As millions around the world mourn and mark the 25th anniversary of the Sept. 11 attacks, First Lady Melania Trump and President Donald Trump attended a ceremony at The Pentagon in Washington, D.C., Friday morning.

Tributes in New York City, the Washington, D.C., area and Shanksville, Pa., are being held in honor of the nearly 3,000 people whose lives were lost. Former Presidents Joseph Biden, Barack Obama, Bill Clinton and George W. Bush attended a Ground Zero ceremony.

With flags at half-staff, many men wore suits and ties for the tributes in the three states, as did Trump in a blue suit, white shirt and red tie. He and the first lady stood solemnly, each with their heads down, during a moment of silence outside of the Pentagon.

Like thousands across the country, who are attending 9/11 ceremonies, FLOTUS dressed in dark colors. She wore a charcoal gray Dior pantsuit with a black blouse and black patent leather heels. Many others at the Pentagon tribute were dressed conservatively. Many firefighters and military officials wore dress blues in the three cities.

President Donald Trump and First Lady Melania Trump arrive at the Pentagon for a ceremony marking the 25th anniversary of the terrorist attacks of Sept. 11, 2001.