six Windsor Grey horses, and escorted by members of the king’s bodyguard, the Household Cavalry.
They will arrive for the start of the ceremony at 11:00 am.
Charles will be crowned at 12:00 pm and the service, led by the highest-ranking cleric in the Church of England, Archbishop of Canterbury Justin Welby, ends at 1:00 pm.
About 2,300 people, from foreign leaders and royalty to elected officials and civil society representatives, will be inside the abbey.
The ceremony has largely remained the same for more than 1,000 years.
The king will first be presented to the congregation, who respond with shouts of “God Save King Charles!”. Trumpets sound after each recognition.
The Archbishop of Canterbury will administer the Coronation Oath – a legal obligation – framed in the form of questions to the monarch.
The wording has varied over the centuries.
Charles will respond to the questions with his hand on the Bible and then say: “The things which I have here before promised I will perform and keep. So help me God”.
He will also take a separate Accession Declaration Oath in which the monarch declares to be a “faithful protestant”.
The sovereign, sitting in King Edward’s Chair (the Coronation Chair) under a canopy, is then “anointed, blessed and consecrated” by the archbishop.
Consecrated oil is poured from a gold ampulla and administered using a 12th-century silver-gilt spoon that is the oldest artefact among the Crown Jewels.
The anointing will be “the only part of the ceremony the public will not see”, Welby has said.
The Coronation Chair was made in 1300. Underneath it is the “Stone of Destiny”, an ancient symbol of Scotland’s monarchy seized by King Edward I.
After receiving the sovereign’s orb and sceptres, which represent their spiritual and temporal powers, the monarch has the St Edward’s Crown placed on their head.
The solid gold crown set with gemstones, such as rubies and sapphires, is only worn when the monarch is crowned.
The monarch moves to the throne.
Traditionally, the archbishop, the heir to the throne followed by royal dukes and hereditary peerage kneel and swear allegiance.
But heir apparent Prince William will be the only royal duke to pay homage to Charles. William is Duke of Cornwall as well as Prince of Wales.
And replacing the homage of peers, the Archbishop of Canterbury will invite all people from wherever they are watching or listening to pledge allegiance to the new sovereign, a historic first.
Camilla will then be crowned separately in a similar but simpler ceremony.
The king and queen will return to Buckingham Palace in the Gold State Coach in a larger ceremonial “Coronation Procession”.
The coach, first used in 1762, weighs four tonnes and will be drawn by eight Windsor Greys, at walking pace.
They will be joined by other members of the royal family. Some 7,000 British and Commonwealth troops in full regalia are taking part in the parades.
At the palace, they will appear on the balcony at about 2:15 pm to greet the crowd and watch a Royal Air Force fly-past.
On Sunday, neighbourhood street parties – “The Big Coronation Lunch” – will be held across the UK.
At 8:00 pm, Windsor Castle, west of London, hosts some 10,000 people at a Coronation Concert, featuring artists including Katy Perry, Lionel Richie, Take That and Andrea Bocelli.
Monday May 8 has been declared a public holiday. The royal family has called on Britons to do voluntary work in their communities.