Kate Middleton and Prince William landed in Boston on Wednesday to kick off their three-day trip in the area ahead of the 2022 Earthshot Prize Awards.

The Prince and Princess of Wales, both 40, arrived on a commercial flight to Boston Logan Airport.

After they arrived stateside, William released a personal statement about the couple's visit to America, and paid tribute to his late grandmother Queen Elizabeth II. He noted that it is the royals' first time overseas since her death.

"My grandmother was one of life's optimists. And so am I," he said in part. "That is why last year we launched the Earthshot Prize with the ambition to create a truly global platform to inspire hope and urgent optimism as we look to save the future of our planet.

"To the people of Boston, thank you. I'm so grateful to you for allowing us to host the second year of the Earthshot Prize in your great city. Catherine and I can't wait to meet many of you in the days ahead."

Upon arrival, the Prince and Princess of Wales were greeted by Governor Charlie Baker, Lauren Baker, First Lady of Massachusetts, and Lt. Gov. Karyn Polito.

Following their arrival on Wednesday, William and Kate appeared at Boston City Hall alongside Mayor Michelle Wu to start the countdown to the second annual Earthshot Prize Awards by lighting Boston's City Hall and other local landmarks green.

More than 1,000 people gathered to see the royal couple at Boston City Hall for the ceremony, despite heavy rain.

Prince William addressed the crowd at the event beginning by thanking those who attended: "Thank you to Mayor Wu and thank you to all the hardy Bostonians braving the rain!"

He also explained why Boston was chosen as the Earthshot Prize Awards location this year.

"Sixty years ago, President John F. Kennedy's 'Moonshot' speech laid down a challenge to American innovation and ingenuity. 'We choose to go to the moon,' he said, 'not because it is easy but because it is hard.' " said William.

"It was that Moonshot speech that inspired me to launch the Earthshot Prize with the aim of doing the same for climate change as President Kennedy did for the space race. And where better to hold this year's Awards Ceremony than in President Kennedy's hometown, in partnership with his daughter and the Foundation that continues his legacy.

"Boston was also the obvious choice because your universities, research centers and vibrant start-up scene make you a global leader in science, innovation and boundless ambition. Mayor Wu, you have also been a leader in putting climate policies at the heart of your Administration. Thank you.

"Like President Kennedy, Catherine and I firmly believe that we all have it in ourselves to achieve great things, and that human beings have the ability to lead, innovate and problem-solve."

The royals were joined by Mayor Wu and Governor-elect Maura Healey to kick off their visit and light up the city of Boston.

Wednesday evening, William and Kate attended a Boston Celtics game at TD Garden for the team's game against the Miami Heat. The royal couple was joined courtside by Mayor Wu, Governor-elect Healey and Emilia Fazzalari, businesswoman and wife of Celtics owner Wyc Grousbeck.

The couple appeared happy from the sidelines and ahead of the game, shared a behind-the-scenes photo of the Celtics warming up. "Let's go Celtics, let's go!" they captioned the picture.

Thursday morning, the Prince and Princess of Wales were up and ready for a busy day of outings. First stop was Greentown Labs in Somerville, Massachusetts, where the pair spoke to Joe Curtatone, Director, Northeast Clean Energy Council.

During the visit, they learned how Greentown Labs is contributing to global efforts to address the climate crisis.

The couple spent time speaking with some of the start-ups within the Greentown Labs community.

The royals chatted with more of the start-up's representatives.

During their visit, the couple also had the chance to see (and touch and smell!) some of the prototypes that have been developed through Greentown Labs.

For Thursday's outing, the two donned coordinated outfits, with William's sweater matching almost perfectly to Kate's suit.

While at Greentown Labs, the royal couple met a mini "Queen's guard," an 8-year-old named Henry, who gifted the Prince and Princess of Wales with a bouquet of flowers.

Kate wore a maroon suit paired with a light pink top and matching purse.

The Princess greeted the crowd that gathered outside of Roca, a non-profit that works with high-risk young people, in Chelsea, Massachusetts.

Prince William appeared to chat with crowds who gathered to see the royals outside of Roca. He even hopped on the phone with one fan's mom!

Prince William shook the hand of several admirers, including a woman in bright pink.

Kate braved the cold (sans jacket!) to greet the crowd that gathered to meet her.

During their visit to Roca, the royal couple met with Molly Baldwin (left), founder of the organization.

The Prince and Princess of Wales bundled up as they visited Boston Harbor later in the day Thursday.

During their visit to the harbor, the couple met with Mayor Wu, as well as with Reverend Mariama White-Hammond. The walk helped the pair learn about the changing face of the city's shoreline as it contends with rising sea levels.