What sets this one apart is the detail revealed when its ditches were examined closely: the two outer fosses, the broad defensive trenches that encircle the fort, do not complete their circuit on the northern side. One might assume a later fort had simply cut through them, but excavation proved the opposite. The gaps were deliberate, built in from the start, because a neighbouring fort already occupied that ground.

The site sits within a large archaeological complex on what antiquarians including Thomas Johnson Westropp identified as the supposed site of Temaír Erann, the ancient cemetery of the Ernai tribe. The ringfort in question, designated Ringfort 5 of the Southern Group by the archaeologist Seán P. Ó Ríordáin, is bivallate, meaning it is defended by two banks and two ditches rather than one, and forms the southernmost of three conjoined ringforts. Ó Ríordáin excavated it between 1934 and 1935, and his findings, published in 1940, showed a site that had gone through several distinct phases of use. At its core was a fragment of dry-stone walling, the remnant of an early circular house built against bedrock cut back at the centre of the fort. Later occupation was marked by charcoal traces indicating the walls of wooden structures, at least one circular and one rectangular. Patches of paving survived at different levels, suggesting successive floors laid at different periods. A souterrain, an underground stone-lined passage typically used for storage or refuge, was recorded in the north-east quadrant. The fort was eventually abandoned as a place of habitation and repurposed as a burial ground; four urn and cist burials as well as cremated remains were found inside. By the time an enclosure was added to the wider complex, this fort had already been deliberately placed outside it, excluded from the group by the way the new fosse was connected up. Ó Ríordáin also noted a peculiar asymmetry at the entrance on the western side: the outer ditch narrowed to a drain barely 0.6 metres wide on one approach, suggesting that once a further fort was built nearby, full defensive depth on that side was no longer considered necessary.

The site lies within a wider complex on Slievereagh and is set in rough agricultural land, so stout footwear is advisable. The earthworks themselves are the main thing to look for: the double banks and the incomplete northern ditches, which reward attention once you know what the excavation revealed about why they were built that way. The surrounding field system and the remains of the conjoined forts to the north give a sense of how densely this ridge was once occupied and organised.