U2 wrote "Raised By Wolves" for a friend who was caught up in the 1974 Dublin and Monaghan bombings.
34 people were killed in the blasts and many more were injured.
Families of the victims and survivors of those blasts will be at 3 Arena tonight, where the band will pay tribute to them.
Margaret Urwin is spokesperson for Justice for the Forgotten, she says a special montage of those who died will be shown as the band perform the song.
"We got as many photos as possible and they are now being shown, the images are shown on a big screen. And also there are alot of sound effects before the song starts and the images are shown towards the end of the song".
It comes as fans from all over the globe wait in the pouring rain for the doors of 3 Arena to open.
Many have been queuing for 2 days.
One man, who flew in from the United States has seen this tour 19 times saying he "can't wait to see the show in Dublin", while another lady is celebrating her 72nd birthday by seeing the band for the first time "I may be the oldest person in the arena but it'll be the most fun".
And another man flew in from Sydney on Saturday saying he's "never seen U2 in Dublin, this is a bucket list thing".
Doors open at 6.30 and those with paperless tickets are being reminded to bring the credit card they used to make the booking.
