The Jantar Mantar (meaning instruments for calculation), Jaipur Rajastan is a collection of architectural astronomical instruments, built by Maharaja Jai Singh II between 1727 and 1734. There are as many as five such facilities in the country including the ones at Delhi and Jaipur. This one at Jaipur is the largest and best maintained of them all. The observatory features fourteen major geometric devices that measure time, predict eclipses, track location of start depending on the earth’s position with respect to the sun, ascertain the declinations of planets, and determine the celestial altitudes. Being a small city, the monuments can be viewed with ease from the Hawa Mahal as well. Seen in the back drop, high on the mountain is the Jaigad Fort.