Jantar Mantar is a famous monument in Ujjain. It was built to find things. In 18th century, Maharaja Jai Singh II came to light and constructed the famous Jantar Mantar to guide the people on the right path of religious science. Jantar Mantar was used for making measurements like sun's revolution, planets direction, lunar mansions etc.
There are various instruments like Samrat Yantra, Jai Prakash, Ram Yantra and Niyati Chakra in Jantar Mantar. The astronomical date were measured and evaluated here using these instruments. The results helped in predicting the movement of sun, moon and planets. Many other facts were learnt from the observation done here.
There are 5 Jantar Mantar monuments in India and the one in Ujjain is the oldest. It is a perfect example of great architecture of 18th century. It still helps in astronomical science and is a tourist place as well.