Carlow, town (1991 pop. 14,027), seat of Co. Carlow, SE Republic of Ireland, on the Barrow River. It is an agricultural market in a dairy region, with sugar refining, flour milling, brewing, and shoe manufacturing. There are ruins of a 12th-century castle. The town is also the seat of the Roman Catholic diocese of Kildare and Leighlin. Of strategic importance, Carlow was burned in 1405 and in 1577. In 1798 a fierce street battle was fought there by insurgent United Irishmen. St. Patrick's College for priests opened in 1798.