This Norman fortification consists of a steep-sided circular mound, approximately 30 metres across at its base and rising 5 metres high, though quarrying has unfortunately removed the western portion. The motte’s summit was originally a flat platform about 12 metres in diameter, designed to support a wooden tower or keep. Between the motte and the adjoining bailey to the east, a defensive ditch or fosse once provided additional protection, though it’s now almost completely filled in.

The bailey, which served as the fortified courtyard where daily activities took place, forms a roughly rectangular enclosure measuring about 35 metres north to south and 20 metres east to west. A substantial earthen bank surrounds this space, with an external fosse that provided the primary line of defence; this ditch has been filled in on the northern side over the centuries. A low counterscarp bank, essentially a raised earthwork, follows the outer edge of the fosse, adding an extra defensive layer to the complex. Just 100 metres to the southeast stands Moybolgue Church, suggesting this area held considerable importance during the medieval period.

This impressive earthwork has been recognised as a national monument under the National Monuments Act 1930, acknowledging its archaeological, historical and architectural significance. The site represents the Anglo-Norman influence in medieval Ireland, when these motte and bailey castles served as both military strongholds and administrative centres for newly conquered territories. Though time and human activity have altered its original form, the earthworks at Relagh Beg remain a tangible link to Ireland’s complex medieval past.