Beginish lies in Valencia Harbour, positioned between Valencia Island and the mainland, and at certain low tides its south-eastern sandbar connects it to the neighbouring Church Island. On the island's highest ground, a promontory called Canroe, the remains of an entire settlement spread across the summit and down towards the rocky eastern shoreline: eight houses, fifteen cairns, eight animal shelters, and a web of fields and enclosing walls, with an iron smelting site at the western end. What survives is not a ruin in the romantic sense but a legible pattern of occupation, the physical trace of people who farmed, smelted metal, and sheltered animals on this exposed Atlantic outcrop.

Archaeologist M. J. O'Kelly excavated two of the houses, a cairn, and an animal shelter here in the early 1950s, publishing his findings in 1956. One of the excavated structures, a circular house roughly 6.5 metres across internally, proved to have walls that may once have reached 2 metres in thickness, though almost all the dressed facing stones had been robbed out at some point, presumably reused elsewhere on the island. The narrow entrance, just 0.7 metres wide and framed by two upright jambstones, faced south-east. More intriguing still, excavation exposed a smaller inner structure built directly from the stolen facing stones of the original house, meaning it was constructed after the larger building had already been partly demolished. That inner structure was itself subsequently stripped of its facing slabs. No domestic refuse was found inside, and O'Kelly interpreted the whole arrangement as an animal shelter or enclosure rather than a dwelling. The sequence of construction, robbing, and rebuilding within a single footprint says something about the practical, unsentimental approach early medieval islanders took to their limited building materials.