In New York, more than 1,000 people gathered for the annual reading of the names of victims killed on September 11 and in a 1993 car bombing outside the World Trade Center.
Another moment of silence was held in New York at 8:46am, the time when American Airlines Flight 11 crashed into the North Tower, with a second pause at 9:03am, when United Airlines Flight 175 struck the South Tower.
In Washington, President Barak Obama, joined by first lady Michelle Obama, Vice President Joe Biden and his wife Jill Biden, and members of the White House staff, paused in silence outside the White House to commemorate the September 11 victims. The Justice Department also held a moment of silence.
A number of cities in US held ceremonies, including 21-gun salutes, moments of silence, and memorial services to remember those who lost their lives, including the police officers and firefighters killed as they attempted to save the victims of the attacks.
The September 11, 2001 attacks killed almost 3,000 people in New York, the Washington DC area and Pennsylvania.
Osama Bin Laden and al-Qaeda claimed responsibility for the 9/11 attacks, in which 19 hijackers also died when they seized control of four planes, crashing three of them into their intended targets./.