During the excavation period 2011-2014, on the eastern side of the Castle near the tower Π4, was discovered the ”Underground Building”. It is a building structured below the ground, and it is visible from one façade only. It has been structured by refined stones medium-sized on the north-south axis, and its dimensions are 5.5×2.5m. Three ramps provide interior access, and a low masonry wall protects the arched entrance. It is considered that the “Underground Building” was used as storage space.