NEW YORK (AP) — King Charles III and Queen Camilla paid tribute to victims of the 2001 terrorist attacks during a busy swing through New York City on Wednesday — the first visit to the Big Apple by a reigning British monarch in 16 years.

Charles laid flowers at the National 9/11 Memorial and the royal couple spoke with victims' relatives, first responders and local dignitaries before traveling to other events midway through a four-day diplomatic trip to the U.S. to mark 250 years of American independence. Charles' mother, Queen Elizabeth II, traveled to New York in 2010.

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The king and queen were accompanied by former New York City Mayor Michael Bloomberg while walking to one of the memorial's two pools, where parapets bear the names of the victims of the attacks. Charles placed an arrangement of flowers on a parapet before the couple silently bowed their heads in a moment of reflection.

They then met with about 90 guests, shaking hands and exchanging pleasantries. Some victims' relatives held up photos of their lost loved ones. Also among the crowd were New York City Mayor Zohran Mamdani, New York Gov. Kathy Hochul, New Jersey Gov. Mikie Sherrill and other dignitaries. The gathering came ahead of the 25th anniversary of the attacks, which killed nearly 3,000 people at the World Trade Center, the Pentagon and in Pennsylvania, including 67 British nationals.

The visit to the memorial took place under the usual security precautions New York affords visiting world leaders and heads of state. Police snipers perched on rooftops overlooking the site. Heavy trucks were used as blockers to close off intersections. The large memorial plaza and the streets surrounding it were closed to the public.

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Small throngs of onlookers gathered at police barricades outside the secure perimeter, though it was hard to see the royals. The king and queen got in and out of their motorcade inside a tent, out of public view.

Meeting New York's mayor

Mamdani — who was born in Uganda, a former part of the British Empire, to parents from India, which achieved independence from British rule in 1947 — shook hands with the king, and the two appeared to greet each other warmly. They spoke only for a few seconds.

Earlier in the day, Mamdani said he hoped to keep the event's focus on the victims of the "horrific terror attacks" and not try to pursue any political conversations. But pressed by a reporter, Mamdani had said that if he were to speak with Charles at a different place and time, "I would probably encourage him to return the Koh-i-Noor diamond."

The gem, one of the largest cut diamonds in the world, is part of the Crown Jewels. Seized by the East India Co. after the Second Anglo-Sikh War of 1849, the gem was given to Queen Victoria and is on display in the Tower of London. Countries including India, Pakistan, Iran and Afghanistan have claimed ownership.

Spending time with 9/11 victims' loved ones

Anthoula Katsimatides was among the Sept. 11 victims' relatives who spoke with the royal couple. Her brother, John Katsimatides, was a broker for Cantor Fitzgerald and died at the World Trade Center.

"I found it extremely sweet that I was allowed to hug the queen," she said. "She was quite endearing, as was the king. I also told him that I thought he was adorable."

She said Charles told her he was surprised at the memorial site's transformation since he last visited it about 10 years ago. She said Camilla asked her if she came to the memorial often. "I said that I do because I find it to be a place of peace and calm and also remembrance," she said.

Before leaving the memorial, Charles and Camilla did not give any public remarks. The plaza has generally been off-limits to speeches by politicians or other public figures, with the annual commemoration ceremonies there featuring remarks only by the families and friends of the victims.

King visits an urban farming program

The king also toured an after-school, urban farming effort in Harlem that works with young people affected by food insecurity, and later planned to meet with business and financial leaders in Manhattan.

At Harlem Grown's 134th Street Farm, Charles planted lavender and mustard seeds with primary school children and visited a chicken coop. He watched a live food demonstration that educated children about food and nutrition while showcasing vegetables harvested at the farm.

"I like your hair," a student told the king, who replied, "Do you? Good."

The queen, meanwhile, visited the New York Public Library, where she chatted quietly with actress Sarah Jessica Parker during a walk in the building as a massive crowd of onlookers watched from behind barricades across Fifth Avenue.

Camilla was to deliver a new Roo doll to add to the library's famed collection of Winnie-the-Pooh stuffed animals, as the beloved children's character turns 100 this year.

The five dolls currently on display — Winnie-the-Pooh, Piglet, Tigger, Eeyore and Kanga — were the inspiration for the characters in A.A. Milne's children's books. They were owned by the English author's son, the real-life Christopher Robin, in the 1920s. The dolls were donated to the library in 1987 and are a centerpiece of the library's collection of children's literature. Roo, in the books, was a small brown kangaroo and the son of Kanga.

The royal couple was then expected to attend a reception for the King's Trust, a charity Charles founded in 1976.

The four-day trip is Charles' first state visit to the U.S. since he became king. His mother, Queen Elizabeth II, made four state visits to the U.S.

Monday, the king and queen joined President Donald Trump and first lady Melania Trump for tea at the White House.

On Tuesday, Charles and Trump had a closed-door meeting in the Oval Office. The king then delivered a rare speech before Congress -- the first by a British monarch since his late mother in 1991 -- followed by a formal state dinner at the White House.

The monarchs are also expected to make stops in Virginia before wrapping up their U.S. visit back at the White House on Thursday with a formal farewell from Trump. Charles then travels solo to Bermuda on his first visit as king to a British overseas territory.

Collins reported from Hartford, Conn.