The architecture during the Delhi Sultanate was utilitarian. Congregational prayers were preferred by the Muslims, hence the construction of mosques became significant. These mosques outlived the age to provide us with valuable information about architectural patterns.
The main features of the monuments of this period were-
Arch and Dome- The earlier beam and lintel was replaced by arches and the Shikhar was replaced by domes.
Use of lime and mortar- Lime and mortar came to be used for cementing. This helped in the construction of arches and domes.
Building material- Stone was abundantly used for masonry work. Buildings were mostly plastered with gypsum.
Decorations- Calligraphy, geometry and foliation were used for decorations. The Quranic sayings or kufi were inscribed on panels, which formed the main artwork. This form came to be known as arabesque. Hindu motifs like a bell, lotus, swastika etc. were also incorporated.
Some dynastic differences were clearly visible in the monuments. The construction of mosques assumed importance as the Turks established themselves. The important ones are the Quwwat-ul-Islam mosque near Qutb Minar and the Adhai din ka Jhopra in Ajmer. These were constructed out of the materials taken from a Jain temple, later a Vishnu temple, and a monastery respectively. The minar adjacent to the Quwwat-ul-Islam came to be known as Qutb Minar. The construction was started by Qutbuddin Aibak and completed by Iltutmish. The minar was a four-storeyed building initially but lightning destroyed the upper storey. Firuz Tughlaq added two more storeys to it. The first three storeys were constructed with grey quartzite faced with red sandstone, the fourth and fifth were constructed with red sandstone faced with marble. The minar is decorated with arabesque and floral patterns.
The Khalji period brought some new innovations like arches, shaped like horseshoes, with complete use of red sandstone and marble for decorations. Alauddin khalji planned to get a minar constructed, which would be twice the height of Qutb minar, but unfortunately, he could not complete it. However, he added an entrance to the Quwwat-ul-Islam mosque, which came to be known as Alai Darwaza in 1311. Siri Fort in Delhi was also built by Alauddin khalji.
The buildings of the Tughlaqs reflect the growing political insecurity, economic austerity and the religious conservatism they lost the youthful splendour and ornamentation of the earlier period. Seemingly massive and solid, in reality, they were poorly built. The Tughlaq buildings are marked by the presence of “batter” or the sloping walls. The rugged simplicity of the Turks re-asserted itself later in the fortress called Tughlaqabad, constructed by Ghiyas-ud-din Tughlaq in A.D. 1321. Tughlaqabad includes Ghiyasudin’s tomb, Bijay Mandal built by Muhammad Tughlaq and a hall of thousand pillars which has only a few ruins left. Of all the Tughlaq rulers, Firuz Saha proved an indefatigable builder and numerous cities, forts, palaces, mosques and tombs are credited to him. Like the preceding Tughlaq building, however, they too were made of poor materials and clearly lacked the elegance of the slave and the khalji monuments.
The shrunken political empire of the Lodis and the Sayyids seriously handicapped them from undertaking any vast and elaborate buildings. Consequently, with few exceptions, their best efforts were confined to the tomb of kings and nobles which nevertheless reflect an attempt to revive the animated style of the Khaljis. The buildings came to be placed on high platforms. The use of a double dome was introduced to impart a definite skyline to the monuments. The garden around the monuments was another significant innovation of the Lodis. The best example of this are the Lodhi Gardens in Delhi. All these features were adopted by the Mughals, manifested in the Mughal architecture.