Bash Tabiya, an early Ottoman structure, was built prior to the eleventh century, as a fortress along the Tigris. The ruins are situated on the north side of the shrine of Imam Yahya, near to the thirteenth century palatial remnants of Qara Saray. The fortress sits atop a network of underground passages, with two primary gates; one leading to the west, and the other leading down to the Tigris. Once a key strategic asset, the fortress was eventually demolished under Tamerlane in 1393/795 AH, and existed in ruins until later rebuilt by the Ottomans. Following the end of the British Mandate, the property was taken over by the Department of Water and Electricity, and municipal buildings and a cafe were constructed on the former castle grounds.
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