Jantar Mantar

Jantar Mantar in New Delhi is an astronomical observatory made for use with the naked eye, the work of Jai Singh II, Maharaja of Jaipur. A plaque put up in 1910 dates it to 1710, but later research points to 1724. It was the first of five such observatories he raised; the others are in Ujjain, Mathura, Varanasi and Jaipur. Their aim was to compile astronomical tables and predict the movements of the Sun, Moon and planets, and by the time of British rule the Delhi site had fallen into decay.

The complex holds 13 architectural instruments. The Samrat Yantra is an enormous triangular sundial about 70 feet high, its 128-foot hypotenuse aligned with the Earth's axis, with quadrants on either side marked in hours, minutes and seconds. The Jayaprakash, Rama Yantra and Mishra Yantra stand nearby.