This Jantar Mantar is just at walking distance from City Palace, Jaipur. I have seen Delhi Jantar Mantar and Ujjain Jantar Mantar and out of all this I think Jaipur is bigger and some of the instruments which are in Ujjain are not there in Delhi.
Since in Jaipur I had only one full one day I preferred to visit the below points in Jaipur by RTDC one day package tour bus.
Brihad Samrat Yantra- Tallest sun dial in world. Measures local time up to accuracy of 2 seconds.
These astronomical instruments are pride of India. These show that knowledge of India in field of astronomy was an example to the world. This place was also a film location in 2006 film “The Fall” as told by our guide..
About 280 years old. Built by Maharaja Jai Singh -II. Jaipur is such place which is visited by on an average 5000 tourists EVERY DAY. To me honestly felt like AMER Fort is like an HIVE and tourists are like Bees. Who so ever visits Jaipur comes to Jantar Mantar as well without fail.