This ancient fortification spans an impressive 28.1 hectares, making it one of the larger examples of its type in the country. The site consists of multiple enclosures that follow the natural contours of the domed summit, with the innermost defensive ring measuring approximately 112 metres in diameter. What survives today is a massive earthen bank, roughly 10.6 metres wide and still standing up to 3.5 metres high on its inner face, accompanied by an external fosse or ditch that runs around most of the perimeter, save for a gap at the northeast.

The hillfort's defensive architecture tells a story of considerable planning and labour. The inner rampart remains remarkably well preserved throughout its circuit, whilst traces of what may have been an outer enclosing element can still be seen as a curving field boundary to the west, suggesting the site was once even more extensively fortified. A possible entrance appears to have been positioned at the east-southeast, and intriguingly, a natural spring emerges within the eastern section of the ditch; a water source that would have been invaluable to the fort's ancient inhabitants. Despite its size and the effort that went into its construction, no evidence of internal structures has been detected on the surface, leaving questions about how the interior space was utilised.

Today, the hillfort's interior is given over to pasture with scattered tree cover, a peaceful scene that belies its defensive past. First identified on Ordnance Survey maps in the 19th century, the site has been subject to archaeological survey work, most notably by Sweetman and colleagues in 1995. While much about Boley Hill remains mysterious, including its exact date of construction and the identity of its builders, it stands as a remarkable example of prehistoric engineering and community organisation in ancient Ireland, where considerable resources were marshalled to create these monumental defensive structures that still dominate the landscape thousands of years later.