Jantar Mantar

At first sight, the Jantar Mantar appears like a gallery of modern art. It is, however, an observatory. Sawai Jia Singh II of Jaipur (1699-1743), a keen astronomer and a noble in the Mughal court, was dissatisfied by the errors of brass and metal astronomical instruments.
Under patronage from the emperor, he set on himself the task of correcting the existing astronomical tables and updating the almanac with more reliable instruments. Delhi's Jantar Mantar is the first of the five observatories that he built with large masonary instruments.