Gaer Llwyd is a trapezoidal enclosure, narrowing slightly on south side where it borders a steep promontory slope. On the north and west sides the enclosure is bounded by reasonably level ground. The enclosure ramparts are partly fossilised within field boundaries on the south and east sides, while the remainder of the enclosure has probably been intermittently ploughed in the past. Aerial photographs taken in winter 2002 show denuded earthworks of longer boundaries linked to the defended enclosure. The first leaves the north-west angle of the enclosure and runs west through the field. The second runs north from the same angle, and appears to have once been defined by a ditch and bank. Both boundaries could result from a later division of this hilltop into fields, but they could concievably also have origins in the prehistoric period. The first boundary is not shown on the County Series OS map; the second is shown as a boundary between cleared and uncleared pasture, but not as a firm boundary.

Aerial photographs (2002/5095-65) appear to show relict field boundaries connected to, and in vicinity of, the hillfort which could in part be contemporary.

T. Driver, 16 October 2007.