Sligo's Green Fort, was an ancient site of strategic importance for the defence of the town, is situated in the townland of Forthill which got its name from the Green Fort which was built here in 1646.
The Green Fort is a star-shaped (or quadrilateral) fort, covering almost an acre of land, which was built to protect Sligo Town during the Jacobite war between William of Orange and King James II, and remain's the only visible remnant of what was once a formidable fortification of Sligo Town.
The Green Fort occupies an elevated position, affording itself of good view's of the approaches to Sligo Town, from the North towards Benbulben to the South from Sligo Bay to Knocknarea and to the Ox mountains beyond.
The Green Fort consisted of a large bastion with a platform at each corner. Access to the interior was gained via two gates with the whole site surrounded by a large fosse, with banked and ditched defences running due west and south of the site.
