Jantar Mantar of Jaipur is an astronomical observatory built by Sawai Jai Singh between 1724 and 1734. It is included in the ' World Heritage List ' of UNESCO . This observatory has 14 major instruments which are helpful in measuring time, predicting eclipses , knowing the speed and position of a star, knowing the declination of the planets of the solar system , etc. Looking at these instruments shows that the people of India had such a deep knowledge of the complex concepts of mathematics and astronomy that they could give these concepts the form of an 'educational observatory' so that anyone can know and enjoy them.