The red sandstone walls of Lal Qila meaning the Red Fort, extend for two km and vary in height from 18 metres on the river side to 33 metres on the city side. Shah Jahan started construction of the massive fort in 1638 and it was completed in 1648. The chief attraction of the Red Fort, is some very beautiful palaces and handsome public buildings, such as the Lahore gate - the main gate of the fort,the Diwan-i-Am (hall for public audiences), Diwan-i-Khas (hall for private audiences), Rang Mahal (water-cooled apartment of royal ladies), and the Pearl Mosque, built of white marble.There is a small museum on the fort's premises and a small shopping arcade.

Just south-east of New Delhi lies the Old Fort or Purana Qila. This is supposed to be the site of Indraprastha, the original city of Delhi. The Afghan ruler, Sher Shah, who briefly interrupted the Mughal Empire by defeating Humayun, completed the fort during his reign from 1538-45, before Humayun regained control of India. The fort has massive walls and three large gateways and a small octagonal red sandstone tower ,the Sher mandal,later used by Humayun as a library from where he fell and later died. Just beyond it is the Qila-i-Kuhram Mosque,or the Mosque of Sher Shah.

Tughlaqabad constitutes the third city of Delhi. The ruined fortress is 8 km east of the Qutub Minar. The tomb of Ghiyas-ud-din Tughlak, founder of the dynasty who built the city, is across the road from the main entrance to the fort which is supposedly under a curse from the Sufi Saint, Azam-ud-din. Tughlaqabad became a ghost city 15 years after its birth. The fort of Adilabad, south of Tughlaqabad , was built by Ghiyas-ud-din's son and successor, Muhammad bin Tughlak.