PURANA Q1LA, literally “Old Fort”, stands on an ancient site that has been continuously occupied since 1000 BC, as rchaeological excavations have revealed. The brooding ramparts of the fort now enclose the remains of the sixth City of Delhi, Dinpanah, which was begun by the second Mughal emperor, Hurnayun. His reign, however, was short and in 1540 he was overthrown by the Afghan chieftain Sher Shah Sur . Sher Shah added several new structures and renamed the citadel Shergarh (“Lion’s Fort”). After Sher Shah’s death Humayun regained his throne. Of the many palaces, barracks and other edifices built by these two rulers, only Sher Shah’s mosque and a building that was probably Humayun’s library remain standing today. The Qila-i-Kuhna Mosque, built in 1541, is a superbly proportioned structure with fine decorative inlay work in SA” JAI S1NGH II of Jaipur, a keen astronomer, built this observatory in 1724 because he wanted to calculate planetary positions and alignments accurately, in order to perform sacred rituals and pujas at propitious moments. One of the five observatories he built , Jantar Mantar’s instruments are large and fixed, making them resistant to vibration and therefore exact.
The Saturat Yantra, a right-angled triangle whose hypotenuse is parallel to the earth’s axis, is a gigantic sundial, with two brick quadrants on either side of it to measure the sun’s shadow. The Ram Yantra, reads the altitude of the sun, and the Jai Prakash Yantra (invented by Jai Singh II himself) verifies the time of the spring equinox. Now obsolete, the observatory lies in the centre of a pleasant park surrounded by high-rises. red and white marble and slate. To the south of the mosque is Iumayun’s library, known as Sher Handal. A double-storeyed octagonal tower of red sandstone, it is crowned by an elaborate chhatri (open pavilion) supported by eight pillars. This was the tragic spot where the devout emperor, hurrying to kneel on the steps for the evening prayer, missed his footing and tumbled to his death in January 1556. The ramparts of the Purana Qila have three principal gateways, of which the imposing red sandstone Rara the on Darwara western wall is the main entrance. Humayun’s Tomb can be seen from the southern gate.