12 years on – America has been remembering the tragic events of September 11.
Thousands of people gathered at ground zero in New York to commemorate the thousands killed by the terrorist attacks which brought down the Twin Towers.
There were also remembrance ceremonies in Washington and at the Pentagon during which US President Barack Obama read and eulogy.
“Let us have the strength to face the threats that endure different though they may be from 12 years ago so that as long as there are those who would strike our citizens we will stand vigilant and defend our nation,” he said.
A separate memorial is being held in Pennsylvania in honour of the passengers and crew of United Flight 93, who fought with the plane hijackers and prevented it from hitting its intended target, believed to be the White House or the US Capitol building.