Historical records paint a picture of what was lost: the Down Survey maps from 1656 to 1658 show both a tower and an adjacent gabled structure at this location in Charlestown parish. By 1835, when the Ordnance Survey mapped the area, only a rectangular roofless shell remained, measuring roughly 8 metres east to west and 5 metres north to south. The 1907 survey suggested that portions of the north wall might have still been standing at that time.

Local memory preserved more details about the castle's features before its removal in the early twentieth century. Residents described it as having at least one slit window, typical of defensive architecture, and what they called cellars; likely this refers to a vaulted undercroft rather than true cellars. These architectural elements would have been common in medieval tower houses throughout Ireland, suggesting Cookstown Castle served as a fortified residence for a local family of some standing.

Archaeological investigation has yielded frustratingly little information about the site. Testing carried out in 2000 failed to uncover any artefacts or structural remains that could shed light on the castle's history or its inhabitants. Interestingly, a possible souterrain, one of those mysterious underground passages found throughout Ireland, lies about 20 metres south of where the castle stood. Whether this subterranean feature was connected to the castle or predates it remains unknown, adding another layer of mystery to this vanished piece of Louth's medieval landscape.