Firozabad

Firoz Shah Tughlaq abandoned the dry southern ridge and put his city on the Yamuna, where it ran from the riverbank westward toward the ridge — a large, low, well-watered capital rather than a fortress. He was a compulsive builder and, unusually for his century, a restorer: he repaired the Qutub Minar, desilted Alauddin's tank and built a college beside it, and dug canals to bring water in from the north.

He also carried two Ashokan pillars to Delhi from Haryana and Ambala, one of which he raised on a stepped pyramid in his citadel, sixteen centuries after it was carved. The citadel is the Kotla, and it is most of what survives; Timur's army sacked the city in 1398, and later sultans and emperors took its stone for their own walls.