Tall minarets were the significant and one of the earliest features of Islamic architecture. A double dome is built of two layers. One layer inside which provides ceiling to the interior of the building and the other layer is the outer one which crowns the buildings. The method of making double dome was practised in East Asia for quite some time before it was imported into India. A cenotaph is an empty tomb or a monument erected in honour of a person or group of people whose remains are elsewhere.
Some of the activities which were prevalent during the Delhi Sultanate period are as follows: religious persecution, prohibition of public worship and destruction of temples. These was often vigorously enforced by the early Muslim rulers.