It was originally built by Saif ad-Daula al-Hamadani but was completely rebuilt in 1256 by An-Nasir Yusuf who renewed the southwestern part of the city wall between the Qinnasrin and Antakeya gates. The architecture of Bab Qinnasrin was formed by two massive towers of unequal heights. The western tower, eighteen meters high, was used for defense while the eastern one, twenty-six meters high, formed the entrance. The Ayyubid portal in the form of a tall arch leads to a tripartite hall with a cross vaulted middle chamber. The chamber opens into another cross-vaulted chamber that is connected to the western side of the gate by a corridor that extends to the wall behind the western tower. Passing through two more chambers, one enters the city. The plan's sequence of rooms form an enclosed square with an open court in the middle that has a water well, cisterns, and flour and oil mills. The gate also holds the Shrine of Khalīl at-Tayyār. The western side has been completely demolished. The innovative plan establishes this structure as a fortress comparable to the Citadel Gate.