While it seems that the witnesses to the Tavera vs.Fonseca lawsuit exaggerated a little bit, «and so thick a wall that in the space by the windowsill would go ten men», the architectural remains reveal a formidable structure of quality masonry with walls 2.30 m thick.
Located at the centre of the fortress, the keep is quadrangular in shape and with 12 m long walls. No remains of the paved ground floor have survived. At the northeast wall there are supporting walls of what could have been the access to the inside of the keep, whose entry was not at ground level but at some height: a very typical feature of the castles of the time. At the southeast, there survived a bench with three stone terraces, a structure that gave the building a more monumental appearance.
A keep razed to its foundations, nowadays it can only be identified by its marks on the rock, and some bonding stones at the bottom of the missing walls. The data available only indicate its exact location and dimensions, but they provide us with no information on its features. The archaeological excavation has revealed how the Irmandiños brought down the keep from its base, at ground level. Some ash remnants at one corner bear testimony to the method used by them and the stonemasons to bring about the collapse of the walls.
Little do we known about its four floors except for some isolated remnants like roof tiles, nails from beams or ornamental elements like capitals or fragments of archivolts. To imagine what it would have looked like, we have the keeps of the castles of Monforte de Lemos, A Nogueirosa (Pontedeume) or Pambre (Palas de Rei).