added by archaeologs The site of prehistoric ritual monuments and Neolithic passage graves in the valley of the River Boyne, Ireland, dating to the 4th millennium BC. The complex includes five henges, a number of mounds, and the three great passage graves of Newgrange, Dowth, and Knowth. These megalithic tombs are set in round mounds and usually set on hilltops or grouped in cemeteries. These structures are notable for their size, their decoration, and the architectural expertise involved. The term 'Boyne culture' is sometimes used to describe the material found inside passage graves all over Ireland. Its characteristics are highly decorated Carrowkeel style of pottery, bone pins with poppy- or mushroom-shaped heads, pendants, and beads.