Located on the city’s east, with a single entrance and low arch, this door, connects the city to the water, meaning Tigris. In the tablet with the date 1240-1242 on Hanefiis section of the Great Mosque, it is mentioned as “Water Door”. This door, with low arch and single entrance provides passing to Tigris from the city. The entrance to the door from outside is provided by a steady ramp. It is fortified with a two floored rectangular dungeon exactly on the north of the door. Despite the reparations, it had kept its qualities of a Byzantine monument.