The Qutub Minar in Delhi is India's highest single tower. The 72.5 meter high tower is a splendid affair that measures about 14.32 meters in thickness at the base and gradually tapers with height to about a 2.7-meter width at the peak.
The other historic sites of interest that lie within the Qutub Minar Complex in Delhi are the Quwwat-ul-Islam Mosque, Iron Pillar, Alai Darwaza, Alai Minar, Ala-ud-din Madrasa and the tomb of Illtumish.
The Quwwat-ul-Islam Mosque was constructed on the demolished remains of an ancient Hindu temple near the foot of the splendid Qutub Minar that dominates the Delhi skyline. Supposedly the first ever mosque to be built in Delhi, the Quwwat-ul-Islam mosque courtyard has an amazing Iron Pillar that displays an inscription that has been traced back to the Chandragupta Maurya period. Historians believe the pillar may have been brought from someplace in Bihar, India. An intriguing feature about the 1600 hundred-year pillar is that fact that it consists of 98 percent pure iron that shows no signs of rusting. Scientists are still trying to fathom as to how such a pure state of iron could have been obtained as modern technology has still not been able to achieve this remarkable feat.