In early 18th century Maharaja Jai Singh II of Jaipur constructed five Jantra Mantra in New Delhi, Jaipur, Ujjain, Mathura and Varanasi during the period of 1724-1735. Each was given a distinct name and used for various astronomical calculations. Amongst the Five Jaipur’s Jantar Mantar is largest spread over 18,700 squares meters of area and houses world’s largest sundial.

Jantar Mantar is the observatory of collection of 19 geometric devices measuring time and space for astronomy. It is also used for observing the orbits of Sun. Observatory instruments were built from stone and marble as they are more durable. The instruments allow the visitors to observe the astronomical positions with the naked eye.