Sligo (slĪˈgō) [key], county (1991 pop. 54,756), 694 sq mi (1,797 sq km), N Republic of Ireland. The county seat is Sligo. The irregular coast line is deeply indented by Killala Bay and Sligo Bay. The interior is mountainous, with the Slieve Gamph, or Ox Mts., in the west and the Dartry range, rising to c.2,000 ft (610 m) in the northeast. Cattle raising (beef and dairy) is the chief occupation. Tourism is economically important. The population is less than one third of what it was before the potato famine of the mid-19th cent. A round tower at Drumcliffe is all that remains of a monastery founded by St. Columba in 575.