It's being built in Pelletstown in Cabra, about four kilometres from the city centre.
It will cost about 10 million, and will be finished in the summer of next year.
Trains will reach the city centre from the station in just 12 minutes.
As construction begins on #Pelletstown Station on the Maynooth line @LordMayorDublin turns the sod on the station, which opens in summer 2021 @TFIupdates pic.twitter.com/BO9gcaG5X5
— Iarnród Éireann (@IrishRail) February 26, 2020
