The enclosure measures roughly 28.5 metres across at its widest and is defined by a low scarp, a term for the steep face of an earthen bank or slope, running between two and three and a half metres wide and rising less than a metre in height. Around its perimeter, faint traces of an outer fosse, or defensive ditch, can still be detected, suggesting this was once a more substantial enclosure than its modest present appearance implies.

Sites of this kind, broadly classed as ringforts or similar enclosed settlements, are among the most common archaeological monuments in Ireland, with thousands recorded across the island. They were typically built and occupied during the early medieval period, roughly between the fifth and twelfth centuries, and served as farmsteads, sometimes with defensive intent and sometimes simply as boundary markers of status and land ownership. The hillock setting at Newcastle is characteristic, as elevated ground offered both visibility and a degree of natural advantage for the enclosure's builders. Without excavation, it is not possible to say more about who built this particular example or when it was in use, and no original entrance has been identified on the surface.