"Jantar Mantar" , the astronomical observatories was designed by Maharaja Jai Singh II around 1727-1733.King Jai Singh II was very passionate about mathematics and Astronomy. He had studied various works of astronomers when he was in School of astronomy. Jantar Mantar is much bigger astronomical structure, with more complex designs which required lots of measurements. Jantar mantar is constructed with stones and marbels.
It has lots of statistical instrument to measure time and to ascertain other astronomical events. It is the largest astronomical instrument of the world made with stone.
(“Yantra”/Jantar - means Instrument and “Mantra” /Mantar - means Formula).
There are 18 instruments. The name of the few instruments is -
1. Samrat Jantra (It is the largest sundial in the world and can tell time accurately of about 2 seconds)
2. Shasthnasa Jantra
3. The jai Prakash
4. Ram Jantra
5. Mishra Jantra (which measures the shortest and longest day of a year).
Jantar Mantar was renovated in 1901 and was declared the national monument of India later.