The monument consists of a fairly high, steep-sided mound with a flat top measuring about 13 metres across. Around its base runs a defensive ditch, or fosse, with traces of an outer earthen bank that’s best preserved along the western and northern sides. Whilst officially designated as a motte, some archaeologists suggest this could actually be a platform-type ringfort that was later repurposed as a Norman fortification.

The site shows clear signs of its long history and various uses over the centuries. An old roadway once ran past the northern base of the motte; whilst no longer in use, its outline appears on the 1837 Ordnance Survey map and can still be spotted in aerial photographs from 2011. The summit, now home to an Ordnance Survey triangulation station, shows considerable disturbance from centuries of use and natural erosion. The defensive fosse has been filled in along the southern and south-western sections, and a modern field fence cuts through the badly damaged outer bank in the same area. There’s also a modern gap in the north-western sector and traces of what appears to be a recent causeway crossing the fosse to the south.

Adding to the site’s mystery, a wide, low bank extends eastward from near the southern side of the earthwork, though its original purpose remains unclear. Just 250 metres to the north-west stands a building marked as ‘Coolnagun Castle’ on the 1911 Ordnance Survey map, suggesting this area has long been associated with defensive structures. Very faint traces of an old field bank can also be detected running east to west outside the monument’s northern edge, another reminder of the landscape’s agricultural past.