Jantar Mantar observatory, Jaipur, a collection of architectural astronomical instruments built by the Rajput king Sawai Jai Singh II in 1734 - Bildbanksfoto

The instruments allow the observation of astronomical positions with the naked eye. The observatory consists of 19 instruments for measuring time, predicting eclipses, tracking location of major stars as the earth orbits around the sun, ascertaining the declinations of planets, and determining the celestial altitudes and related ephemerides. The observatory is an example of the Ptolemaic positional astronomy which was shared by many civilizations.