The city of Siri was the second city of Delhi built by Ala-ud-din Khilji in 1311 AD. The fort had the Palace of Thousand Pillars, which is now in ruins. Only the embattlements have left of the entire fort. The story goes that Ala-ud-din got the heads of the infidels whom he had got killed dug in the foundation of the fort. The fort thus got its name as the Siri Fort. But there is no supporting evidence to believe this story. Ala-ud-din built a vast water reservoir, Hauz-I-Shamsi in the present Hauz Khas area to have a continuous supply of water in the city.