County Antrim (named after the town of Antrim, ) is one of six counties of Northern Ireland and one of the thirty-two counties of Ireland. Adjoined to the north-east shore of Lough Neagh, the county covers an area of and has a population of 651,321, as of the 2021 census. County Antrim has a population density of 203 people per square kilometre or 526 people per square mile. It is also one of the thirty-two traditional counties of Ireland, as well as part of the historic province of Ulster.
The Glens of Antrim offer isolated rugged landscapes, the Giant's Causeway is a unique landscape and a UNESCO World Heritage Site, Bushmills produces whiskey, and Portrush is a popular seaside resort and night-life area. The majority of Belfast, the capital city of Northern Ireland, is in County Antrim, with the remainder being in County Down.
According to the 2001, 2011, and 2021 censuses it is currently one of only two counties of the Island of Ireland in which a plurality or majority of the population are from a Protestant background. The other is County Down to the south.
A large portion of Antrim is hilly, especially in the east, where the highest elevations are attained. The range runs north and south, and, following this direction, the highest points are Knocklayd , Slieveanorra , Trostan , Slemish , Agnew's Hill and Divis . The inland slope is gradual, but on the northern shore the range terminates in abrupt and almost perpendicular declivities, and here, consequently, some of the finest coast scenery in the world is found, widely differing, with its unbroken lines of cliffs, from the indented coast-line of the west. The most remarkable cliffs are those formed of perpendicular basaltic columns, extending for many miles, and most strikingly displayed in Fair Head and the celebrated Giant's Causeway. From the eastern coast the hills rise instantly but less abruptly, and the indentations are wider and deeper.