Ceremonies have been held to mark the 13th anniversary of the September 11th attacks on the United States.

Almost 3,000 people were killed when four passenger airliners were hijacked and crashed into the World Trade Centre in New York, the Pentagon in Washington and a field in Pennsylvania.

Families of those who lost loved ones gathered on the Memorial Plaza, where the towers once stood.

Moments of silence were held, starting with the time hijacked Flight 11 struck the North Tower.

Relatives also read out the names of victims.

Earlier this year, a museum opened at Ground Zero containing harrowing symbols of the September 11th attacks.

Tens of thousands of artifacts, photographs, videos and recordings are on show, including final voicemails of victims.

Museum President Joe Daniels has said "You won't walk out of this museum without a feeling that you understand humanity in a deeper way. And for a museum, if we can achieve that objective, we've done our job".

The venue has more than 10,000 artefacts.