County Down

County Down (Irish: Contae an Dúin) 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.

In the east of the county is Strangford Lough and the Ards Peninsula. The largest settlement is Bangor, a city on the northeast coast. Three other large towns and cities are on its border: Newry lies on the western border with County Armagh. Lisburn and Belfast lie on the northern border with County Antrim. Down contains the southernmost point of Northern Ireland (Cranfield Point) and the easternmost point of Ireland (Burr Point).

It was one of two counties of Northern Ireland to have a Protestant majority in the 2001 census. The other Protestant-majority County was County Antrim to the north. In the 2021 Census, it was the only county with a Protestant background majority, as Antrim has a Protestant background plurality. In the 2021 census, Ards and North Down had the highest number of "No Religion" responses (30.6%) for Northern Ireland.

In March 2018, The Sunday Times published its list of Best Places to Live in Britain, including five in Northern Ireland. The list included three in County Down: Holywood, Newcastle, and Strangford.

The county has two cities: Newry and Bangor. Bangor is the more recent, gaining city status in December 2022.

County Down takes its name from dún, the Irish word for dun or fort, which is a common root in Gaelic place names, such as Dundee, Dunfermline and Dumbarton in Scotland and Donegal and Dundalk in the Republic of Ireland. The fort in question was in the historic town of Downpatrick, originally known as Dún Lethglaise ("fort of the green side" or "fort of the two broken fetters"). Another word for the county is "Downshire".

In the 2nd century the region was home to the Voluntii tribe, according to Ptolemy. From the 400s–1177 County Down formed a central part of the kingdom of Ulaid. Ulaid was a frequent target of Viking raids in the eighth and ninth centuries. Fierce local resistance prevented the Norse from setting up permanent settlements in the region. In 1001, a fleet led by Sigtrygg Silkbeard raided much of the region in retribution for the Ulaiden's refusal to offer him sanctuary from Brian Boru the previous year.

The region was invaded by the Normans in 1177. From the 1180s–1600s the region saw waves of English and Scottish immigration. In 1569, the Irish Parliament passed "An Act for turning of Countries that be not yet Shire Grounds into Shire Grounds". In 1570, a commission was issued in pursuance of that statute "to survey and make enquiry in the countries and territories ... that are not shire ground, or are doubtful to what shire they belong; to limit and nominate them a shire or county; to divide them into countries, baronies or hundreds, or to join them to any existing shire or barony" "for the countries or territories of Arde, as well this side Blackstafe as the other side, Copelande islands, the Dufferin, Clandeboy, Kilultoghe, the Glynes with the Raughlines, Momerie and Carie, the Rowte M'William (McQuillan) and all lands between lough Coine and lough Eaghe, and the water of Strangforde and the Banne. To certify their proceedings before the 1st August."