The enclosure recorded at Dún Sheáin, on the Dingle Peninsula in County Kerry, is a quiet exception. Rather than the expected round outline, the first-edition Ordnance Survey map shows a univallate enclosure, meaning one defined by a single bank and ditch, that is vaguely sub-rectangular in plan. It sits in level, wet pastureland near the south-eastern edge of the Trabeg inlet, a small coastal indentation on the northern side of the peninsula.

The detail comes from J. Cuppage's 1986 archaeological survey of the Corca Dhuibhne region, a thorough study of the Dingle Peninsula that catalogued hundreds of monuments across the area. The sub-rectangular outline is unusual enough to be worth noting; while ringforts do occasionally deviate from a strict circle, a more angular form can sometimes suggest that the enclosure was adapted to the lie of the land, or that it served a purpose slightly different from the typical defended farmstead of the early medieval period. The wet, low-lying ground near the inlet would have shaped whatever activity took place here, and the proximity to the coast places it within a landscape that was economically and socially active throughout the early centuries of the first millennium.