An ancient earthwork enclosure does not usually come in triangles. Most Irish examples, whether prehistoric ringforts or early medieval enclosures, follow the logic of a circle, that being the most efficient shape for defending a central space with the least length of bank. The enclosure at Knockpatrick in County Kildare breaks that convention, presenting instead a roughly triangular outline, its bank enclosing a space of around seventy metres at its widest point. Whether the shape reflects the original plan of whoever built it, or whether it simply accommodated the contours of the slope on which it sits, is not recorded.

The site was noted on the Ordnance Survey six-inch map of 1907, already settled into a wooded area that appears at some point to have seen quarrying. That combination, ancient earthwork and later quarrying in close proximity, makes the survival of the bank all the more unexpected. It stands to roughly one and a half metres on the outer face, and rises to about two and a half metres on the inner side, the difference a direct consequence of its position on a slope rather than flat ground. The western section is the best preserved. A 1955 survey by Danaher recorded a shallow fosse, cut into the rock, running outside the bank, and identified what appeared to be a circular house site in the south-eastern part of the interior. A fosse is simply a ditch, in this case carved directly into bedrock rather than dug through soil, which suggests both the effort invested in the original construction and the nature of the ground beneath. The circular house site hints at domestic occupation, the kind of enclosed farmstead common in early medieval Ireland, though nothing in the available record pins the enclosure to a specific period or people.