Largest of the five remarkable observatories made by Jai Singh in five different cities, this is the best-preserved one. It shows the Maharaja passion for astronomy. Translated into 'Instruments of Measuring the Harmony of the Heavens', Jantar Mantar was built between 1728 and 1734. It is a grand celebration of astronomical science. It appears to be a collection of sculptures with each sculpture serving a specific purpose of measuring attitudes, azimuths, calculating eclipses or counting of stars. This is the only observatory out of five built in running condition. Situated within the City Palace Complex, it is cut off from the main buildings.