A passage tomb is exactly what the name suggests: a burial chamber, typically stone-built, reached by a narrow stone-lined corridor and covered by a cairn or mound. What makes Carrowmore unusual is the sheer density of these monuments in a relatively small area, and the evidence that some of them pre-date even the famous passage tombs of the Boyne Valley.

The tomb has been catalogued and described by Seán Ó Nualláin in the fifth volume of the Survey of the Megalithic Tombs of Ireland, published by the Stationery Office in Dublin in 1989, which remains a key reference for the megalithic monuments of County Sligo. The site carries the name Petrie tomb no. 27, a designation reflecting the earlier antiquarian work of George Petrie, the nineteenth-century Irish scholar who contributed to some of the first systematic attempts to record Ireland's ancient monuments. The tomb is a National Monument in State care, protected under Irish heritage legislation.