Qutubuddin Aibak was the founder of the Delhi Sultanate and the Mamluk dynasty. He initiated the construction of several important buildings. The Kubbat-ul-Islam mosque (Quwwat-ul-Islam) in Delhi and the Adhai din Ka Jhopara mosque in Ajmer were among his constructions. He also started the construction of the Qutub Minar, though it was completed by his successor, Iltutmish. The Alai Darwaza is the southern gateway of the Quwwat-ul- Islam mosque complex. It was constructed much later by Alauddin Khalji, the second ruler of the Khalji dynasty, around 1311 AD.