The Jantar Mantar is one of the prominent landmarks in Varanasi. It symbolizes India’s supremacy in astronomy. It is situated at a distance of six kilometres from the Varanasi railway station and is closer to the famous Dashashwamedh Ghat. It is an observatory built by the Maharaja of Jaipur, Jai Singh in 1737. The idea behind the construction of the observatory was to study the movement of sun, moon, planets and other objects of the universe.
The site chosen for the construction of the observatory was the roof-top of the Man Mahal Palace, which is also called as Man Mandir. It is built in the similar fashion of other observatories located in Jaipur, Delhi, and Ujjain. Its construction is a beautiful combination of Mughal and Rajput style of architecture. It has a massive equatorial sundial that records every single movement of the cosmic objects accurately. It is even capable of confirming the onset of eclipses. The instruments designed in various geometrical forms are used to study and record the details of the cosmic objects. There are several instruments in the observatory. Some of the widely used instruments are Samrat Yantra, Prakash Yantra, Laghu Yantra, Chakra Yantra, Digansha Yantra, Dhruva Yantra, Disha Yantra, Ram Yantra, Dakshinobiti Yantra, and Krantivrita Yantra.
Each of the instruments has been assigned to do a specific activity. For example, Digansha Yantra is used to see the horizontal angle of the stars. The Samrat Yantra and Laghu Yantra provide time, sun declination, and angle of the stars. The Chakra Yantra gives an actual declination of stars, and the Dakshinobiti Yantra shows the height of the stars on the meridian.
The Jantar Mantar in Varanasi is a living example of how India has kept with science and technology even 250 years ago. It also shows that our nation had the potential to advance in the field of astronomy in spite of being ruled by kings and queens.