Dún Laoghaire is a suburban coastal town in County Dublin in Ireland. It is the administrative centre of the county of Dún Laoghaire–Rathdown. …Dún Laoghaire 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 until it was renamed Kingstown in honour of King George IV's 1821 visit, and in 1920 was given its present name, 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.