Ala'i Darwaza (English: Gate of Alauddin) is the southern gateway of the Quwwat-ul-Islam Mosque in Qutb complex, Mehrauli, Delhi, India. Built by Sultan Alauddin Khalji in 1311 and made of red sandstone, it is a square domed gatehouse with arched entrances and houses a single chamber.It was a part of his plan to extend the Quwwat-ul-Islam Mosque on four sides. Although he planned to construct four gates, only the Alai Darwaza could be completed as he died in 1316. It serves as the southern gateway of the mosque. It is located at the southern part of the Qutb complex. It has a special significance in Indo-Islamic architecture as the first Indian monument to be built using Islamic methods of construction and ornamentation and is a World Heritage Site.The Alai Darwaza is made up of a single hall whose interior part measures 34.5 feet (10.5 m) and exterior part measures 56.5 feet (17.2 m). It is 60 feet (18 m) tall and the walls are 11 feet (3.4 m) thick
