It measures approximately 38 metres east to west and 36 metres north to south, making it a fairly typical example of the rath, the earthen ringfort that was once the standard unit of rural settlement across early medieval Ireland. A rath usually consisted of a raised circular bank enclosing a family farmstead, with the bank and its accompanying ditch serving as much as a social marker as a defensive one.

What survives at Caherdrinny is a slightly eroded version of that form. The enclosing bank still stands to around 0.8 metres on the interior and 1.1 metres on the exterior, with an external fosse, a shallow ditch, reaching about half a metre in depth. From the northeast around to the west-southwest the bank is most clearly defined, while elsewhere the boundary survives as a scarp, a simple slope in the ground rather than a built-up ridge. There are numerous breaks in the bank, the kind of incremental damage that accumulates over centuries of agricultural use, as gaps are opened for livestock, field drains cut through, and the earthwork slowly cannibalised for surrounding ground. A second bank visible to the northwest appears to be the remains of a later field boundary rather than an original feature of the ringfort. The interior slopes gently downward toward the northwest, a small topographical detail that would have mattered to whoever originally chose and shaped the site.

Sites like this one reward a certain kind of attention. The earthworks are subtle enough that from a distance the field looks unremarkable, but once you are standing at the bank, the geometry of the enclosure becomes clear, and the sense of a deliberate human arrangement, someone's home ground, reasserts itself through the grass.