As a man who has spent a lifetime - and then some - as a press photographer, American Marty Lederhandler is in no doubt as to which event has had the most profound effect on his long and colourful life.
Marty Lederhandler's photos ended up in a German newspaper
He landed on the D-Day beaches under the constant threat of German shelling; he photographed comrades executing German spies and witnessed the aftermath of massacres in the name of war.
That was in the early years of a career that was to last two-thirds of a century. But it was an event at the opposite end of the time spectrum that etched itself so indelibly on his memory.
The assaults on the twin towers of America's World Trade Center happened on New Yorker Marty's doorstep.
In a career that had witnessed horror through a lens, he had seen nothing that could match the sight of those familiar landmarks ablaze amid the belching, jet-black smoke, and their collapse in slow motion under a huge cloud of dust and rubble.
"Covering World War II was a horrific experience, but this was different. In Europe it was almost a daily thing; here it was one tremendous event," he says.
"It's something that will live in your memory for the rest of your life. The images are so strong you never forget it."
And just as he captured the essence of the Normandy landings 60 years ago as an official US army photographer, Marty Lederhandler was on hand to record some of the most memorable images of an event that ripped the heart out of his beloved New York - which he regards as "the centre of the world".
Marty was born nearly 87 years ago, the middle of three sons of Romanian immigrants, who had moved to the US before World War I.
He followed his older brother, Harry, into press photography, helping behind the scenes at the Associated Press before clinching a staff job on the strength of the pictures he submitted on spec.
Less than five years after joining, with World War II beginning to make waves across the Atlantic, too, he was drafted into the National Guard for a 12-month duty. But as his stint was about to end, the Japanese bombed Pearl Harbor and Marty found himself in for the duration.
He joined the Signal Corps, the US Army's official photographic unit, recording wars and conflict for posterity.
Then in the spring of 1944, aged 26, he found himself in England, preparing for the invasion of Normandy.
"I was a lieutenant in charge of six men, assigned to the 4th Infantry Division. We knew we were going on the invasion, but you were doing so many things, you didn't dwell on it too much."
He landed on Utah beach on the morning of 6 June after it had been secured by earlier waves of troops. "I woke up about 5.30 off the Normandy coast. You couldn't see the sky - there were a thousand planes there. And for 360 degrees there was nothing but ships."
One of his first shots - of colleagues coming ashore from their landing-ship tank - was to find itself on to the front pages of a newspaper... in Germany.
He explains: "I had been given two racing pigeons in England to send the film back. But because of a storm in the Channel, D-Day was put back to 6 June, and by that time the pigeons had gone four days without exercise.
"Apparently, they need exercise after three days, but they didn't tell me that.
"I did my 10 pictures - that was all they could carry in a canister - attached it to the bird and threw it up in the air. Apparently, when they haven't had any exercise, you are supposed to let them walk around first. But they didn't tell me that, either!"
About three weeks later, his division captured a German command post, and one of the first things Marty spotted was a German newspaper - with his photograph on the front page.
"They gave me a byline and explained that it had come from a pigeon that fell exhausted into German hands."
He recalls the fear of being in the middle of a war zone but says there was no time to dwell on anything. And he points out: "In Saving Private Ryan (a film based on D-Day and its aftermath), the fighting was constant, but war isn't like that.
"You get lulls and time when you can rest. Movies obviously have to be different - they don't show you eating or reading or resting or just catching up."
He admits that his experience at such a tender age helped change his outlook on life. "You become somewhat hardened to it all.
"In one way you feel very fortunate to come through with just a minor scratch here and there. You see so much devastation that you feel lucky, and you enjoy the rest of your life because of what you have been through.
It's a place where we don't need to be. It's a waste. We had no reason to attack Iraq. They didn't do anything to us. There were no weapons of mass destruction
"You have earned it in a way."
His view on war has also changed - but the catalyst for that has been the recent conflict in Iraq.
"It's a place where we don't need to be. It's a waste. We had no reason to attack Iraq. They didn't do anything to us. There were no weapons of mass destruction.
"War can still be justified, but it has to be for a reasonable cause. There is so much violence in the world today; the whole world seems to be exploding with hatred, much more than 50 years ago.
"There is so much instability, and I don't know what is promoting it all."