Jantar Mantar Observatory is located in India, in the center of Jaipur, next to the Royal Palace. Jantar Mantar in Jaipur is the largest and most famous of the five observatories built by Maharaja Jai Singh II. From an early age, Jai Singh was fond of astronomy, firmly believed in astrological forecasts, with the help of which he tried to predict his fate, the outcome of military campaigns and to resist political and palace intrigues. Maharaja even wrote a scientific treatise on astronomy, he conducted active correspondence with scientists and astrologers from around the world. In Jaipur, the solar observatory was built in 1734, it contains 16 of the most modern instruments at that time, with which you could predict eclipses, measure time, track the location of stars and determine the orbit of the Earth's movement around the Sun. In the center of the observatory are the giant sundials of Samrat Yantra, which measure local time with an accuracy of 2 seconds. Their height is 27 meters, and they are the world's largest astronomical sundial. Yantra Raj is one of the largest astrolabes in the world, which allows you to determine the position of stars and planets. Jai Prakash Yantra consists of two hemispherical bowls, drawn by patterns of constellations. Hemispheres "work" in turn - one in the morning, the second - in the afternoon. Each bowl consists of six curved marble slabs with a ring hanging in the center, the shadow of which allows you to determine the location of the Sun. Using other instruments, you can calculate local time in various parts of the world, create a Hindu calendar, measure altitude, azimuth, coordinates of celestial bodies and all 12 constellations of the solar system. All instruments are built of local stone, marble and bronze, their huge size is explained by the desire of Sawai Jai Singh II to get the most accurate calculations. The observatory was constantly used until 1800, throughout the 19th century it was unclaimed, in 1902, during British rule, and in 2006 restoration work was carried out. In 1968, the Jantar Mantar Observatory in Jaipur was declared a monument of National importance, and in 2010 it was inscribed on the UNESCO World Heritage List.