The real story behind Jantar Mantar.

A Jantar Mantar is an assembly of stone-built astronomical instruments, designed to be used with the naked eye.

A Jantar Mantar is an assembly of stone-built astronomical instruments, designed to be used with the naked eye. There were five Jantar Mantars in India, built between 1724 and 1735. All were built at the command of the Raja Jai Singh II, who had a keen interest in mathematics, architecture and astronomy. A total of five Jantar Mantars were constructed across North India in Jaipur, Delhi, Ujjain, Varanasi, and Mathura. These compilations or Mishra Yantra gather up to 19 different astronomical instruments.