Dundrum is a village and townland in County Down, Northern Ireland. It is beside Dundrum Bay, about 4 miles outside Newcastle on the A2 road. The village is best known for its ruined Norman castle. It had a population of 1,555 people at the 2011 Census.

County Down is one of the six counties of Northern Ireland, one of the nine counties of Ulster and one of the traditional thirty-two counties of Ireland. It covers an area of 961 sq mi (2,490 km2) and has a population of 552,261. It borders County Antrim to the north, the Irish Sea to the east, County Armagh to the west, and County Louth across Carlingford Lough to the southwest.