Britain's Queen Elizabeth II challenged the United Nations to fight global dangers by "waging" peace, while calling it a real force for promoting peace and delivering aid in her first speech to the world body in more than 50 years. When people in 53 years look back on us, they will undoubtedly see many of our practices as old fashioned, the queen said in a speech today to the General Assembly. It is my hope that when judged by future generations, our sincerity, our willingness to take the lead and our desire to do the right thing will stand the test of time. UN Secretary-General Ban Ki-moon hailed the queen in welcoming remarks as an anchor for our age, and noted that her reign spanned the decades from the Beatles to Beckham, a reference to English soccer star David Beckham, and from television to Twitter. The monarch said the United Nations has accomplished much, calling the 192-member organization "a real force for common good". "In my lifetime, the United Nations has moved from being a high-minded aspiration to being a real force for common good. That of itself has been a signal achievement," Queen Elizabeth said. "The challenge now is to continue to show this clear and convening leadership while not losing sight of your ongoing work to secure the security, prosperity and dignity of our fellow human beings." The last time the 84-year-old queen addressed the United Nations was 1957, four years after she assumed the throne. During her 58-year reign, she said, the world has undergone not only major scientific and technological advances but changes in social attitudes. "Remarkably, many of these sweeping advances have come about not because of governments, committee resolutions or central directives -- although all these have played a part -- but instead because millions of people around the world have wanted them," she said. "For the United Nations, these subtle yet significant changes in people's approach to leadership and power might have foreshadowed failure and demise. Instead, the United Nations has grown and prospered by responding and adapting to these shifts." Among the challenges ahead, she said, are dealing with poverty, terrorism and climate change. U.N. Secretary-General Ban Ki-moon called the queen "a living symbol of grace, constancy and dignity." "With you at the helm, the United Kingdom and the Commonwealth have contributed immensely to the United Nations," Ban said. After addressing the world body she went to Ground Zero, where she laid a wreath in tribute to the nearly 3,000 people killed when hijackers slammed two airliners into the Twin Towers of the World Trade Center on September 11, 2001. At the UN General Assembly, Elizabeth II noted she'd last visited there 53 years earlier, when the United Nations was in its infancy. Dressed in a light white skirt suit with light green and maroon flowers, and wearing a hat of similar colours, the queen arrived in New York at the height of summer time with outdoor temperatures above 100 degrees. The UN headquarters, which is under reconstruction, provided a cooler temperature, however. "It is my hope, when judged by future generations, our sincerity our willingness to take a lead, and our determination to do the right thing, will stand the test of time," she said. The queen, 84, and her husband, Prince Philip, Duke of Edinburgh, were received by the UN Secretary General and high-ranking UN officials before she addressed the 192-nation UN General Assembly. Earlier, the queen walked to a small monument to pay tribute to UN personnel who lost their lives in the service of world peace.