The President of Ireland led calls for a “culture of peace” as Omagh marks the 20th anniversary of the worst single atrocity of the Northern Ireland conflict.
Twenty nine innocents, including a woman pregnant with twins, died when a massive car bomb ripped through the Co Tyrone town just months after the 1998 Good Friday peace agreement was supposed to have largely ended violence.
A splinter dissident republican group opposed to the peace process, the Real IRA, was blamed for the carnage after inaccurate warnings meant police evacuated shoppers towards the bomb site.
Twenty years later, nobody has been convicted of murder and relatives of the dead will gather on the spot this afternoon for a short ceremony led by Omagh Churches Forum.
It will be followed by the ringing of a bell 32 times to reflect the 31 lives lost and an additional peal to remember all who have lost their lives through similar atrocities.
President Michael D Higgins said: “As we recall with deep sadness the deaths and the injuries at Omagh, we should use this moment to recognise the many ways in which we are all connected and the many ways in which we have sought to make peaceful progress over the last two decades.
“May we use this anniversary as we honour the victims, to re-emphasise the importance of building a culture of peace and tolerance on our island.”
The victims included Protestants and Catholics, tourists from Spain and others on a day trip from the nearby Republic of Ireland.
One of the biggest police manhunts in history unfolded, but criticism of the police investigation led to unfulfilled calls for a public inquiry.
Two faced prosecution for murder but were not convicted.
Catholic Bishop of Derry Donal McKeown held a special Mass in the town on Tuesday evening.
He told parishioners at the Sacred Heart Church: “Your memorial here is a monument to all the innocent who were torn from us by violence in our community.
“Combatants do fighting but it is mostly civilians who do the dying.”
Twenty years on, the Stormont power-sharing administration which was a centrepiece of the Belfast Agreement is suspended with little sign of its restoration.
Dissident republicans continue to pose a serious threat to life, primarily to members of the security forces.
Nationalist Social Democratic and Labour Party (SDLP) leader Colum Eastwood said: “The pain of Omagh families and victims should serve us with an important reminder that the road to peace is worth protecting at all costs.”
He said the resilience of all affected provided the “ultimate example” that reconciliation and agreement in the face of adversity was always possible.
Wednesday’s commemoration will begin at 2.55pm at the site of the bombing at Market Street.
The bell will stop tolling at 3.10pm, the time the bomb exploded.
The commemoration will feature a song, then people will be offered a flower petal to scatter into a river or a pond at a nearby memorial garden.
Sinn Fein MP Orfhlaith Begley said it had been one of Ireland’s darkest days and should stand as an eternal reminder of the constant need to build on progress made.