Sligo (Sligeach in Irish) is a county in the province of Connacht in the west of Ireland. Sligo's Irish name - meaning "the place of shells" - comes from the fact that there was an abundance of shellfish in the river and its estuary. The river (now known as the Garavogue) was originally also called the Sligeach. The Ordnance Survey letters of 1836 state that "cart loads of shells were found underground in many places within the town where houses now stand". At that time shells were constantly being dug up during the construction of foundations for buildings. This whole area, from the river estuary of the "Shelly River", around the coast to the river at Ballysadare Bay was rich in marine resources and was a prime reason for large settlement of the region during the prehistoric period.

The poet and Nobel laureate W. B. Yeats (1865-1939) spent much of his childhood in northern Sligo and the county's landscapes (particularly the Isle of Inisfree, in Lough Gill) were the inspiration for much of his poetry. Yeats said, "the place that has really influenced my life most is Sligo."