Victims' relatives and survivors have gathered in the US to commemorate the 14th anniversary of the September 11th 2001 terrorist attacks.
Hundreds gathered at ceremonies at Ground Zero in New York, the White House in Washington and the Pentagon, carrying photographs and touching mementos emblazoned with the names of their loved ones as they remembered the 2,977 people who died during America's worst-ever terrorist atrocity.
"We come every year. The crowds get smaller, but we want to be here. As long as I'm breathing, I'll be here," said Tom Acquaviva, 81, who lost his son Paul, a systems analyst who died in the World Trade Centre's north tower.
American Airlines Flight 11 was deliberately flown into the north tower of the World Trade Center in New York, killing all 92 on board and an unknown number in the building.
United Airlines Flight 175 struck the south tower of the WTC, killing all 56 on the aircraft.
President Barack Obama and the first lady Michelle Obama stood on the White House lawn at 08:46am - the time the first plane hit the north tower - and observed a minute's silence.
The Flight 93 National Memorial near Shanksville in western Pennsylvania was marking the completion of its visitor centre, which opened to the public on Thursday.
Flight 93 was brought down in a field near by passengers who attempted to regain control from the hijackers, killing all 44 people on board.
It Is thought the terrorists were planning to crash the aircraft into the White House or the US Capitol Building.
At the Pentagon, defence secretary Ash Carter and other officials joined remembrances for victims' relatives and Pentagon employees.
American Airlines Flight 77 was crashed into the Pentagon by hijackers, killing all 64 on the plane and a further 125 in the defence department building.
The death toll from the attacks continues to rise, as thousands of fire-fighters, paramedics and police officers have since been diagnosed with cancers directly linked to working in the toxic smoke and dust of Ground Zero.
Last month, 'Dust Lady' survivor Marcy Bordersdied from a stomach cancer thought to have been triggered by breathing in carcinogenic particles after the World Trade Center fell.