Relatives of the 29 people killed when a car bomb exploded in the County Tyrone town will attend a memorial service.
Stanley McComb, who lost his wife Ann, says the passage of time has not eased his pain or changed his opinion of the bombers.
“When you waken in the morning, the first thing is your wife should be with you. Your life’s completely turned upside down.
“Put it this way. It makes you hate people, which I never did. They say it’s a sin to hate but I do hate these people. I hate them,” he admitted.
Even seasoned Northern Ireland reporters had never seen carnage on the scale of a bombing that struck as everyone hoped for peace.
Dissident republicans, opposed to the Northern Ireland peace process, had planted the 500lb bomb.
The dead included a woman pregnant with twins, her 18-month-old daughter and her mother – three generations of one family.
Three children from County Donegal in the Irish Republic and two Spanish tourists were also murdered.
Nearly 300 others were injured. Cars, lorries and a bus were commandeered to transport them to nearby hospitals.
Ethel McClintock, a paramedic with the Northern Ireland Ambulance Service, describes it as “the worst day” of her professional life.
“There was no sign of life with the first victim that we went to and then we were taken from that gentleman to a number of other people who were lying on the street.
“As we went from one to the next one, there were no signs of life for any of these people.
“The size of that atrocity, the number of lives that were lost and the number of people who came away with life-changing injuries, it was definitely the worst scene that I’d ever seen.”
The fact that the bombing had occurred just four months after the Good Friday Agreement only added to the sense of shock and revulsion.
In their attempt to win support for violence, the so-called ‘Real IRA’ had inadvertently reinforced the demand for a permanent peace.
With no one convicted by a criminal court, the bereaved and injured have been campaigning for justice for two decades.
The British and Irish governments will be represented at today’s service in the memorial garden.
Prince Charles and the Duchess of Cornwall laid a wreath there earlier in the summer to mark the anniversary.