On the Ordnance Survey six-inch sheet from 1842, the enclosure reads as circular, the classic form expected of a rath. By 1905 and again in 1937, the same surveyors' conventions produce a noticeably oval outline. The shape had not changed so much as the ground had, altered by quarrying that bit into the southern and western edges and left the enclosure slightly lopsided, its original geometry only partially recoverable.

A rath, or ringfort, is an enclosed farmstead of the early medieval period, typically dating from roughly the fifth to the twelfth century, defined by one or more earthen banks and ditches and used as a defended residence for a farming family and their livestock. The example at Egmont sits on a south-facing slope in pasture, positioned above a pronounced fall of ground to the south that has itself been quarried. The enclosure measures roughly 43 metres east to west and 36.3 metres north to south. To the north, a heavily overgrown earthen bank survives, standing about 0.6 metres on the interior face and 0.8 metres on the exterior. To the east, south, and west, the boundary takes the form of a scarp rather than a built bank, and an external fosse, a defensive ditch, survives to the west and north at a depth of around 0.65 metres. The interior slopes downward toward the southeast, and the southern scarp is obscured by overgrowth, possibly cut back by quarrying activity that also affected the southeastern and western portions of the site. What quarrying did not damage, vegetation has done its best to conceal.