The surviving structure offers a glimpse into medieval castle architecture, with its north wall stretching 2.9 metres, an eastern wall extending 4.4 metres, and a western wall measuring 3.2 metres. The western wall features a curious short return at its broken end on the first-floor level, suggesting the original castle’s more complex layout.

The tower’s architectural details tell the story of its practical purpose; at ground level, a blocked arched opening pierces the north wall, whilst the first floor reveals a blocked lintelled opening at the eastern end and the splayed ingoing of a window at the southern end of the east wall. Most intriguingly, broken stonework on the internal faces of both the east and west walls indicates the presence of a sloping garderobe shaft, which likely emptied through the arched opening at the tower’s base; a medieval solution to castle sanitation that would have carried waste away from the living quarters above.

Historical records for Garraunigerinagh Castle remain frustratingly sparse, with the site notably absent from the Down Survey barony maps of 1655-6. What documentation exists suggests it was probably built by the Condon family, before passing into other hands; a land grant from 1588 to Arthur Hyde specifically mentions “the castle and lands of Granagenaghe,” indicating the site’s importance in the late Tudor period. Today, this lonely tower serves as a tangible reminder of the numerous fortified houses that once dotted the Irish countryside, most now lost to time and the elements.