Jantar Mantar is very popular among tourists and the people of Delhi. The structure is another great masterpiece of Indian architecture which shows the scientific acumen of ancient India. Jantar Manter is situated at Parliament Street, very close to Connaught Place. Jantar Mantar is also called Delhi Observatory. It is maintained by the Jaipur government because it was built by Maharaja Sawai Jai Singh II of Jaipur in 1710 A.D. It is a remarkable structure which consists of fourteen geometric devices used for measuring time, forecasting weather changes, predicting behaviour of planets and finding extraterrestrial altitude. All these devices are fixed structures and point to a specific direction. The largest device or instrument is the Samrat Jantar which is 90 feet high and its shadow is plotted in such a manner so that is shows the exact time of the day. Any weather change or the onset of monsoons can be ascertained by the Hindu Chhatri, which is a small domed structure. The whole structure is made of stone and marble with each of then having an engraved astronomical scale. Jantar Mantar finally got the status of a national monument in 1948. It has always attracted architects, historians and scientists from all over the world. Maharaja Jai Singh was a fanatical astronomer himself who studied various works from Hindu, Muslim and European astronomy. He had the perception that the tables used by the pundits were deceptive and the actual planetary changes and predictions of eclipses would not have been possible through these measuring parameters. So he thought that he would find an improved and efficient means through which exact prediction could be made. It was his own inspiration and foresightedness that gave shape to such an instrument. He built other observatories at Jaipur, Ujjain, Benares and Mathura to have an exact calculation. It took almost seven years before the whole structure was fully operational because he wanted to be fully satisfied with the accuracy of the instruments at Jantar Mantar.