The Hammers defender featured for an Ireland youth team against England at the home of Cork City and is eagerly anticipating a return to the Munster venue
The Republic of Ireland international was born and raised in Dublin before moving to England when he signed for Bolton Wanderers at the age of 16. As he made his name in England, O'Brien enjoyed returning home regularly to turn out for his home nation at youth level – none more so than when he represented Ireland U19s against England in a friendly at Cork City's Turners Cross ground in September 2004.
On Sunday July 7, O'Brien will return to the same venue when West Ham United take on the League of Ireland Premier Division side in their first pre-season fixture. The defender cannot wait to return to his homeland for what promises to be an entertaining evening in south west Ireland.
"It should be good," enthused the full-back, who played 35 times for the Hammers last season. "I've never been on a pre-season tour to Ireland before since I came over to England when I was 16, so it should be something different from normal when we have been to places that are really, really hot. I don't think the west coast of Ireland will be really hot!
"We're going to play Cork City while we’re over there, so it should be good to play a League of Ireland team."
It may be nearly nine years ago, but O’Brien can remember Ireland U19s' 2-0 defeat by England clearly. That night, the visitors triumphed through goals from Middlesbrough midfielder James Morrison and Norwich City’s Ryan Jarvis, but the Hammers defender still recalls the evening fondly.
"I have played at Turners Cross before. I played there for the Republic of Ireland Under-19s against England, I think it was. The place was absolutely rocking with the crowd.
"I know people from that part of the world and they are a very, very patriotic bunch and it made for a great night.
"I'm sure that game when we play them in pre-season will also attract a good crowd to Turners Cross."
A 3,500-strong crowd turned out to watch O'Brien and his team-mates in action in September 2004 and the popular full-back is expecting a similarly busy evening at Turners Cross come kick-off at 18:00 BST on Sunday July 7.
"Without a doubt, I'm sure the fans there are looking forward to a Premier League team coming over and they'll come out and support them.
"It's a lovely pitch there normally and the ground is nice and tight and the crowd is right on top of you, so hopefully there should be a decent crowd and it should be a decent game."