The structure at Castlecarragh consisted of an impressive earth and stone mound, originally measuring about 30 metres across at its base and rising to approximately 5 metres in height. Around its eastern side, archaeologists identified traces of a wide defensive ditch, or fosse, that would have been about 8 metres wide and a metre deep; now filled in by centuries of soil accumulation.

The motte’s position on elevated ground at the edge of an ancient river valley suggests its builders chose the location carefully for its defensive advantages. The western side of the mound shows signs of having partially collapsed into the old river valley below, which may have been where the Castletown River originally flowed before changing its course over time. This kind of natural erosion is common with earthwork fortifications built near waterways, as the combination of weather and shifting river patterns gradually undermines their foundations.

Unfortunately, this piece of medieval heritage met an inglorious end around 1979 when the site was quarried out and destroyed. Before its destruction, it was documented by Morris in 1906 and later included in both the Archaeological Inventory of County Louth (1986) and the Archaeological Survey of County Louth (1991). These surveys remain the primary sources for understanding what this Norman fortification once looked like and its role in the medieval landscape of Louth.