King Charles III is crowned by the archbishop of Canterbury during his coronation ceremony in Westminster Abbey, London [Jonathan Brad via Reuters]
King Charles III is crowned by the archbishop of Canterbury during his coronation ceremony in Westminster Abbey, London [Jonathan Brad via Reuters]

King Charles III has been crowned at Westminster Abbey in a ceremony built on ancient traditions at a time when the British monarchy faces an uncertain future.

Trumpets sounded inside the medieval abbey and the congregation shouted “God save King Charles” as the ceremony began on Saturday in front of more than 2,000 guests, including world leaders, aristocrats and celebrities.

Outside, thousands of troops, tens of thousands of spectators, and a smattering of protesters converged along a route the king travelled from Buckingham Palace in a gilt-trimmed, horse-drawn carriage.

It was the final leg of a seven-decade journey for Charles from heir to monarch.

To the royal family and government, the occasion — code-named Operation Golden Orb — was a display of heritage, tradition and spectacle unmatched around the world.

The rite was expected to be watched by millions, and many greeted the day with apathy.

Some even met it with disdain. Republican protesters gathered outside to holler “Not my king” of an institution they say stands for privilege and inequality in a country of deepening poverty and fraying social ties. A handful were arrested.

King Charles III during his coronation ceremony in Westminster Abbey, London.
King Charles III during his coronation ceremony in Westminster Abbey, London. [Yui Mok via Reuters]
King Charles III, left, stands next to Archbishop of Canterbury Justin Welby during his coronation ceremony.
King Charles III, left, stands next to Archbishop of Canterbury Justin Welby during his coronation ceremony. [Aaron Chown/Pool/AP Photo]
Archbishop of Canterbury Justin Welby, centre right, attends the coronation ceremony of Britain's King Charles III.
Archbishop of Canterbury Justin Welby, centre right, attends the coronation ceremony of Britain’s King Charles III. [Aaron Chown/Pool/AP Photo]
Britain's King Charles III arrives for his coronation at Westminster Abbey in London.
Britain’s King Charles III arrives for his coronation at Westminster Abbey in London. [Andrew Matthews/Pool/AP Photo]
Britain's King Charles III is seen through the window of the Diamond Jubilee State Coach as he leaves Buckingham Palace with Camilla, the queen consort, for the coronation ceremony.
Britain’s King Charles III is seen through the window of the Diamond Jubilee State Coach as he leaves Buckingham Palace with Camilla, the queen consort, for the coronation ceremony. [Frank Augstein/AP Photo]
Britain's Prince William and Kate, princess of Wales, arrive at the coronation of King Charles III.
Britain’s Prince William and Catherine, Princess of Wales, arrive at the coronation of King Charles III. [Phil Noble/Pool/AP Photo]
Standard bearers and members of the military in Parliament Square ahead of the coronation ceremony of King Charles III.
Standard bearers and members of the military in Parliament Square ahead of the coronation ceremony of King Charles III. [Jane Barlow/Pool/AP Photo]
Foot Guards march at the Mall in preparation for the coronation ceremony for Britain's King Charles III in London.
Foot Guards march at the Mall in preparation for the coronation ceremony for Britain’s King Charles III in London. [Vadim Ghirda/AP Photo]
Police ride on horseback at the Mall before the coronation of Britain's King Charles III in London.
Police ride on horseback at the Mall before the coronation of Britain’s King Charles III in London. [Jon Super/Pool/AP Photo]
Troops march outside the Palace of Westminster ahead of King Charles III's coronation ceremony in London.
Troops march outside the Palace of Westminster ahead of King Charles III’s coronation ceremony in London. [Markus Schreiber/AP Photo]
Workers prepare the balcony of Buckingham Palace ahead of King Charles III's coronation ceremony in London.
Workers prepare the balcony of Buckingham Palace ahead of King Charles III’s coronation ceremony in London. [Petr David Josek/AP Photo]
People gather ahead of the coronation of Britain's King Charles III in London.
People gather ahead of the coronation of Britain’s King Charles III in London. [Piroschka van de Wouw/Pool/AP Photo]
A protester holds up a placard reading 'Not My King' in Trafalgar Square close to where Britain's King Charles III and Queen Consort Camilla will be crowned at Westminster Abbey in central London.
A protester holds up a placard reading ‘Not My King’ in Trafalgar Square close to where Britain’s King Charles III and Queen Consort Camilla will be crowned at Westminster Abbey in central London. [Sebastien Bozon/Pool/AP Photo]
Protesters wave 'Not My King' signs near to the 'King's Procession', a journey of 2km (1.2 miles) from Buckingham Palace to Westminster Abbey in central London ahead of the coronations.
Protesters wave ‘Not My King’ signs near to the ‘King’s Procession’, a journey of 2km (1.2 miles) from Buckingham Palace to Westminster Abbey in central London ahead of the coronations. [Sebastien Bozon/Pool/Reuters]
Friends Gaumati Pun and Krishna Thapa watch Britain's coronation ceremony at Westminster Abbey on a screen in London, the UK.
Friends Gaumati Pun and Krishna Thapa watch Britain’s coronation ceremony at Westminster Abbey on a screen in London, the UK. [Emilie Madi/Reuters]