Pragati Maidan, Delhi
A sprawling walled fort built in the 16th century, believed to occupy the site of Indraprastha, the legendary capital of the Pandavas from the Mahabharata. It was fortified in stages by Mughal emperor Humayun and later Sher Shah Suri, whose Sher Mandal library building still stands within the complex. Humayun died here in 1556 after falling down its stairs. The fort's massive Bara Darwaza and Humayun Darwaza gates remain among Delhi's most impressive Mughal-era fortifications.