Like many of us, Jai Singh II was fascinated by the stars. His interest led him to build observatories all over his kingdom and the largest, Jantar Mantar, is in Jaipur. Jantar Mantar means "instruments of calculation." These structures, built between 1727-1732, gave Singh II the ability to record time, locate stars, and track eclipses. Jantar Mantar has the largest sundial in the world called Samrat Yantra (The Supreme Instrument). The instruments continue to be accurate and used to this day.