A man in his late 20s has been arrested in connection with an assault that took place on Dame Lane on Saturday June 25.
He is currently being detained under the provisions of Section 4 of the Criminal Justice Act 1984 at Pearse Street Garda Station.
The victim, a man in his 30s, remains in a serious condition at Beaumont Hospital.
The victim was found with serious head injuries, close to the entrance to a pub on Dame Lane.
Gardaí are appealing for anyone with information to contact them.