The Qutub Minar was started in 1199 AD by Qutub-ud-Din Aibak and completed by the sultan's successor and son-in-law, Iltutmish. The building is 72.5 m high and has 379 steps from the bottom to the top. The Minar is tapering with the diameter of the base is 14.3 m while at the top floor it is 2.7 m. The Qutub Minar is still the highest stone tower as well as one of the finest Islamic structures ever raised in India. It is made of red and buff sandstone. Aibak constructed the first floor and the tree more storeys were added by Iltutmish. All the storeys are surrounded by a projected balcony encircling the Minar and supported by stone brackets, which are decorated with honeycomb design, more conspicuously in the first storey. The first storey and its balcony have the curved and fluted design. The second storey has only curved design while the third storey has only fluted design. The Qutub Minar is decorated with floral motif and arabesque.
The inscriptions on the surface of the Minar suggest that Firoz Shah Tughlaq (AD 1351-88) and Sikandar Lodi (AD 1489-1517) repaired it. Firoz Shah renovated the top floor and added marble to the building. Quwwat-ul-Islam Mosque was built by Qutub-ud-Din Aibak in AD 1198. It is the earliest mosque built by the Delhi Sultans. It consists of a rectangular courtyard enclosed by cloisters, erected with the carved columns and architectural members of 27 Hindu and Jain temples. These temples were demolished in order to construct the mosque. The Qutub Minar was probably built as a minar for the purpose of azaan by the muezzin. A lofty arched screen was erected and the mosque was enlarged by Iltutmish and Ala-ud-Din Khalji With in the mosque complex is the Iron Pillar, which dates back to 4th century AD. The pillar bears an inscription, which states that it was erected as a flagstaff in honor of the Hindu god, Vishnu, and in the memory of the Gupta King Chandragupta II (BC375-413). The pillar also highlights ancient India's achievements in metallurgy. The pillar is made of 98 per cent wrought iron and has stood 1,600 years without rusting or decomposing. The Tomb of IItutmish was built in AD 1235. It is a plain square chamber made of red sandstone. It is profusely carved with inscriptions, geometrical and arabesque patterns in Saracenic tradition on the entrances and the whole of interior. It s said that it earlier had a dome, which fell down because the walls could not bear its weight.
Alai Darwaza, the southern gateway of the Quwwat-ul-Islam mosque was constructed by Ala-ud-Din Khalji in AD 1311. The gateway is the example of the use of horseshoe arch and true dome for the first time. This is the first building, which employed Islamic principles of construction and ornamentation. Ala-ud-Din Khalji built a madrasa towards the southwest of Qutub Minar to impart religious education to the children. He also commenced the construction of the Alai Minar with the intention of making it twice the size of earlier minar. It is to the north of Qutub Minar. He could complete only the first storey, which now has an extant height of 25 m. The other remains in the Qutub complex comprise Madrasa, graves, tombs, mosque and architectural members. The Qutub Complex is a fine example of the Indo-Islamic style of architecture.
The artists employed by Aibak and Iltutmish was Hindus and the raw material was also obtained from existing Hindu and Jain temples. The figures carved on the pillars were disfigured by them because it depiction of human and animal figures is not allowed in Islam. By the time Ala-ud-Din Came to power Muslim rule was established in the country and there were many artists who have come from the Central Asia. Thus the difference in the buildings of the period of Qutub-ud-Din Aibak, Iltutmish and Ala-ud-Din Khalji is prominent. The buildings of the Qutub Complex are listed in the UNESCO's World Heritage Sites in India.
