Jantar Mantar
Built for the task of revising the calendar and astronomical tables, Jantar Mantar is one of five sites built by Maharaja Jai Singh II of Jaipur, from 1724 onwards.
Jantar Mantar consists of 13 architectural astronomy instruments.
The primary purpose of the observatory was to compile astronomical tables, and to predict the times and movements of the sun, moon and planets. Some of these purposes nowadays would be classified as astronomy.
The Jantar Mantar comprises of the Samrat Yantra, the Jayaprakash, and the Misra Yantra.
Built for the purpose of astronomy and astrology, Jantar Mantar had decayed considerably by 1867.