The Delhi Sultanate ruled over Northern India from 1206 to 1526 CE. They were known for their exceptional architectural achievements, which can be seen in the many monuments they left behind. Below are the contributions of the Delhi Sultanate rulers to architecture:

1. Indo-Islamic Architecture
The Delhi Sultanate rulers introduced Indo-Islamic architecture, which blended the best of Islamic and Indian styles. This style was characterized by the use of domes, arches, minarets, and intricate geometric patterns. The buildings were constructed using materials such as red sandstone and marble, which were readily available in the region.

2. Mosques
The Delhi Sultanate rulers built many mosques throughout their reign, the most famous of which is the Qutub Minar in Delhi. This mosque is made of red sandstone and marble and is 73 meters tall. The mosque has five storeys, each with a balcony, and is decorated with intricate carvings and calligraphy.

3. Forts
The Delhi Sultanate rulers constructed many forts throughout their reign, which served as their administrative centers and military bases. The most famous of these is the Red Fort in Delhi, which was built by Shah Jahan in the 17th century. The fort is made of red sandstone and is surrounded by a moat. It has many beautiful buildings, including the Diwan-e-Khas, the Diwan-e-Am, and the Rang Mahal.

4. Tombs
The Delhi Sultanate rulers built many tombs to honor their loved ones and themselves. The most famous of these is the Tomb of Humayun in Delhi, which was built by his wife, Haji Begum, in the 16th century. The tomb is made of red sandstone and marble and is surrounded by beautiful gardens. It has many beautiful buildings, including the main tomb and several smaller tombs.

In conclusion, the Delhi Sultanate rulers made significant contributions to architecture, particularly in the areas of Indo-Islamic architecture, mosques, forts, and tombs. Their architectural achievements continue to be admired and studied today.

The Delhi Sultanate's greatest contribution to Indian fine arts was the introduction of Islamic architectural features, including true domes and arches , and the integration of Indian and Islamic styles of architecture
Hindu architecture was also influenced by the Imperial style. The Hindus had already a well-developed style of their own prior to the coming of the Muslims in India. Therefore, features of their past style continued to be the governing factors of their style of architecture.

However, the distinction between these three styles of architecture is only for the sake of convenience of understanding. Otherwise, the period witnessed the growth of that style of architecture which, as a whole, can be called the Indo-Islamic architecture or the Indian architecture influenced by the Islamic art of architecture. This style of architecture was neither purely Islamic nor purely Hindu.

It was, rather, influenced by both the styles and therefore, fairly deserves to be called the Indian architecture of the period of the Sultanate. Iran and India had come into contact with each other much earlier and had influenced the architecture of each other. The Iranians, whatever they learnt from the Indian style, matured it and gave it a perfect Iranian style.

NOTE:- Try to make the above info in order as it is not in proper order.
Hope it helps