The enclosure measures just under 25 metres across at its widest, and while that is modest by any standard, the form itself belongs to a category of monument that once dotted the Irish landscape in its thousands. These ringforts, or raths, were the farmsteads and enclosed settlements of early medieval Ireland, typically dating from around the fifth to the twelfth century, though some are considerably older. What survives at Tireran is the earthen bank that once defined the perimeter, now reduced in places to little more than a low scarp, the slight ridge left when a bank has eroded and spread over centuries. Along the outer edge, traces of a fosse remain, the shallow ditch from which the bank material was originally dug.

The bank survives most clearly along the southern, western, and northern arc, while elsewhere it has been worn down almost level with the surrounding ground. There are gaps at several points, on the south, south-south-west, west-north-west, and north-west, but none of these can be confidently identified as the original entrance. It is a common problem with sites of this kind; later field boundaries, animal passage, and simple erosion tend to create breaks that are impossible to distinguish from deliberate openings without excavation. The drumlin setting is also characteristic of this part of Ulster, where the rolling, hummocky landscape shaped by the last glaciation gave early farmers both elevated ground and good drainage, two qualities that appear to have guided where these enclosures were built again and again across counties like Monaghan.