Q. Sher Mandal, an octagonal building inside the Purana Qila complex served as the library of which of the following?
Answer: Humayun
Notes: Sher Mandal, an octagonal building in Purana Qila, was built by Sher Shah Suri as a library for Humayun. It features a blend of Timurid and indigenous architecture. Humayun used it as an observatory and died from a fall there in 1556. Originally named Dinpanah, Purana Qila was intended by Humayun as the "Refuge of the Faithful" before being captured by Sher Shah Suri.