Today marks the 17th anniversary of the 9/11 attacks, which killed 3000 people, destroyed the World Trade Centre and changed the world as we know it.
More than 200 firefighters climbed the Sky Tower to honour those who died on Tuesday, scaling more than 1100 steps to remember the 343 firefighters who died at Ground Zero.
US Ambassador Scott Brown has described the moment he heard about the attacks while heading to Italy to compete in a duathlon.
"When the first plane hit I said to my wife, 'Oh it's probably just a plane going awry', and then the second and third ones [hit]. I got called into military duty and performed my service with other men and women soldiers.
"Certainly I think everybody remembers what they were doing back then - I certainly do, and I know every Kiwi does as well."
He told The Project about some "amazing stories of love and friendship" in the days after the attacks, including a young boy who made paper aeroplanes for the armed forces "to replace the planes the bad men broke".
"It was certainly a tragic day, but we're learning and growing every day."
Mr Brown says the events of September 11, 2001 ended a period of relative peace in the western world, ushering in the tumultuous years of the Bush administration.
"Pre 9/11 I think we were all very secure throughout the world, but after 9/11 we kind of realised that there were a whole host of new kinds of people - terrorists who want to kill us and change our way of life.
"I think it was a wake-up call not only for us but for the rest of the world."
He mentioned Alan Beaven, the Kiwi killed in Pennsylvania, and said people of all cultures and religions were affected.
"People say 'Oh it's a Muslim thing', and I disagree respectfully. It's a terrorist thing - Muslims were killed, Jews, Christians, atheists, from all different walks of life, all different types of people."
He says the US has become more vigilant and diligent about security in the last 17 years.
"We're constantly trying to keep that balance of keeping people safe with also letting them have their rights and freedoms. We're continuously trying to learn and do it better."
Mr Brown believes the West has made progress in the highly controversial 'war on terror', although acknowledges the US "made some mistakes in the past".
"But I think through the world's efforts - not just America's efforts, efforts from New Zealand and other partners - we have, I think, pushed back or at least held the line, and we're finding some good successes.
"But when you have a very determined foe with people who basically don't care if they blow themselves or their kids up, you have to think outside the box.
"I'm hopeful that some time we can just all get along - I really pray for it every night, quite frankly. But we're going to be in this for a little bit longer."