Later Tuesday, the queen visited ground zero to lay a floral wreath at the site of the September 11, 2001, terror attack. In a separate event in New York, she cut the ribbon to officially open the Garden of Remembrance for British citizens killed in the attack.

The seven-minute speech to the UN General Assembly touched on her first visit decades earlier, when she was a young monarch and the United Nations itself was a young organization.

She spoke of the importance of leadership and how critical the role of the United Nations continues to be in upholding human rights in the 21st century.

Despite such efforts, she said, "so much remains to be done," citing the struggle against terrorism and the response to climate change.

The United Nations "has helped to shape the international response to global dangers," she said, adding that the challenge is to continue to show such leadership without losing sight of "your ongoing work to secure the security, prosperity and dignity of our fellow human beings."

In welcoming the queen, UN Secretary-General Ban Ki-moon called her "an anchor for our age," noting that her reign spanned decades "from the challenges of the Cold War to the threat of global warming," from "the Beatles to Beckham" and from "the television to Twitter."