From its elevated position, the site overlooks a west to east stretch of the River Blackwater roughly 700 metres to the north. Whilst an inland lighthouse built in 1791 now dominates the hilltop, along with some later landscape features, archaeological investigation has revealed that this location has been significant for millennia.

In 2013, the Discovery Programme conducted geophysical surveys as part of their 'Late Iron Age and "Roman" Ireland' project, which revealed the complex defensive architecture hidden beneath the surface. The survey identified a summit enclosure approximately 120 metres in diameter, defined by two ditches with accompanying inner banks and what appears to be a burnt palisade trench. An entrance gap through these features faces east. Beyond this central fortification, at a distance of 70 to 80 metres, lies an outer enclosure measuring about 250 metres across, created by at least two earlier fosse features that are now partially obscured by later earthworks. Between these two defensive circuits, archaeologists detected several uncertain ring ditches, including one interrupted fosse feature about 22 metres in diameter, positioned east of the summit enclosure's entrance.

Test excavations conducted in 2003 uncovered what may be a pit or ditch associated with the summit enclosure. Radiocarbon dating of burnt animal bone from this feature provided a date range of 1130 to 910 BC, placing the site's occupation firmly in the Late Bronze Age. This dating evidence, combined with the sophisticated defensive layout revealed by geophysical survey, demonstrates that the Commons of Lloyd hillfort was an important fortified settlement during a period of significant social and technological change in prehistoric Ireland.