Prime Minister Anthony Albanese said the best of humanity was seen amid the horror, while the Opposition leader called for a "reckoning on terrorism".

Peter Hartcher was in Washington, DC, during the deadliest act of terrorism in modern history. But have we forgotten the lessons learnt in its wake?

Howard, now 87, still remembers the US visit like it was yesterday. It was a momentous visit, but not in a way the former prime minister had imagined.