The site forms an approximately square enclosure, measuring roughly 40 metres from east to west, with remnants of defensive features still visible despite centuries of erosion. Low earthen banks mark the southern, western and northern boundaries, whilst faint traces of what was once a fosse, or defensive ditch, can still be detected by those who know where to look.

The entrance to this medieval fortification has been lost to time, leaving archaeologists to speculate about how residents and visitors once accessed the enclosure. What makes this particular site intriguing is its position right along the county boundary; the southern limits of the monument appear to follow the border between County Kildare and County Carlow so precisely that heritage authorities have given it dual designation, recognising its significance to both counties.

These moated sites, which dot the Irish landscape, were typically constructed between the 13th and 14th centuries by Anglo-Norman settlers or prosperous Irish families. They served as defended homesteads, with the earthen banks and water-filled ditches providing both practical defence and a display of status. Though this particular example at Ballyraggan may appear modest today, it once would have enclosed timber buildings, perhaps a hall house and associated structures, creating a self-contained farmstead that balanced agricultural productivity with defensive capability.