It is here, on that vertiginous edge, that someone chose to build a rath, a type of enclosed ringfort typically used as a farmstead and settlement during the early medieval period in Ireland. The river itself does part of the defensive work on the north-west side, its vertical bank forming a natural barrier, while the rest of the enclosure relies on an earthen bank and an external fosse, a defensive ditch, to complete the circuit.

What survives is unusually substantial. The fosse is straight-sided and flat-bottomed, reaching two metres below the external ground level with a basal width of around three metres, and its sides show partial stone-facing, though this may have been added at a later stage. The bank, revetted intermittently with drystone masonry both inside and out, rises to a maximum external height of five metres on the western side. The interior measures roughly 35 by 25 metres. At the south-east, a 4.3-metre-wide entrance is still traceable, with a much-disturbed causeway crossing the fosse at that point. The site may well be the same place recorded as 'Lisahan' in the Ordnance Survey Name Books, which were compiled in the nineteenth century as part of the first systematic mapping of Ireland, suggesting the name and the location were locally remembered even then. The archaeological survey of the Iveragh Peninsula, published by Cork University Press in 1996 and compiled by A. O'Sullivan and J. Sheehan, records the site in considerable detail.

The immediate surroundings are heavily wooded and the rath itself is overgrown, which makes it easy to miss but also lends the place a particular quality. The combination of dense vegetation, steep riverbank, and substantial earthworks creates an enclosure that feels genuinely apart from its surroundings, set off from the landscape rather than merely sitting within it.