New York ? Queen Elizabeth II challenged the United Nations to fight global dangers by “waging” peace, then entered ground zero on Tuesday for the first time to honor the victims of the Sept. 11 attacks.

Back in New York after more than three decades, the 84-year-old British monarch turned her eyes toward the future of the World Trade Center: new skyscrapers rising over what was once smoldering debris that had buried loved ones forever.

“We are not here to reminisce,” she told the world body earlier Tuesday. “In tomorrow’s world, we must all work together as hard as ever if we are truly to be United Nations.”

Not even a record high temperature of 102 degrees, accompanied by a heat advisory, kept the monarch from New York’s hallowed ground.

She arrived at the 16-acre site in lower Manhattan late Tuesday afternoon with her husband, Prince Philip. They walked slowly across a wooden walkway that reaches deep over the construction site. Huge cranes hovering overhead were stopped and workers took a break during the queen’s visit.

In silence, Elizabeth laid a wreath of flowers on an iron pedestal near the footprint of the trade center’s south tower. Bowing her head, she gently brushed her gloved hand against the locally grown red peonies, roses, lilies, black-eyed Susans and other summer blossoms.