Jantar Mantar

Jantar Mantar is an astronomical observatory in the Old City of Jaipur, Rajasthan, India, beside the City Palace. Sawai Jai Singh II, an astronomer-king of the Kachwaha dynasty, built it between 1728 and 1734 and it is the largest and best preserved of the five observatories he constructed across northern India, the others being at Delhi, Varanasi, Ujjain and Mathura. UNESCO inscribed it as a World Heritage Site in 2010, describing it as an expression of the astronomical skills and cosmological concepts of the court of a scholarly Rajput ruler. The site holds 19 fixed masonry and metal instruments designed to measure time, track the sun, moon and stars and predict eclipses with the naked eye. The Samrat Yantra, a giant sundial around 27 m high, is the most prominent and tells local time to an accuracy of about two seconds. The Jai Prakash Yantra consists of two bowl-shaped hemispheres that map the sky, the Ram Yantra measures altitude and azimuth, and the Rashivalaya Yantra is a set of twelve instruments, one for each zodiac sign. The complex is an open-air architectural and archaeological monument rather than a conventional museum, and visitors walk among the instruments with signboards explaining each, arranged in an informal, loosely thematic sequence of time, position and zodiac instruments. Jai Singh drew on Hindu, Islamic and European astronomical traditions, and the instruments reflect a deliberate effort to improve on the accuracy of metal tools. The observatory fell into disrepair in the 19th century and was restored under Rajasthan government direction, with major repairs in 1901 and later conservation by the state archaeology department. It remains a working site, as the sundial is still used for time reading and local astrologers consult the instruments. The monument is small enough to cover in about an hour, and it gains much from a guide who can explain how readings are taken. Many visitors link it with the City Palace and Hawa Mahal in a single Old City circuit.