The sculpture of Alai Darwaza was commissioned by Ala-ud-Din. The architecture of Alai Darwaza was completely different from its predecessors. In fact this kind of architecture was unknown in India before.

One of the noted features of Alai Darwaza, a gateway, is its system of walling. There are two courses of stretchers that appear alternatively on the walls. While one end of the longer stone laid portion faces outwards, the other penetrates deep into the wall. The walling penetrated into rubble core and this made it stronger. Such method of walling was followed in the later years as well and became a popular feature of Mughal architecture.

The second important feature was the arch. This architectural element is also to be found in the later era in most of the Sultanate tombs. As far as the structure of the Alai Darwaza is concerned it is a rectangular building that is built on a high plinth. Steps have been cut into plinth to reach the interior. The plinth has been carved in bands and the surface of the wall has been divided into two stories. Each story is, in turn, further divided into rectangular panels. There are recessed arches on the lower panels but the upper panels are merely square shaped. Mixtures of sandstone, marble arabesque and decorative carvings have been used to decorate the Alai Darwaza.

The most interesting feature of Alai Darwaza is its central arch. The colossal height of this arch is nearly as much as the monument itself. It is in a rare shape of a horse-shoe. It can also be termed as a keel arch. Inscriptions on white marble have been etched out on its outer rim. On the pother hand the inner rim displays a beautiful sculpture of lotus-bud. The inner facade that faces the mosque and Qutab Minar is completely different. Te sensual and plastic sculptures have been widely used here.

The interior sculpture of Alai Darwaza is as splendid as its outer designs. The huge dome was transferred to its position with the help of a squinch. In that era this was an innovation in the field of the technology. The sculpture of Alai Darwaza thus brings forth both the artistry and the technical aptitude of its contemporary era.