This trapezoidal stone monument, which now rests against the north face of the tower at the southwest corner of the keep, was relocated here from a nearby graveyard in 1968. The slab likely dates to 1544, though damage has made the exact date difficult to confirm, and bears the partially legible signature of its sculptor, whose name appears to read 'Madoniuf Oravaity'.

The intricate carving on this weathered stone showcases the artistic sophistication of 16th century Irish stonework. At its heart lies an elaborate cross with an interlaced centrepiece from which seven spear-shaped terminals radiate outward. The cross shaft features a double band interlace pattern and rises from a five-stepped Calvary base that contains the sacred monogram I.H.C. The left side of the shaft displays carved figures including a bird and three animals, one possibly a bull, whilst the right side shows three interlace designs, a vine-leaf pattern, and what was once another animal figure, now broken away.

Though time and weather have rendered the inscription largely indecipherable, historians believe this impressive graveslab was created for a member of the McSweeney family of Doe, who held considerable influence in the area during this period. The monument stands as a testament to both the skill of medieval Irish stone carvers and the status of those who commissioned such elaborate memorials, offering modern visitors a tangible connection to the artistic and religious traditions of 16th century Donegal.