What remains today are fragments of the east wall, stretching approximately 7.4 metres, and a portion of the south wall measuring about 2.6 metres, both rising four storeys high despite their ruinous state. The structure appears on the 1563 map of Leix and Offaly, marking its significance during a turbulent period when the O’Moore clan erected it as a defensive position against incursions from the Pale, that fortified area around Dublin controlled by the English crown.

The castle’s story took a decisive turn in 1576 when Robert Hartpole of Carlow received an extensive grant from the crown that included not just Blackford Castle but a vast swathe of surrounding territories. His holdings encompassed the manor of Blackford, numerous townlands including Kilteighan, Garrans, and Kilgessin, plus several other castles and lands throughout the lordship of Slemarge. The grant came with specific conditions; Hartpole was to hold these lands in perpetuity for an annual rent of £26, 1 shilling and 2 pence, whilst maintaining six English horsemen, a requirement that underscores the military significance of these frontier territories during the Tudor conquest of Ireland.

Today, the castle’s roughly coursed limestone walls offer little decoration save for a single slit opening in the eastern wall, yet they speak volumes about the contested landscape of 16th century Laois. Once known variously as Rathmadocke or simply “the Blackeforde”, this fortification represents the complex layers of Irish history; built by Gaelic lords for defence, seized and redistributed by English administrators, and now standing as a quiet monument to the centuries of conflict and change that shaped modern Ireland.