In Great Britain and Ireland, a county town is usually the location of administrative or judicial functions within a county, and the place where public representatives are elected to parliament. Following the establishment of county councils in England in 1889, the headquarters of the new councils were usually established in the county town of each county; however, the concept of a county town pre-dates these councils. The concept of a county town is ill-defined and unofficial. Some counties in Great Britain have their administrative bodies housed elsewhere. For example, Lancaster is the county town of Lancashire, but the county council is in Preston. Due to the creation of unitary authorities, some county towns in Great Britain are administratively separate from the county. For example, Nottingham is separated from the rest of Nottinghamshire, and Brighton and Hove is separate from East Sussex. On a ceremonial level, both are in their own respective counties geographically.

Great Britain, historic

England

This list shows towns or cities which held county functions at various points in time.

Scotland

Wales

Following the Norman invasion of Wales, the Cambro-Normans created the historic shire system (also known as ancient counties). Many of these counties were named for the centre of Norman power within the new county (Caernarfonshire named for Caernarfon, Monmouthshire named for Monmouth) others were named after the previous medieval Welsh kingdoms (Ceredigon becomes Cardigan, Morgannwg becomes Glamorgan). The 1535 Laws in Wales Act established the historic counties in English law, but in Wales they were later replaced with eight preserved counties for ceremonial purposes and the twenty two principal areas are used for administrative purposes. Neither of these subdivisions use official county towns, although their administrative headquarters and ceremonial centres are often located in the historic county town.

Great Britain, post 19th-century reforms

With the creation of elected county councils in 1889, the administrative headquarters in some cases moved away from the traditional county town. Furthermore, in 1965 and 1974 there were major boundary changes in England and Wales and administrative counties were replaced with new metropolitan and non-metropolitan counties. The boundaries underwent further alterations between 1995 and 1998 to create unitary authorities, and some of the ancient counties and county towns were restored. (Note: not all headquarters are or were called County Halls or Shire Halls e.g.: Cumbria County Council's HQ up until 2016 was called The Courts and has since moved to Cumbria House.) Before 1974, many of the county halls were in towns and cities that had the status of a county borough i.e. a borough outside the county council's jurisdiction.

England, from 1889

England, from 1965

Wales

Ireland

Republic of Ireland

The follow lists the location of the administration of each of the 31 local authorities in the Republic of Ireland, with 26 of the traditional counties.

Northern Ireland

Note – Despite the fact that Belfast is the capital of Northern Ireland, it is not the county town of any county. Greater Belfast straddles two counties – Antrim and Down.

Jamaica

Jamaica's three counties were established in 1758 to facilitate the holding of courts along the lines of the British county court system, with each county having a county town. The counties have no current administrative relevance.