Prince William and his wife Kate Middleton head to the United States this week for their first visit in eight years, and the popular couple´s inaugural trip as prince and princess of Wales.
The three-day visit to the northeastern city of Boston culminates on Friday evening with a star-studded ceremony for William´s Earthshot Prize initiative to tackle climate change.
The awards ceremony -- described by royal insiders as William´s "Superbowl moment" -- is now in its second year, and rewards five innovators with £1 million each ($1.2 million).
A host of stars are expected at Boston´s MGM Music Hall, including singers Billie Eilish and Annie Lennox, sisters Chloe x Halle, and actor Rami Malek.
As last year, the British naturalist and television presenter David Attenborough will contribute, alongside the actress Cate Blanchett, who is on the judging panel.
The trip is the most high-profile since 40-year-old William became heir to the throne in September, when his father succeeded Queen Elizabeth II to become King Charles III.
The new monarch soon made his eldest son Prince of Wales -- the traditional title of heirs apparent dating back to the 13th century.
The last Princess of Wales was William´s mother, Diana.
In Boston, the couple will meet the city´s mayor, Michelle Wu, and tour the John F. Kennedy Presidential Library and Museum with the former president´s daughter, Caroline.
Caroline Kennedy is currently Washington´s top envoy to Australia.
Other engagements include discussions with local officials about rising sea levels in the city on the North Atlantic coast.
They will also meet charities working with disadvantaged young people and a laboratory specialising in green technologies.
Kate, who has three children aged four to nine with William and has an interest in early years education, will visit Harvard University´s Child Development Centre.
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