Explanation:

Jantarmantar, the Jantar Mantar is an astronomical observatory built in 18th century Rajasthan. It is an astronomical observatory which was built by the Rajput King Sawai Jai Singh of Rajasthan in 1738 CE. It is a collection of 19 astronomical instruments including world’s largest stone Sundial. All these instruments are man-made. The observatory consists of instruments which were used to calculate celestial coordinate systems, the horizon-zenith local system, the equatorial system and the ecliptic system. One of India’s best-preserved observatories, this monument is a great example of the scientific as well as the cultural heritage of India.