Situated in the heart of the city of Jaipur, Jantar Mantar is considered as the one of the oldest astronomical observatories in the world. A UNESCO World Heritage Site, Jantar Mantar houses the world's largest stone sundial. There are 16 devices at Jantar Mantar, designated to measure time, observe planetary motion around the sun, and to keep a track of celestial bodies. It is the largest of the five astronomical observatories that Maharaja Sawai Jai Singh II had built. Out of five, three can be seen in Delhi, Varanasi and Ujjain. Jai Singh, who founded Jaipur, had a keen interest in astronomy. And before starting the construction of Jantar Mantar, he sent his scholars to various parts of the world to study in similar observatories. An interpretation centre helps tourists understand the mechanisms of the devices.

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