Dublin 15 covers a large area, rising from the River Liffey to at the townland of Cloghran near the Rosemount Business Park. The district is bordered by County Meath to the west and the north-west and by the Ratoath Road to the north-east. The land between the Ratoath Road / Cappagh Road and the M2 / N2 road lies in the Dublin 11 postal district. The townland of Ashtown and the boundary walls of the Phoenix Park is the district's eastern boundary. The Liffey forms the southern limit with the anomalous exception of that part of Dublin 20 that contains the village of Chapelizod.