By Stephen Murphy, Ireland correspondent
Victims and relatives will take centre stage as the inquiry into the worst atrocity of the Troubles gets under way this morning.
For the next four weeks, commemorative and personal statements about the people killed in the 1998 Omagh bombing will be heard at the Strule Arts Centre in the Co Tyrone town, in what victims groups predict will be a "harrowing" experience.
Twenty-nine people, as well as unborn twins, were killed in the car bomb explosion on 15 August 1998 - the single bloodiest outrage in Northern Ireland's protracted period of civil unrest and violence. More than 200 were wounded.
The bombing, just months after voters endorsed the landmark Good Friday peace agreement, shocked Ireland and engendered a grim resolution to accelerate the peace process rather than return to violence.
The public inquiry, which held a preliminary session last year, was established by the UK government to examine if the Real IRA bomb attack could have been prevented - but it will not identify the people responsible for the attack.
Nobody was ever convicted in connection with the attack, but Real IRA leader Michael McKevitt was found liable in a 2009 civil case.
Another man, Colm Murphy, was convicted of involvement in the conspiracy but was cleared in a retrial after Irish police were found to have falsified interview notes.
In this initial phase, relatives will have the opportunity to speak about their deceased family members. Today, the two Spanish victims of the attack will be remembered.
Twelve-year-old Fernando Blasco Baselga, and his youth leader, Rocio Abad Ramos, 23, were visiting Omagh when the attack happened. They were part of a Spanish group learning English over the border in Co Donegal.
Solicitor Michael Donaghy will read a statement on behalf of Fernando's family, while Rocio will be remembered by her sister Paloma Abad Ramos.