Whilst historical records place a castle at this spot as early as the 14th century, the surviving stonework may tell a different story; these remains could be from a later period altogether. Today, only the northeast corner of what was once a rectangular building rises from the landscape, its walls bearing the scars of centuries.

The most substantial surviving section is the north wall, which towers approximately 11 metres high and contains the remnants of an intramural staircase that once connected the first and second floors. The eastern wall, measuring up to 2.8 metres thick, features a ground floor doorway at its northern end. This entrance leads directly into what was once a barrel-vaulted chamber, now partially collapsed, that stretched more than 7.7 metres east to west and 6 metres north to south. A second doorway in the chamber’s south wall once provided access to another room, though this has long since vanished.

These ruins offer a glimpse into the defensive architecture typical of medieval Ireland, where thick walls and vaulted chambers provided both security and storage for local lords. The castle’s position near Lough Mask would have been strategic, allowing control over water routes whilst providing natural defence on one side. Though time has claimed much of the structure, what remains at Ballindeonagh continues to intrigue archaeologists and visitors alike, its stones holding secrets that historical documents alone cannot fully reveal.