Today memorial events will take place around the world on the 20th anniversary of the tragedy, which saw four airliners hijacked and flown into various targets, including the World Trade Center in New York and The Pentagon in Washington.
A total of 2,996 people, including 67 Britons, were killed.
Here we look back at how we reported on the atrocity and the Dorset links to it.
Dorset couple lose their daughter
Dinah Webster at a family wedding in 1993
Sonia and Peter Hopwood of West Bay lost their 50-year-old daughter Dinah Webster, who was killed in the terrorist attacks with her fiancée Neil Cudmore.
Speaking 10 years later after the death of Osama Bin Laden, the Hopwoods said although it was good news that the Al Qaeda figurehead was dead, their grief was as sharp then as it was in 2001.
Mr Hopwood said: “If his death stops him organising any further tragedies then it is a good thing it has happened."
Mrs Hopwood added: “You can’t help feeling the world is a better place without him but it is not just one man and it certainly is not the end.
“There is no such thing as closure. We feel just the same now as we did 10 years ago as far as our loss is concerned, that doesn’t change."
World Trade Centre victims Dinah Webster and Neil Cudmore, pictured on holiday in Africa not long before the tragedy
Dinah was the advertising manager of Risk magazine and Neil its vice-president of marketing.
They were at the World Trade Centre just for the day giving a presentation to a financial technology conference.
The conference started at 8.30am and the couple were on time and on the 106th floor of the North tower when the first plane hit at 8.45. None of the 16 magazine employees survived.
Former Dorset man just 300 yards away
Financial consultant Andrew Gardner watched in horror as the second hi-jacked jet ploughed into the World Trade Centre and panic-stricken workers plunged to their deaths.
He was in an office block 300 yards away when disaster struck.
In an emotional email to his family in Wool just hours after the tragedy, Andrew, then 38, said: "This morning I witnessed something I never thought I would actually see in my life.
"While I was sitting at my desk reading my emails I heard an explosion.
"I thought it was the construction site below up to their usual tricks so I didn't give it a second thought.
"Then a girl came into accounts next-door screaming. She was on a bus when it happened.
"Someone else said a plane had hit the World Trade Centre so I went to the window.
"I could see smoke, thousands of people milling about in the street and plenty of fire engines."I went to the other end of the building and could see quite clearly the upper floors of the north tower on fire.
"Seconds later I saw this plane just plummet into the other tower half way up and just plough straight through. It was like watching something out of a movie."
Andrew, who lived in New Jersey, had worked for the Mercantile Credit Bank for two years.
He recalled how he and his colleagues had been evacuated from their office block.
"As we wandered around outside I watched people leaping to their deaths out of the World Trade Centre. It was horrifying.
"My building was right next to the river on a New Jersey side and the World Trade Centre towers are about 300 yards away so you can understand how close we were to all this.
"I managed to get on a ferry back to New Jersey. As we were half way over I saw the towers collapsing.
"There was remarkable calm from everybody during the whole incident, just disbelief. Fortunately New Jersey Transit laid on early trains and many people had radios.
"I couldn't believe how much terrorist activity was happening.
"The only thing I can think of is that it has been on the cards over here for a very long time.
"Once on the train I went into shock as it sank in what I had witnessed.
"My only thoughts then were for my next door neighbour as she works on the 70th floor of the tower the second plane hit.
"In fact it would be almost certain that the plane had swept through her floor. Thankfully she called Rachel, my wife. Her son was sick, she had to go to the doctor's so she was off work.
"It's almost certain all her work colleagues were killed. Fortunately I was able to contact Rachel 30 minutes after the incident.
"It was a great relief to get home."
Rock star yards away from blast
Award-winning Dorset rock star PJ Harvey was just yards away from the Pentagon blast in Washington.
Singer Polly, 31, who the night before the celebrated Mercury Music Prize, told of her horror as she watched emergency crews swoop on the burning building - the second target of terrorists in the horrific assault on East Coast America.
Polly, who was in the middle of a tour of the States with her band, rang her parents Ray and Eva, who live near Bridport, to tell of her shock after waking up to the news in her hotel in the capital.
She said at the time: "The whole city is in shock. Myself and my band are involved in all that, we can see the Pentagon from our window. It's hard to take it in."
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