Purana Quila (Old Fort) of Delhi, the national capital city of India, is one of the ancient sites. According to Hindu literature the fort marks the site of Indraprastha, the magnificent capital of the Pandavas. Some of the remains are said to be of 3rd century BC. However, the present construction was carried out by a Afgan ruler Sher Shah Suri between 1538 to 1545. He wrested the throne of Delhi from the Mughal Emperor Humayun. It is said that the Mughal king Humayun fell from a tower here accidentally and died. The structure is now a massive rubble wall and imposing gateway houses. There is a mosque in it that has a double storied octagonal tower.