The Jantar Mantar was conceived as a quest for discovering the mysteries of the Cosmos. The Jantar Mantar is a corruption of the Sanskrit word yantra mantra meaning instruments and formulae. It was built not only to verify astronomical observations made at Jaipur, but also to stimulate interest in astronomy, which had become enmeshed in theory, superstition and religious jargon. Following the style of an observatory at Samarkand, huge masonry instruments were built, keeping in mind the rules of astronomy, the position of the equator, latitudes and longitudes. The observatory at Jaipur has the samrat yantra, the jaiprakash yantra, ram yantra and the 'composite instrument' includes a sundial and a massive hemisphere on the northern wall.
India, in the early decades of the 18th century was a land to turmoil, the Mughal empire was collapsing, its chiefs were busy in internal quarrels, and the Marathas, Portuguese, British, French and Dutch were fighting for the over lordship of India's trade and political fortunes. In this age arose a brilliant star on India's political and intellectual horizon - Maharaja Sawai Jai Singh II, Rajput ruler of Amber, founder of Jaipur, a great builder and ruler and an exceptional astronomer.
Commissioned by Emperor Muhammad Shah, to correct the existing astronomical tables and fix planetary positions anew, Sawai Jai Singh-II, accomplished the task in seven years and for this task, built the first stone observatory in Delhi in 1724 and in Jaipur in 1728. Not only did the masonry instruments suit his purposes, they also satisfied his architectural instincts. Apart from being a permanent memorial to his genius, is secured for him a place along with such distinguished observatory builders like Prince Ulugh Beg, Tycho Brahe and John Flam steed.