The site at Ballymageraghty, formerly territory of the Mageraghty chieftains, came into Malby’s possession through a Crown lease in 1577, followed by a formal grant two years later. By 1584, the property had developed into a substantial stone fortress complete with a watermill, though by then it was occupied by a tenant named Thomas Ruttledge rather than Malby himself.

The surviving architecture tells a story of ambitious defensive design. Two hexagonal towers, each measuring approximately 12 metres across internally, once projected eastward from a main house that has since vanished. These towers stood roughly 30 metres apart, and what remains today are sections of wall rising four storeys high, each floor featuring its own fireplace; a luxury that speaks to the residence’s intended comfort despite its military purpose. The positioning was strategic, taking advantage of a natural rise where the River Suck makes a sharp southward turn.

The castle’s history took another turn in 1616 when Sir Charles Coote acquired the lands and, rather than restore Malby’s fortress, chose to construct a second fortified house immediately to the west. This decision left the original castle to gradually decay, transforming from a symbol of English authority in Connaught to the evocative ruins that mark the landscape today, their hexagonal towers standing as monuments to the turbulent politics of Elizabethan Ireland.