The first observatory called Jantar Mantar (Yantra Mantra or Instrument and Formula) was built by Maharaja Sawai Jai Singh II who was the ruler of Jaipur. Was built some 4 or 5 km from Delhi. Now called Cannouht Place.
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Jantar Mantar Observatory Palace Complex, Jaipur .
In1734, the year of its completion, it was the last outpost of medieval science. The observatory's eighteen fixed observational instruments are sighting devices which measure the position of the sun, stars and planets. Some are built entirely of masonry, others are engraved metal rings and plates set into masonry foundations.