What remains today are primarily the footings of the north, west, and east walls, with the south wall being the best preserved of the structure. This tower house, or fortified residence, measures approximately 9.3 metres north to south and 14.4 metres east to west, with walls 1.2 metres thick constructed from roughly coursed limestone rubble. The interior is now filled with collapsed masonry, though careful observation reveals narrow slit windows; one centred in the east wall and two in the south wall, typical defensive features of such buildings.

The castle appears to date from the late 16th or early 17th century, and intriguingly, its dressed stones live on in nearby outhouses built from the castle’s recycled materials. These repurposed cornerstones display punch dressed surfaces with drafted margins, remarkably similar to an inscribed stone dated 1641 now housed in the Blue Ball pub. Local memory preserves tales of a medieval village that once stood southwest of the castle, bulldozed in recent years, and a small building known as the ‘old church’ that was levelled in the 1950s, now marked only by a slight rise in the ground about 100 metres from the castle ruins.

Perhaps the most remarkable discovery associated with the site came in the 1930s when the De Burgo chalice, a 14th century ecclesiastical treasure, was unearthed approximately 180 metres southwest of the castle. This precious artefact now resides in the National Museum of Ireland, serving as a tangible link to the area’s medieval past and suggesting that Aghnananagh held religious as well as defensive significance long before the fortified house was constructed.