 A guard room (end 15th century) is installed under this staircase in order to control movement in the underground galleries.On the final level, protected by a strong curtain wall (around 1200 - 15th century) with cannon embrasures (15th century), stands an imposing rectangular keep built in the 12th century.This construction is partly founded on the walls of the residence, or "domicilium", built by the lord of Lavardin, probably in the 1070s.