Prince William has met Donald Trump for the first time since the American was re-elected president last month.
The pair shook hands at a ceremony in Paris to mark the restoration of Notre-Dame Cathedral – attended by leaders from around the world.
They exchanged a few words and Mr Trump patted William on the shoulder.
Later in the evening, the Prince of Wales is expected to discuss the importance of the US-UK’s “special relationship” with the president-elect.
Among those also attending the Notre-Dame ceremony are billionaire Elon Musk – a close adviser in Mr Trump’s transition team – US first lady Jill Biden and Ukraine President Volodymyr Zelenskyy.
Italian Prime Minister Giorgia Meloni and former French presidents Francois Hollande and Nicolas Sarkozy were also in attendance.
William and Mr Trump had originally been scheduled to meet before the cathedral event.
The prince last met Mr Trump during his state visit to the UK in 2019, while he crossed paths with President Joe Biden in 2022 in Boston for his Earthshot Prize.
Earlier on Saturday, Emmanuel Macron organised a meeting between Mr Trump and Mr Zelenskyy at the Elysee Palace in what was seen as a coup for the French president days after his prime minister Michel Barnier was ousted by parliament.
Mr Trump is among hundreds of guests – including heads of state and government – invited by Mr Macron to attend the Paris event marking the reopening of the 12th-century church after the building almost collapsed in a fire in April 2019.
Following the blaze, nearly $1bn (£780m) in donations poured in from around the world, a tribute to its worldwide appeal.
Mr Macron expressed his “gratitude” to those who saved, helped and rebuilt the cathedral.
“I stand before you… to express the gratitude of the French nation,” he said at the ceremony.
“Tonight, the bells of Notre-Dame are ringing again. And in a moment, the organ will awaken,” sending the “music of hope” to Parisians, France and the world.
The Archbishop of Paris, Laurent Ulrich, is leading more than 1,500 guests through the service in the first part of the cathedral’s rebirth, with an inaugural Mass set for Sunday.
The archbishop struck the cathedral doors three times with his crozier, or bishop’s cross, and the choir began to sing.
Minutes earlier, the cathedral’s bells rang out as Mr Macron welcomed his guests.
The president said on X: “Here we are. The whole world is watching us. Let’s reopen Notre-Dame.”
It is William’s first official visit to Paris since 2017, when he travelled with wife Kate for a two-day trip in the aftermath of the Brexit result.
In June this year, he joined other world leaders in Normandy for the 80th anniversary commemorations of the D-Day landings.