We toured a collection of nineteen architectural astronomical instruments built by the Kachwaha Rajput king Sawai Jai Singh in 1734. A Unesco World Heritage site, Jantar Mantar features the world’s largest stone sundial. This photo shows the observation deck of the vrihat samrat yantra (the world’s largest sundial)
With the instruments you can observe astronomical positions with the naked eye. The observatory demonstrates Ptolemaic positional astronomy which was shared by many civilizations.