Known as Dún Kilmore on Ordnance Survey maps, this is not a simple promontory fort, where a single wall cuts a headland off from the land behind it, but something considerably more elaborate: an irregularly shaped headland roughly 290 metres by 120 metres, enclosed by earth and stone defences, and containing within it two further defended subsidiary headlands, a ringfort, hut sites, and a children's burial ground. The layering of these elements into a single complex is unusual enough to make the site one of the more quietly remarkable pieces of early Irish coastal archaeology on the west coast.

The outermost line of defence consists of a curving stone wall set upon an earthen bank, with a fosse, or external ditch, running along its outer face. The wall still stands to around a metre in height in places, and a gateway near the northern cliff edge, just under a metre wide and over a metre high, remains clearly defined, with large limestone slabs nearby that may be the collapsed remains of the door jambs or lintel. When the antiquarian Thomas Johnson Westropp recorded the site in his 1912 survey, he described a bank nine feet high with revetting surviving to ten feet; what remains today is considerably reduced. Inside the main enclosure, the two subsidiary headlands, marked on OS maps as the Dangan to the north and the Dun to the south, are each cut off by their own ditches and banks. Within the berm of the Dun's defences lies a low circular stone structure, nine metres in internal diameter, whose form and position recalls the Scottish broch or blockhouse tradition, a rare and provocative comparison for a Mayo site. The large ringfort in the eastern part of the enclosure, some 70 metres in internal diameter, contains a children's burial ground with small cist-like graves marked by plain limestone slabs, an altar piled with white quartz pebbles, a bullaun stone (a boulders with a carved basin-shaped hollow, often associated with early Christian sites), and a rectangular structure that may be the remains of the small church from which the headland takes its name.