Jantar Mantar Observatory is certainly one of the places to visit in Jaipur. It was built by Maharaja Sawai Jai Singh, one of the rulers of Jaipur. Not only did he plan the city of Jaipur perfectly, he also built five astronomical instruments to study space. Jantar Mantar has been declared a World Heritage Site by UNESCO and it has fourteen devices to measure time, track the location of stars, and even predict eclipses. Jantar Mantar is one of the most popular tourist spots in Jaipur.