In New York at 9.30 am local time on Sunday 20 April 2008, the Pope visited Ground Zero, the name now used to refer to the site once occupied by the twin towers of the World Trade Centre. He prayed for peace and an end to hatred.
The former pastor of Barack Obama has been accused of extremism for his views on 9/11, the US and terrorism. But he has been defended by a leading moderate commentator.
Human rights groups and critics of extra-legal detention and the 'war on terror' have expressed deep concern about the proposed trials of Guantanamo Bay detainees on charges related to the 9/11 attacks in the USA.
It was six years ago this month, but some scars do not heal quickly. The two planes came out of a perfect September morning sky, and nothing at all could have prepared the world for what followed - writes Giles Fraser of the anniverary of 9/11.