The sun sets over the historic observatory of Jantar Mantar in Jaipur, India. The architectural astronomical instruments are built by Maharaja(King) Jai Singh II at his then new capital of Jaipur between 1727 and 1734. He had constructed a total of five such observatories at different locations, including Delhi, while the Jaipur observatory is the largest of all and one of the biggest stone observatories in the world. Jantar Mantar means literally 'calculation instrument'. The instruments are in most cases huge structures. They are built on a large scale so that accuracy of readings can be obtained. The observatory consists of fourteen major geometric devices for measuring time, predicting eclipses, tracking stars in their orbits, ascertaining the declinations of planets, and determining the celestial altitudes and related ephemerides.