Excerpt:
Maharaja Sawai Jai Singh II ruled the state of Jaipur in Rajasthan, India from 1699 to 1743. In 1728 he founded the capital city of Jaipur about 200 km southwest of Delhi. As a scholar he read the works of Ptolemy, Euclid and Persian astronomers. Wanting to improve the Indian calendar and the ability to precisely locate the Sun, for purposes of map making, he built five astronomical observatories in India, at Delhi, Jaipur, Varanasi (or Benares), Ujjain and Mathura. The instruments at these observatories, based on Moslem design, perhaps copies of the large 15th century instruments at Samarkand, Uzbekistan built by Ulugh Beg, were large masonry structures equipped with protractors and marked grids to aid in the precise measurements of the location of celestial objects.