A ringfort, or rath, is a roughly circular enclosure typically built during the early medieval period in Ireland, used as a farmstead and defended residence. This one at Knockane measures approximately 26 metres east to west and 24 metres north to south, its interior defined by an earthen bank that still rises about 1.6 metres on the inside and a more imposing 3 metres on the exterior. A fosse, the external defensive ditch, runs from the north-west to the east and reaches a depth of 1.6 metres, though the north-western section has been partly filled in over the centuries with field clearance stones.

What makes this fort particularly worth examining is the quality of surviving detail at its eastern entrance, which is just 1.3 metres wide. Upright contiguous slabs, ranging from 0.6 to 0.9 metres in length and standing roughly 0.8 metres high, line both sides of the gap, forming a stone revetment that stabilises the earthen bank at its most vulnerable point. On the southern side, a row of these stones is now almost free-standing, the original bank having been largely replaced by a later stone field boundary that curves outward just before it reaches the entrance. That interplay of original early medieval construction and subsequent agricultural modification is visible throughout the site. The interior still carries the faint corrugations of cultivation ridges running on a north-south axis, and a roughly square raised area of about 7 by 8 metres sits in the north-west quadrant, lifted some 0.3 metres above the surrounding ground level, its original function unclear but its regularity suggestive of deliberate construction rather than accidental accumulation.