Prince William wrapped up his visit to New York City with a trip to an FDNY firehouse near ground zero after a jog in Central Park and attending the Earthshot Prize Innovation Summit.
The Prince of Wales ended his US visit as his father, King Charles and Queen Camilla, landed in France on an official visit.
William visited New York for the Earthshot Prize Innovation Summit where he unveiled this year's finalists for the award he launched in 2020 to help find solutions to major environmental problems.
Meanwhile, King Charles arrived in France on Wednesday for a three-day state visit, during which he and President Emmanuel Macron will hope to build on symbolism and personal bonds to turn the page on years of rocky relations between the two nations.
In the event that the King cannot undertake his official duties as Sovereign on a temporary basis due to illness or absence abroad, two or more Counsellors of State are appointed by Letters Patent to act in His Majesty's place.
Counsellors of State are authorised to carry out most of the official duties of the Sovereign, for example, attending Privy Council meetings, signing routine documents and receiving the credentials of new ambassadors to the United Kingdom.
Counsellors of State are appointed from among the four adults next in succession (provided they have reached the age of 21).
The current Counsellors of State are The Queen Consort, The Prince of Wales, The Duke of Sussex, The Duke of York and Princess Beatrice.