This earthwork fortress, known historically as the castle of Magh Breacruighe (or Moybrekry), once belonged to John de La Mare, an Anglo-Norman lord who held the property in the late 13th century. The castle’s turbulent history is well documented in the Annals of the Four Masters, which record that it was “razed to the ground” by Geoffrey O’Ferrall in 1295, marking just the beginning of centuries of conflict over this strategic position.

The impressive motte rises seven metres high with a base diameter of approximately 42 metres, its steep sides still showing evidence of external stone facing where mortared stones protrude through the earthen slopes. The summit, measuring 14 metres across with a slightly concave profile, reveals traces of mortared stone around its perimeter, suggesting the presence of an enclosing wall or defensive structure that once crowned the artificial hill. Below, a fosse or defensive ditch, ranging from five to seven and a half metres wide, encircles the base of the mound, whilst the degraded remains of a rectangular bailey, roughly 30 by 21.5 metres, can still be traced as a low rise of ground to the southeast.

The site’s violent past continued well into the 15th century. In 1455, what the Annals call ‘Caislen-na-Sraide’ (castle of the street) was demolished by O’Farrell, who killed Mac Herbert’s son whilst taking the fortification, though historians debate whether this refers to a stone castle built atop the motte or to a second, unidentified castle elsewhere in Street village. The wider settlement suffered further destruction in 1464 when Baron Delvin burnt the ‘Sraid of Moybrecray’, destroying both churches and houses during the bitter conflict between the Nugents and Herberts. Today, the tree-covered mound stands peacefully 135 metres northwest of the local church and graveyard, a quiet reminder of the centuries of Anglo-Norman and Gaelic warfare that once raged across this part of the Irish midlands.