A unique structure raised in 1724, now lies in the heart of Delhi's commercial centre near Connaught place. This is the Jantar Mantar, one of several astronomical observatories raised by Maharaja Jai Singh II of Jaipur.
Delhi's Jantar Mantar is the first of the five observatories that he built with large masonary instruments. The various abstract structures within the Jantar Mantar are, in fact, instruments that were used for keeping track of celestial bodies. Yet, Jantar Mantar is not only a timekeeper of celestial bodies, it also tells a lot about the technological achievements under the Rajput kings and their attempt to resolve the mysteries regarding astronomy.

All of these were built as far back as AD 1724-1730 during the period generally known as the dark age of Indian history, when the last great Mughal emperor Aurangzeb had died and the Mughal Empire was rapidly declining.

Jai Singh's idea was to create a rebirth of practical astronomy among the Indian masses and practicing astronomers. However, the lofty ideals of the Jantar Mantar remained unfulfilled as the country at that time was in chaos and the full potential of this observatory was never realized. In the beginning, Jai Singh tried to use brass instruments in this observatory, but soon gave them up because of several inherent flaws. They were too small, for one thing, their axes were unstable so the center often got displaced. He then decided to follow the style adopted by the renowned Arab astronomer, Prince Ulugh Beg, builder of the famous 15th century observatory at Samarkand, Uzbekistan. The massive masonry instruments at Samarkand suited Jai Singh's architectural tastes and promised to be more accurate because of sheer size. In 1730, Jai Singh sent a mission to the king of Lisbon. On its return to Jaipur, the mission brought back a telescope and the court astronomer by the name of Xavier de Silva. The Observatory This unique observatory was completed in 1724 and remained operational only for seven years.