The name ‘Jantar Mantar’ is derived from Sanskrit word ‘Yantra Mantra’ which means instruments and formulae. Later due to mispronunciation it was changed to the known name.
Jantar Mantar in Jaipur is the most famous one among the five observatories built by Sawai Jai Singh and is located close to the gate of the famous City Palace of Jaipur. Maharaja Sawai Jai Singh II, the Rajput ruler of Amber and the founder of Jaipur was a learned man and an astronomer who was deeply interested in the working of the celestial bodies and so he built the observatory known as Jantar Mantar. Jantar Mantar is the biggest stone observatory in the world, which is still in a running condition.