The great cairn of Knocknarea is the largest and most visible neolithic monument in the west of Ireland. The huge monument, which was probably built between 3,500 and 3,200 BC, is part of the Irish passage-grave culture, which had arrived in Sligo from the shores of Brittany by around 4,150 BC. The oldest dated monument in Sligo is the very early causewayed enclosure at Magheraboy, between Carns Hill and the Carrowmore megalithic complex.
Queen Maeve’s cairn is the westernmost portion of this complex, situated close to the highest part of the flat top of Knocknarea, 327 meters above sea level. The enormous mound is about sixty meters in diameter, ten meters high, and is estimated to contain some 30,000 tons of stone, which was quarried closeby.