The Tughlaqabad Fort, Delhi’s third city, was built between 1321-1325 to serve a defensive site with dual purpose. The ud- din-Tughlaq sultan Ghiyas, father of the Tughlaq dynasty. The site, located over a rock it was developed primarily in three parts, i e. a Citadel with fortified wails and bastions (eastern direction of the main entrance from Qutub Badarpur road) and a Palace covering a large rectangular area with high rubble walls is located in the western direction.
Northern direction has been established as the town; the site may be identified as ruins of houses in present condition. The site is considered a landmark of Tughlaq era architectural development. It was developed as a fortified city with high ramparts (heights varying between 9m to 15.2 considering the Mongols onslaught), double-storied bastions, gateways, palaces, mosques & audience halls. The fort was linked to the Tomb of Ghiyasud-din Tughlaq through an Adilabad Fort causeway. The fort was linked to Ghiyasud-din Tughlaq’s Tomb via a causeway to Adilabad Fort.
Ghiyasud-din Tughlaq (A.D. 1321-25) selected this site as his capital after ascending the Throne of Delhi. For strategic Reasons, he built during A. D.1321-23 a massive fort around the capital city, which stands high on scared outcrop of a rocky hill.
Tughlaq fort is basically octagonal on the plane with a perimeter of 6.5 km. It is 10 to 15 m high Rubble-built walls are supported at intervals with bastions and Gates. The rampart walls are perforated with loop-holes and are topped with a line of rugged battlements of solid stone which are also supported with the loopholes currently the fort has thirteen gates and there are three inner gates to the citadel the vast scale, the great strength and the obvious solidity of the whole gigantic in proportion and power-giving to this fort and air of stern and massive grandeur.
Tughlakabad was divided mainly into three portions to the east of this entrance. A rectangular area acted as a citadel, with high walls and bastions. Equally bounded by rubble walls and bastions, a wider area immediately westward housed the places. Beyond this to the north Lay the city. Now marked by Ruins of houses streets in the city. Some of which Ran in a grid pattern from Gates on one side to those on the opposite side is traceable even now. A Tower is known as Bijayi-Mandal and remains of several halls including a long underground passage inside the citadel-enclosure area.
The Fort also included seven tanks, almost ruins of several large buildings. Massive reservoir constructed between Hills to the south of the fourth side. A causeway connects with the Tomb of Ghiyasud-din Tughlaq. While a wide embankment near its south-eastern corner gave access to the Adilabad Fortress built on another hill a little later across from it.