Civil parishes in Ireland are based on the medieval Christian parishes, adapted by the English administration and by the Church of Ireland.[1] The parishes, their division into townlands and their grouping into baronies, were recorded in the Down Survey undertaken in 1656-58 by surveyors under William Petty. The purpose was primarily cadastral, recording land boundaries and ownership.[2] The civil parishes are not administrative units. They differ from Catholic parishes, which are generally larger.[1]