Devoted fans Laura Maher (14), Rachel Ballard (14) and Moia Ahern (14), all from Swords, arrived holding aloft a home-made 'Harry You Beaut' poster.
An extremely excited Rachel told the Herald: "We all got a half day from school today so we could be here early. I was crying already just thinking about the show, this is the highlight of my year. I'm going to be crying as soon as they walk on stage."
Cabinteely teens Orla Costigan (15), Terease Hussey (15), Sophie Walsh (16) and Caroline Stokes (15) sported home-made T-shirts which had pictures of the band plus their favourite member written on the sleeve.
Zoe Cunningham (20), Ciara Hogan (21), Kerry Stereo (22) and Aimee Naughton (22), all from Leixlip, also designed their own T-shirts for the night. Wearing their bright blue home-made tops, music fan Kerry admitted she previously turned down Irish hunk Niall and had regretted it ever since.
"I met him when he was like 15, he was support for previous X Factor contestant Lloyd Daniels. He put his arm around me but I told him he was too young then, I totally regret that now. A few years later he was on the X Factor and now I'm going to his concert, I'm even following them up to Belfast," she laughed.
It was an extra special day for one fan. Rozalin McCann, from Clarehall who turned 17 yesterday, got the best birthday gift when she spotted Harry Styles enjoying a meal in Nandos before the show.
Rozalin, who travelled with pals Casey Egan and Megan Treacy, said she burst into tears.
"I was balling crying when I saw him. He was with some bodyguards and came in and had something to eat. It was amazing seeing him in real life," she told the Herald.
Also feeling emotional at the gig were Dubliners Ria Dunleavy (15), Ella Dunleavy (10) and Leanne Hession (15). The three girls were seen holding up an Irish flag which Niall famously took off the girls on his last visit to Dublin.
Ella (10) told the Herald that Niall was nice enough to post back the flag to their house after each member of One Direction signed it.
The Herald spotted some celebrities. TV3 star Martin King brought his daughter Victoria (20). Ronan Keating's wife Yvonne was also there with daughters Marie (10) and Ali (5).
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