A stunning and historic collection of nineteen architectural astronomical instruments, The Jantar Mantar monument of Jaipur, Rajasthan was built by the Rajput king Sawai Jai Singh, and completed in 1738.
The monument features masonry, stone and brass instruments that were built using astronomy and instrument design principles of ancient Hindu Sanskrit texts, and with data from Islamic astronomy during the Mughal Empire. It is located near City Palace and Hawa Mahal of Jaipur and also features the world’s largest stone sundial, Vrihat Samrat Yantra, and is a UNESCO World Heritage site
The Vrihat Samrat Yantra, which means the “great king of instruments”, is 88 feet (27 m) high. The gnomon’s upper face is angled at 27° (the latitude of Jaipur) and follows the local meridian, pointing to geographical north at its highest point. The shadow cast by the gnomon falls on a pair of marble-faced curving quadrants on the east and west sides of the Samrat Yantra. Unlike on a normal flat sundial, the hours are spaced equally apart because the quadrants are curved.
The sundial can tell the time with an accuracy of about two seconds. The shadow moves visibly at 1 mm per second, or roughly a hand’s breadth (6 cm) every minute. The Hindu chhatri (small cupola) on top is used as a platform for announcing eclipses and the arrival of monsoons.