Stretching across 6.5 km, Tughlaqabad Fort lies on Mehrauli-Badarpur Road in capital, Delhi. Built by Ghayas-ud-din Tughlaq, the founder of Tughlaq dynasty that ruled India in 14th century, the fort lies in ruins these days. Believed to have been part of the fifth historic city, the fort consists of massive stone fortifications that sorround the irregular grounds. 15-metre tall city walls, topped by battlemented parapets and strengthened by circular bastions of up to two stories high. The fort also contains remnants of seven rainwater tanks – highlighting the significance of rainwater harvesting even centuries ago.