Qutub-ud-din Aibak laid the foundation for Qutub Minar in 1199 AD and his successor and son-in-law Shamsu'd-Din- Iitutmish completed the structure by adding three more stories. Standing at 72.5 meters, it is the highest stone tower in India. Its base diameter is 14.3 meters and its top diameter is 2.7 meters. It has 379 steps leading to its top story. The lower three stories are made using red sand stone and the top two with marble and sand stone.