It is a large cistern from the Byzantine Period dug into the bedrock in the lower parts of the hill where Silifke Fortress is located. The cistern is 45 m long, 23 m wide and 12 m deep. The cistern is reached through a staircase on one of its corners. Local people pronounce the name of the cistern as “Tekir Ambarı”. The walls of the cistern, which is a rare example found in Anatolia in architectural terms, are supported with smooth face stones, and eight circular arched niches were added on the long edge and 5 circular arched niches were added on the short edge so as to prevent leakage of water and to give it a monumental look.