Jantar Mantar or Vedh Shala is located in the holy city of New Ujjain.

It is an observatory built by Maharaja Jai Singh II in 1725 which consists of 13 architectural astronomy instruments.

Motion, speed and properties of stars and planets were also recorded using several special instruments.

Subsequently between 1724 and 1737, Jai Singh II had five observatories constructed in Jaipur, Mathura, New Delhi, Ujjain and in Varanasi.

[4] Geographically, the city of Ujjain is considered the Greenwich of India because the first meridian of longitude in the Indian tradition passes through it.