Having been inhabited right from 300 BC, Purana Qila is where you can sneak a peek into the city's past. It is said to be one of the most ancient sites in Delhi. The stories also go that Indraprastha, the legendary capital of the Pandavas, was located here. What you'll find standing today at Purana Qila itself are three gateways, a stunning mosque, a stepwell, a bath complex and a pleasure resort-turned-library.