The southern gateway of the Quwwat-ul-Islam mosque was extended by Alauddin Khalji in 1311. The Alai Darwaza is the first through and through Islamic building in character, architecture and ornamentation. Its construction is painstakingly accurate, the decoration are the politically correct geometric designs and is a typical Khali building. It displays a certain Seljuqian influence, like in the huge dome with a central knob, pointed arches shaped like horseshoes, and the 'lotus-bud' fringes of the arches.
The Construction of Darwaza
The Darwaza is built of red sandstone with arched openings on all sides. It is topped off by a wide but shallow dome rising from an octagon-shaped base. The northern arch is semicircular, while the others have the pointed 'true' arch horseshoe shape. The arch frames are embellished with 'lotus-bud' designs, which are also seen in the perforated screens on the sides of the gate. The gateway is very skillfully decorated with complex carvings of the geometric patterns and white marble bands of calligraphy.