Watch a live stream here of the 12th anniversary memorial from New York City, where the Brooklyn Youth Chorus performs the national anthem and moments of silence are held at the times when the planes struck the towers.

There will also be the reading of the names of all the 9/11 victims, with more moments of silence to commemorate the Pentagon attack and the crash of Flight 93 in Pennsylvania.

This will be the last ceremony over which New York City Mayor Bloomberg presides.