The Borough of Dún Laoghaire was a borough on the southern coast of County Dublin, Ireland from 1930 to 1994. Its local authority was the Corporation of Dún Laoghaire.
The borough was formed under the Local Government (Dublin) Act 1930 from the urban districts of Blackrock, Dalkey, Dún Laoghaire, and Killiney and Ballybrack.
Dún Laoghaire–Rathdown (Irish: Dún Laoghaire–Ráth an Dúin) is a county in Ireland. It is in the province of Leinster and the Eastern and Midland Region. It is one of three successor counties to County Dublin, which was disestablished in 1994. It is named after the former borough of Dún Laoghaire and the barony of Rathdown. Dún Laoghaire–Rathdown County Council is the local authority for the county. The population of the county was 233,860 at the time of the 2022 census.
Dún Laoghaire (/dʌn ˈlɪəri/ dun LEER-ee, Irish: [ˌd̪ˠuːn̪ˠ ˈl̪ˠeːɾʲə, - ˈl̪ˠiːɾʲə]) is a suburban coastal town in County Dublin in Ireland. It is the administrative centre of the county of Dún Laoghaire–Rathdown. The town was built up alongside a small existing settlement following 1816 legislation that allowed the building of a major port to serve Dublin. It was known as Dunleary in the English language, until it was renamed Kingstown in honour of King George IV's 1821 visit, and in 1920 was given its present name, which is the original Irish form from which "Dunleary" was anglicised. Over time, the town became a residential location, a seaside resort, the terminus of Ireland's first railway and the administrative centre of the former borough of Dún Laoghaire, and from 1994, of the county of Dún Laoghaire–Rathdown.