1. A mixture of Indian (Hindu) and Iranian (Muslim) Style:
The Sultans of Delhi wanted to construct their buildings on the pattern of Iran and Central Asia.
However, their buildings could not be exact copies of these buildings. They had to employ Indian craftsmen who had their own ideas about the form and method of construction.
Thus though the buildings were designed by Muslim architects to suit the requirements of their religious ideas, yet they were constructed by Hindu craftsmen who formed the finest artistry of the world. Obviously the buildings had a combination of Indo- Islamic architecture.
2. Buildings constructed with the material of Hindu temples:
Several buildings were constructed out of the material used in the temples that were destroyed by some of the Muslim rulers. Quwat-ul-Islam Mosque in Delhi is said to have been built by Qutub-ud-Din Aibak by demolishing a Hindu temple. Likewise ‘Adai-din-ka Jhopra’ a mosque in Ajmer, built in 2 ½ days came into being on the ruins of a Hindu building.
3. Pointed arched in the Muslim structures:
It is noted that the Hindus used square pillars which supported their temple roofs. On the other hand the Muslims used the arches. Besides arches, they also used domes over their buildings and minarets on sides. The use of arch and dome added charm to the Muslim buildings and also enabled them to dispense with the need of a large number of pillars to support the roof.
The Hindus carved the figures of gods and goddesses on all sides of pillars, walls and ceilings also. They also carved various ornamental things like garlands, flowers and temple bells etc. The Muslims did not allow any representation of living things on their buildings. The Hindu workmen who were skilled in decorating the pillars and walls were allowed the use of flowers and trees in the decoration of Muslim buildings.
5. Use of geometrical designs:
During the Sultanate period, geometrical designs began to be used for decoration purposes.
6. Quaranic ‘Ayats’:
The use of Quaranic ‘Ayats’ in the buildings served two purposes i.e. religious as well as decorative.
7. Use of stones and lime:
During the Sultanate period several types of coloured stones like red, light black, yellow and white marbles were used. A very good quality of stone was used to make the buildings strong.
Buildings of the Slave Period:
Qutub-ud-Din Aibak got built the ‘Quwat-ul-Islam Mosque’ at Delhi, probably on the ruins of a Hindu temple as even today one can notice the arches and pillar carvings of the Hindu design. It is said that he also started the construction of the Qutab Minar at Delhi which was completed by Iltutmish.
However some historians do not accept this view and hold the view that it was built by a Hindu ruler. Still others believe that it was built by Iltutmish in the memory of a popular sufi saint Qutab-ud-Din Bakhtiar Kaki.
The tower or the ‘minar’ was originally 71.4 mts high. The circumference at the base is 15 mts and at the top just 3 mts. There were 5 storeys in all. At the end of each storey, there is an enclosed space for the visitors to go round it. It is constructed of red stone only. Qutab-ud- Din also built the Adai-din-ka Jhopra at Ajmer.
Iltutmish got constructed the tomb of his eldest son Nasir-ud-Din Mahmud at Sultan Garhi (Delhi). This was the first tomb built in India by the Turks. Iltutmish also got built the Dargah of Muin-ud-Din Chisti. Balban’s tomb in Delhi is in pure Islamic style.