After a dramatic defeat of Prithviraj Chauhan, the rule of the Hindu dynasty over Delhi came to an end in 1191 A.D. It was captured by Qutabuddin Aibak, the slave commander of Mohammad Ghori, after numerous defeats. This was the beginning of Delhi Sultanate and for next 600 years Islamic dymasties prevailed. The seat of the rule of invaders had been Mehrauli, which was the living capital of Hindu predecessors.
After the death of Mohammad Ghori in 1206 Qutabuddin Aibak became the first Sultan of Delhi and Quwwat-ul-Islam was laid on the site of Hindu fort as Delhi's first mosque. The construction of Qutab Minar (now World Heritage monument) was started by Aibak and continued by Iltutmish and his successor. It became the most dominating symbol and a landmark of Delhi. However, legend says that the Rajput King Prithvi Raj raised his minarate for astronomical observations. His daughter could see the holy Yamuna from its top. On the outskirts of Mehrauli a water reservoir known as Shamsi Talab and Jahaz Mahal were built over a faint footprint, said to be that of the Prophet. Jahaz Mahal, built in 1230 A.D is a beautiful structure of grey and red stone. It is the venue of annual festival of Phool Walon Ki Sair. The citadel wall, observation towers, numerous tombs and other lofty structures of Mehrauli dominate its hilly landscape. These reflect that Mehrauli during the Sultanate era was one of the most magnificent and thriving capital city. It had often been referred as Old Delhi till the construction of New Delhi, after which Shahjahanabad was termed as the Old Delhi.
The successor of Iltutmish were weak and unable to control the affairs of the State. Iltutmish illuminated his daughter Razia Sultan as his successor. The elevation of the woman to the status of Sultan was severely resented by the nobles and the aristocracy, and she was put to death in disguise. Her tomb exits at Bulbuli Khana near Turkman gate. However, the capital city was not confined to Mehrauli, but it extended much beyond during her reign. The monuments constructed during this phase of Sultanate rule laid the foundation of Indo-Islamic Architecture in India.