Just next to the entrance of City Palace is Jantar Mantar in Jaipur.The largest Stone Astronomical Observatory in the World. And this feature makes it, a special destination for a traveler. Jantar Mantar of Jaipur is one of the five astronomical observatories built by Maharaja Jai Singh, the founder of Jaipur. During the period between 1727 and 1733, Jantar Mantar took its form and structure. Initially Jantar Mantar was named as Yantra Mantra, which means instruments and formulae, but due to mispronunciation of the term, it is changed to the recognized name. Jantar Mantar has a remarkable collection of architectural astronomical instruments. Above all, this observatory still, provides accurate information, which can be compared with today's modern instruments undeniably. The compound instruments, whose settings and shapes are scientifically designed depicts the forte of Medieval Indian Astronomy. Jantar Mantar is wholly constructed with stone and marble. The observatory has fourteen statistical instruments for measuring time, predicting eclipses and to ascertain other astronomical events. Jantar Mantar was carefully renovated in 1901 and was declared a national monument in 1948. Today, Jantar Mantar has become a major tourist attraction in Jaipur.