It exists, at least for now, entirely as a pattern of electrical resistance in the soil, its outline drawn not by excavation but by geophysical survey equipment scanning the earth at depths of between 0.6 and 1.6 metres. Alongside it, a smaller rectangular feature to the east, approximately five metres in each direction, may be a separate building or an annexe attached to the circular structure. Neither has been confirmed by all the survey methods used, which gives them a provisional, almost spectral quality.

The surveys were carried out in 2008 and 2009 by Target Archaeological Geophysics, working on behalf of the Ballintober Community Group with funding from the Heritage Council. The techniques used, resistivity and gradiometry, measure subtle variations in how the ground conducts electricity and responds to magnetic fields, and can reveal buried foundation trenches, pits, and building outlines that have left no visible trace on the surface. Ground penetrating radar, a third method applied to the same area, did not confirm the structures, a discrepancy that is not unusual in complex archaeological deposits and that leaves the question of what exactly lies beneath Ballintober's northern ward genuinely open. The castle itself is a substantial Anglo-Norman enclosure, and the presence of possible internal structures of this kind raises questions about how the space within its walls was actually used and by whom over the centuries of its occupation.