By the time of the Civil Survey in 1654-6, this once-imposing structure was already recorded as 'the stump of a Castle…out of repaire', with Theobald Purcell listed as its proprietor in 1640. The building's deterioration continued through the centuries, and when the Ordnance Survey visited in the 19th century, they found ruins of what had been a substantial fortification built from lime and sand mortar, with walls four feet thick.

At that time, despite being largely demolished, sections of the castle walls still stood to a height of ten feet, with the ground floor entrance marked by an arch near the northeast corner of the north wall. The surveyors noted these architectural details carefully, preserving a record of what remained of this medieval stronghold. However, time has been less kind to Fertiana Castle than to many of Ireland's other historic ruins; local sources now report that the castle has completely vanished, leaving no visible trace above ground.

Interestingly, local tradition suggests there may have been a church associated with the castle site, though this remains unverified. Recent attempts to examine the location have proved challenging, with one survey thwarted by the presence of a particularly territorial bull guarding the field. The site's archaeological record comes primarily from historical surveys and local memory, compiled most recently in 'The Archaeological Inventory of County Tipperary' by Jean Farrelly and Caimin O'Brien, ensuring that even though the physical structure has disappeared, its place in Tipperary's medieval landscape remains documented.