The site measures approximately 55 metres from northwest to southeast and varies in width from 40 metres at its northwestern end to 50 metres at the southeastern edge, creating a distinctive trapezoidal footprint. What makes this structure particularly interesting is its sophisticated defensive design; the northwestern and southwestern sides feature an earthen bank standing 1.5 metres high with vertical stone facing on both the inner and outer walls, accompanied by an external flat-bottomed fosse, or defensive ditch, that’s 2 metres wide and nearly a metre deep.

The southeastern boundary takes advantage of the natural topography, incorporating a steep scarp that drops 1.6 metres with another fosse running along its base, whilst the northeastern side has been modified over time and now follows a modern field boundary. Despite careful archaeological survey, no clear entrance point has been identified, nor are there any visible internal features that might hint at the site’s original layout or function. The stone facing that extends down to the base of the external fosse suggests considerable effort went into the construction, indicating this was likely a site of some importance in its day.

Historical records add another layer of mystery to the site. The first edition Ordnance Survey 6-inch map, dating from the mid-19th century, marks a ‘Castle in ruins’ at the southeastern edge of the enclosure, though no above-ground traces of this structure remain visible today. Whether this refers to a stone castle that once stood within or adjacent to the earthwork, or whether the earthwork itself was considered the ‘castle’, remains unclear. The site’s location in Castlequarter certainly suggests a long-standing association with fortification in local memory, even if the physical evidence has largely returned to the landscape.