Maharaja Sawai Jai Singh (November 3, 1688-September 21, 1743) was born at Amber, the capital of Kachhawas . He became King of Amber-Juiper, India in 1699 at the age of 11 when his father Maharaja Bishan Singh died. Mughal emperor Aurangzeb bestowed upon him the title of "Sawai" which meant one and a quarter times superior to his contemporaries. This title adorns his descendants even to this date.

Sawai Jai Singh continued his pursuit of knowledge and education even after he was enthroned. He learnt religion, philosophy, art, architecture, astronomy and astrology. He acquainted himself thoroughly with the Hindu, Greek, Muslim and European Schools of astronomy. He studied Ptolemy's Syntaxis, de la Hire's Tabulae Astronomical, Flamsteed's Historia Coelestis Britanica, Newton's Principia, Euclid's Elements and Mirza Ulugh Beg's Astronomical Tables as well as the masterworks of Aryabhatta, Varahmihira, Brahmgupta and Bhaskaracharya.

In 1719 CE, he was witness to a noisy discussion in the court of Mughal emperor Mohammed Shah. The heated debate regarded how to make astronomical calculations to determine an auspicious date when the emperor could start a journey. This discussion made Jai Singh think that the nation needed to be educated on the subject of astronomy. He decided to construct astronomical observatories for this purpose. By 1724, he had completed the first such observatory at Delhi.

All this time Jai Singh was also busy with the ambitious project of shifting his capital from Amber to a city named for him, Jaipur. Construction of the new capital began in 1727 when he layed the foundation stone of Jaipur, and the construction of an observatory began there simultaneously.

In the next few years, Sawai Jai Singh constructed three more observatories at Varanasi, Ujjain and Mathura. These observatories came to be known as Jantar Mantars. The astronomical devices in these observatories are of Hindu origin but the construction technique and masonry is Islamic. Having heard of the observatories in Jaipur, a number of Europeans travelled to visit them in the 18th century.

When he died in 1743, he was cremated at the Royal Crematorium at Gatore in the north of Jaipur.