What makes the site quietly arresting is that the excavation, however rough, has left the internal architecture exposed: you can see the actual gallery of the tomb rather than simply a grass-covered heap.

This is a wedge tomb, a type of megalithic burial monument that appears across Ireland, generally dating to the late Neolithic and early Bronze Age, roughly 2500 to 2000 BC. Wedge tombs typically consist of a roofed stone gallery, wider and higher at one end and tapering toward the other, set within a cairn of smaller stones. At Blackrock, the cairn measures approximately twelve metres by ten metres, rising to a maximum height of around 1.8 metres. On its western side, a kerb of upright stones forms what is described as a flattened facade, four kerbstones of which remain visible. The exposed gallery inside runs to about six metres in length and 1.8 metres in width, defined by two sidestones, three outer wall stones, and a buttress stone. There is also evidence of internal walling surviving on the southern side of the cairn, suggesting the structure was more elaborate in its original form than what remains today. The site was recorded and described by the archaeologist Seán Ó Nualláin in 1989, whose systematic survey of Irish wedge tombs remains a key reference for monuments of this type.