The rath at Corbally measures around 38 metres in diameter and retains its inner bank, the fosse or defensive ditch between it and the outer bank, and even traces of that outer bank on its south-western side, a degree of preservation that makes it a useful place to read exactly how these structures were originally layered. A causewayed entrance survives on the southern side, where the ditch was left uncut or subsequently filled to allow passage, giving a clear sense of how the enclosure was designed to be entered on deliberate, controlled terms.

Raths, sometimes called ringforts, were the dominant form of rural settlement in early medieval Ireland, built and occupied roughly between the fifth and twelfth centuries. They served as enclosed farmsteads, the banks and ditches less a military fortification than a boundary that kept livestock in and wolves or opportunistic raiders out. What makes Corbally particularly interesting is the souterrain recorded within the western sector of the interior. A souterrain is an underground stone-lined passage or chamber, typically constructed during the same early medieval period, and used for cool storage of dairy produce or, in times of threat, as a refuge. Their presence within a rath is common enough to suggest a standard feature of the wealthier farmstead, though the effort involved in their construction was considerable. That both the surface earthworks and the subterranean element survive here gives the site an unusual degree of stratigraphic legibility, the various phases of daily and defensive life still readable in the ground.