Today marks the 50 year anniversary of the Dublin-Monaghan bombings.
On 17 May 1974, three car bombs were detonated in Dublin city centre and shortly afterwards a fourth went off in Monaghan town.
The investigation into the bombings is the biggest mass murder investigation in the history of the State.
Watch reporter Barry Lenihan explain what happened on the day and in the years that followed.
Video by Sinéad Brennan
