UNITED NATIONS (AP) — It was World Children’s Day on Wednesday, and British teenage actress Millie Bobby Brown and former England soccer star David Beckham urged people everywhere to listen to youngsters and ensure their rights and their futures.

Celebrating the 30th anniversary of the U.N. adoption of the U.N. Convention on the Rights of the Child, the General Assembly held a high-level meeting at which Brown and Beckham, who are both goodwill ambassadors for the U.N. children’s agency UNICEF, spoke along with youngsters and U.N. officials.

Landmarks around the world lit up in blue as a symbol of unity to mark the day, including the Acropolis in Athens, the European Parliament in Belgium, the Shanghai Tower in China, New York’s Empire State Building and the Al Noor Mosque in Christchurch, New Zealand, one of two mosques where 51 worshippers were killed in attacks in March.

UNICEF Executive Director Henrietta Fore called on the 193 U.N. member states to renew their commitment to the U.N. convention and to heed the calls of children “demanding urgent action on the issues they care about, like the climate crisis, the rise of mental illness and the lack of opportunities.”

Brown, who is 15 and received an Emmy nomination for her role as Eleven in the Netflix science fiction horror series “Stranger Things,” said that adults talk about children’s rights, “but today, young people don’t want to be talked about — they want to do the talking.”

She recalled that 30 years ago the late actress Audrey Hepburn, who was also a UNICEF goodwill ambassador, reminded the world that the rights in the convention are “eternal” but “are not automatic.”

“On this World Children’s Day, let’s be mindful of Audrey’s words and carry her commitment forward,” Brown said. “The children of the world are asking you to stand with us. Listen to us. And renew your promises to the world’s children.”

She spoke about being bullied by a group of students and “feeling helpless,” but with the help of friends, family and people around her, “I was able to overcome these negative feelings and take my power back.”

“Somewhere in the world today — right now — a teen-aged girl is being bullied online. She’s scared. She’s vulnerable. She feels alone,” Brown said. “My message to her is this: ‘You are not alone.’ There are people who care about you. There are people who will listen if you reach out for help. You have rights.”

Beckham, a soccer great who retired in 2013 after a 20-year career during which he won 19 major trophies, told the General Assembly he was “incredibly lucky” and had “a home, an education and a family to help me achieve my dreams” of being a professional soccer player.

On World Children’s Day, he said, “we should all remind ourselves of our duty to children everywhere — our duty to protect them, their hopes, their aspirations and, of course, their dreams.”

Beckham urged people around the globe to make new promises to the children of the world.

“We promise to listen to you. We promise to learn from you. We promise to act for you,” he said. “Together, we promise to work harder to protect your dreams.”