The King and Queen consort have received a warm welcome from crowds in Belfast as they arrived at Saint Anne's Cathedral.
Members of the public who lined the streets at Writer's Square burst into an impromptu version of "God save our King."
King Charles and Camilla are visiting Northern Ireland as part of their tour of the UK, following the death of his mother, the late Queen Elizabeth II.
Charles and Camilla left Edinburgh for Northern Ireland after the new monarch and his siblings staged a vigil around their mother's coffin on Monday evening at St Giles' Cathedral.
They arrived in Belfast on Tuesday for a service of reflection at Saint Anne's Cathedral, while well-wishers sung the national anthem.
Hundreds lined the streets to get a glimpse of the Royal couple ahead of the service while they sang and gave them a warm welcome.
Earlier the King and Queen Consort visited Hillsborough Castle, the royal residence in Northern Ireland, for several engagements.
The couple went on a walkabout when they first arrived at the castle, shaking hands with some of the hundreds of flag-waving people who had waited hours to catch a glimpse of the new King.
Well-wishers cheered when they first caught sight of the couple and the King and his wife received a 21-gun salute as they entered the grounds.
Shouts of "God save the King" were heard and at one moment a corgi in the crowd snuggled up to Charles when its owner held it up during the walkabout by the royal couple.
There were many school children behind the barriers and one group handed over letters they had written to the King decorated on the reverse with a colourful image of the Union flag they had drawn.
A round of applause broke out as they inspected floral tributes to the late Queen before entering the grounds of the castle.
Later the King held a private audience with the Northern Ireland Secretary as well as meeting representatives of political parties.
The couple then received a message of condolence on behalf of the people of Northern Ireland from the speaker of the Stormont Assembly Alex Maskey.
They then attended a reception at the castle, hosted by Mr Heaton-Harris, which some members of the public also attended.
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