This ancient fortification, possibly dating back to prehistoric times, spans approximately 370 metres from east to west and appears to have been constructed with remarkable ingenuity, incorporating the hill's natural rock outcrops into its defensive design. The builders cleverly scarped existing geological features on the western side, whilst constructing more traditional earthen banks and ditches on the eastern approach where the land meets modern forestry plantations.

The hillfort's construction reveals sophisticated planning, with what may be three concentric rings of defences; a trivallate design that would have made it formidable in its day. These defensive circuits follow the natural contours of the hill, with bands of rock outcrop particularly visible on the southwest and western faces forming natural barriers. Within this extensive fortification sits a smaller circular enclosure at the summit, connected by two linear features that stretch southeast to meet the outer defences. Radiating from the inner enclosure are the remnants of meandering drystone field walls, possibly contemporary with the fort itself, suggesting this was once a thriving agricultural centre as well as a defensive stronghold.

The site holds layers of history beyond its Iron Age origins. St Brigid's holy well sits below the southern summit, marking the hill's continued spiritual significance through the centuries, whilst the name 'Cashel' within the fort refers to a later stone structure built within the ancient defences. Aerial photography from both 1964 and 2011 reveals the monument's impressive scale and preservation, with the ramparts still clearly visible as they curve around the hilltop. Today, cattle graze peacefully within the fort's interior, where ancient field systems once supported a community that chose this commanding height to make their home and defend their territory.