The foundations measure roughly eleven metres north to south and six and a half metres east to west, and they sit tucked into the south-west corner of a larger earthwork. That context is what makes the site quietly legible: the surrounding earthwork appears to be the remains of a bawn, the walled or embanked enclosure that typically protected an Irish or Anglo-Irish household of some standing, and the building was constructed directly against the bawn's southern and western walls, using them as its own.

The Civil Survey of 1654 to 1656, a systematic land assessment carried out in the aftermath of the Cromwellian conquest, recorded what stood here in 1640. The entry notes 'a Castle & Bawne, a bigg thatcht house' in Garranlea, held by 'Thomas Butler of Carrenlea Esqr. Irish Papist', the last phrase being the survey's standard designation for a Catholic landowner. Whether the foundations that survive represent the thatched house mentioned in that entry, or the remains of an earlier tower house, the compact stone structure of a late medieval defensible residence, is not certain. The two possibilities are not entirely incompatible: a tower house and a substantial thatched dwelling could plausibly have coexisted within the same bawn. A church lies roughly sixty metres to the north-east, suggesting that Garranlea in Butler's time was a small but coherent settlement of some local consequence, not simply an isolated farmstead.