Whilst the tower house itself stands as a testament to medieval defensive architecture, this secondary structure suggests the location once supported a more complex settlement. Archaeological surveys conducted by Lacy in 1983 first documented these remains, noting their probable association with the main castle structure.

The ruins, though now reduced to little more than scattered stones, likely represent an ancillary building that would have served the tower house during its active period. Such structures were common additions to Irish tower houses, potentially functioning as stables, storage facilities, or accommodation for servants and guards. The proximity to the main defensive structure; just eleven metres away; indicates this wasn’t a random pile of stones but rather an integral part of the castle complex’s original layout.

Tower houses like Carricknabraghy were typically built by Gaelic Irish and Old English families between the 15th and 17th centuries, serving as both fortified residences and symbols of local power. The presence of additional structures around these towers speaks to their role as centres of economic and social activity, not merely military strongholds. Though time and weather have reduced this particular building to rubble, its remnants continue to tell the story of how these medieval communities lived, worked, and defended themselves in the often turbulent landscape of 16th-century Donegal.