This rectangular limestone tower house, measuring roughly 7.65 metres north to south and 8.5 metres east to west, rises three storeys with an attic and crenellated wall-walk crowning its summit. The tower’s 2.1-metre-thick walls, constructed from roughly coursed limestone rubble with a distinctive base batter, speak to its dual purpose as both residence and fortress.

The castle’s defensive features reveal the paranoia and practicality of its builders. Entry is gained through a two-centred pointed doorway with finely dressed jambs, complete with a yett hole for securing a heavy iron gate. Just inside, a murder hole looms overhead, allowing defenders to rain down unpleasantries on unwelcome visitors. The ground floor chamber, lit by three single windows set deep within wide embrasures, connects to a mural staircase tucked into the northeast corner. This cleverly concealed stairway winds westward through the thick walls, providing access to all floors whilst maximising defensive potential. The upper levels boast more comfortable amenities, including a garderobe chamber at first floor level and a fireplace on the second floor, its tall rectangular chimney stack rising prominently above the wall-walk.

What makes Ballinlough particularly fascinating is its complete defensive system. The tower sits within a roughly circular bawn wall, approximately 33 metres in diameter, punctuated with musket loops that are best preserved along the southern section. Beyond this protective wall lies a deep, wide moat, now visible only on the southern side but originally encircling the entire complex. Two bartizans, or small turrets, project from the northeast and southwest corners, carried on external corbels and accessible from the third floor, providing defenders with commanding views and firing positions. The castle appears on the Down Survey map of 1655, testament to its importance during one of Ireland’s most turbulent periods, when such fortified residences served as crucial strongholds for local lords navigating the dangerous waters of conquest and rebellion.