Delhi Sultanate architecture

Quwat ul-Islam, Delhi, 1196 AD
Beginning about 1100 AD, invaders from the Abbasid Empire conquered most of northern India. These invaders were Muslims, and they needed mosques to pray in. So they got Indian builders to build them a lot of new mosques - big ones, to show how powerful and rich the new conquerors were. They built the earliest mosque in Delhi, the Quwat ul-Islam, out of stones from Hindu temples that the invaders tore down. Like West Asian mosques, this one has a large courtyard surrounded by a covered walkway with columns.

A re-used Hindu column
from Quwat ul-Islam
One side of the mosque has a prayer hall, also full of columns. Just as the Cordoba and Kairouan mosques re-used Roman columns, this one re-used Hindu columns.

Tuglaqabad fort, 1300's AD
The new Muslim rulers of northern India also built themselves castles, like the castles that Islamic rulers were building further west in West Asia. One of these is Tuglaqabad Fort.

Halebid temple, south India (about 1100 AD)
The Muslims didn't conquer southern India, so people kept right on building Hindu temples there. A lot of Indian architects and builders who didn't want to work on Islamic mosques moved to southern India at this time, so that the Hindu temples in the Hoysala kingdom in southern India started to mix northern and southern styles, and also to develop some new ideas. Halebid temple, for example, has five inside rooms instead of just one, and they're arranged in the shape of a star, so the whole temple is star-shaped instead of rectangular. There is just one porch (mandapa) for all of the rooms. The temple has carvings all over showing the lives of the Hoysala kings and stories about Hindu gods.