An archaic architecture
Situated on the north-east corner of the inner ward, the keep is a rectangular tower of about twenty metres high, with walls about two metres thick. Four floors, three of which were vaulted, were accessed by a granite spiral staircase. In the 16th century, Rolland de Gourfaleur had openings created on the west and south flanks. The openings led to a balcony supported by a pair of large double corbels, still visible on the two sides.