In clock wise direction: a. A long underground passage of Tughlaqabad Fort located in New Delhi still exists amongst its ruined structures b. One of the most remarkable features of Tughlaqabad Fort are the stone-built huge curved bastions which clearly depict the architectural expertise of Ghiyas-ud-din’s workers c. People spending time at the ruined bastions of Tughlaqabad Fort located in New Delhi d. Mostly in ruins now, Tughlaqabad Fort was built in 1321 by Ghiyas-ud-din Tughlaq, the founder of Tughlaq dynasty.