3, a structure that has been sitting quietly in this landscape for several thousand years while the world around it changed beyond recognition. Passage tombs are a specific type of megalithic monument in which a stone-lined corridor, or passage, leads into a central burial chamber, typically covered by a cairn of earth and stone. What makes Carrowmore unusual even by megalithic standards is the sheer density of monuments gathered within a relatively compact area, each one part of a wider ceremonial landscape that clearly mattered enormously to the communities who built it.

The tomb is identified in the literature by the name Petrie, a reference to the nineteenth-century antiquarian George Petrie, whose early documentation of Irish monuments helped establish a numbered system still used in the field today. The most detailed modern account of this particular structure appears in Seán Ó Nualláin's Survey of the Megalithic Tombs of Ireland, Volume V, covering County Sligo, published by the Stationery Office in Dublin in 1989. That volume remains a key reference for anyone trying to understand the full extent and variety of the Carrowmore complex. The tomb is now a National Monument in State care, which means it enjoys formal legal protection and is managed as part of the broader Carrowmore site.