Purana Quila the citadel was raised by the Afghan, Sher Shah Suri, who temporarily deposed Humayun. Sher Shah, who made a major contribution to public works, built the Qila Kunha Mosque and the Sher Mandal within the citadel in 1541. The purpose of the latter is not so clear though it is thought that Humayun housed his library there. He fell on i'ts steep stairs while answering the call to prayer, and died as a result three days later.
Delhi's Zoological Park is adjacent to the Purana Qila.