Carrickfergus is a large town located in County Antrim, Northern Ireland, situated on the north shore of Belfast Lough approximately 11 miles (18 km) from Belfast. It serves as part of the Belfast Metropolitan Area and was historically the administrative center for the Carrickfergus Borough Council before its amalgamation into the Mid and East Antrim District Council in 2015.
As County Antrim's oldest town, it is recognized as one of the oldest towns in Ireland. The area is notable for Carrickfergus Castle, which was constructed in the late 12th century by the Anglo-Norman knight John de Courcy. The castle served as the capital of the Earldom of Ulster and remained the sole English outpost in Ulster for four centuries following the earldom's collapse.
The town is also defined geographically and administratively as a barony, a civil parish, and a townland covering 65 acres. According to the 2021 census, Carrickfergus had a population of 28,141.