That interior detail matters: a raised triangular platform, roughly 18 metres by 8 metres, sits pressed against the bank in the southeast sector, and a shallow circular hollow persists in the southwestern part. That hollow is the point. It marks, or rather marks the absence of, what was once believed to be the grave of Oisín, the warrior-poet of Irish mythology.

A ringfort, sometimes called a rath, is an enclosed farmstead of the early medieval period, typically consisting of a circular earthen bank with an outer ditch, or fosse, protecting a domestic interior. This one measures roughly 44 metres across north to south and 46 metres east to west, with a bank between five and six metres wide and an external fosse, now largely infilled on the eastern and southern sides but still faintly traceable elsewhere. By 1839, when Ordnance Survey fieldworkers were gathering local knowledge for what became the OS Letters, the site was already carrying a second name, Rath Oisín, shared with a related monument about 500 metres to the north-northeast. The name came with a story: two upright standing stones had marked the grave of the hero-bard within the enclosure, standing several yards apart. They were gone by the time the OS collector O'Flanagan recorded the account, removed by, in the memorable phrasing of his local informant, "some wicked man who had not the fear of Oisinn or the fairies before his eyes, but he died since, tho' not very old." The grave had also been dug up before that by "money dreamers," the period term for people who excavated ancient sites in the hope of finding buried treasure. What remained in 1839 was the circular hollow, and the hollow is apparently still there.

The original entrance to the rath was probably in the southern sector, where a gap about six metres wide survives, though it has been widened over time. Modern gaps have also been cut through the bank on the north and west sides. The land drops away to the east, and views open out in most directions from the slight elevation of the ridge's end, which may be part of why whoever built it chose the spot in the first place.