Jantar Mantar is an observatory, built by Jai Singh, the Maharaja of Jaipur in the year 1737. Jai Singh was a great admirer of science and technology and he was particularly passionate about astronomy. Before the commencement of construction (of observatories) he sent scholars abroad to study the foreign observatories. The emissaries returned with many manuals on astronomy. The Jantar Mantar at Varanasi was built in line with Delhi, Mathura, Ujjain and Jaipur observatories.
The Jantar Mantar was built to measure the local time, the Sun's
declination, altitude, the declination of stars, planets and to
determine eclipses The Jantar Mantar at Varanasi has several masonry
instruments to record the motion, speed and properties starts and
planets and study astronomy that are accurate and can still be used
efficiently today. The Jantar Mantar incorporates multiple structures of
unique form, each with a specialized function for astronomical
These structures with their striking combinations of geometric forms
have captivated the attention of architects, artists, and art
historians. Originally, there were many yantras (instruments). Some of
the important ones are the Krantivritta Yantra, Digansha Yantra, Samrat
Yantra, Prakash Yantra, Ram Yantra, Disha Yantra and Dhruva Yantra.
The Jantar Mantar (astronomical observatory) at Varanasi was built in line with observatories at Delhi, Jaipur, Mathura and Ujjain.