Among its many passage tombs, the monument recorded as National Monument No. 153 sits within this remarkable cluster, where the dead were brought and commemorated across an enormous span of prehistoric time. A passage tomb is a particular type of megalithic structure in which a narrow stone-lined corridor leads to a central burial chamber, the whole originally covered by a cairn of stones or earth. What makes Carrowmore as a complex so quietly compelling is the sheer density of monuments and the evidence that some of them predate even the famous passage tomb cemetery at Newgrange in the Boyne Valley.

The scholarly foundation for understanding this site comes largely from Seán Ó Nualláin's Survey of the Megalithic Tombs of Ireland, Volume V, published by the Stationery Office in Dublin in 1989, which documented the County Sligo monuments in systematic detail. Carrowmore had attracted antiquarian attention long before that, but Ó Nualláin's survey gave the complex a rigorous modern framework. The tombs here are generally smaller than those at Newgrange or Knowth, with many consisting of a simple boulder circle surrounding a dolmen-like central chamber, yet radiocarbon dates obtained from several of the Carrowmore monuments place some of them among the earliest megalithic constructions anywhere in Ireland, potentially dating to the late fifth or early fourth millennium BC. The central chamber visible in photographs taken from the north-west gives a clear sense of the construction method, with large orthostats, meaning upright stone slabs, defining the burial space.