The Jantar Mantar, a popular landmark in Delhi, was the first of the five observatories built in 18th-century India. The largest of them, and the most magnificent though, is located in Jaipur.
Sandwiched between the dazzling gates of the City Palace and the architectural splendour of the Hawa Mahal jharokhas, is the Jantar Mantar of Jaipur. A collection of large-scale astronomical devices made of stone and brass, which could measure time, predict eclipses, map the orbit of stars and calculate distances between planets. This 18th century astronomical marvel was constructed by Maharaja Sawai Jai Singh II (after who, the city is named).

This historically and scientifically relevant site played a vital role in the development of the study of Astronomy in India.
The idea of the Jantar Mantar:
In 1719, there was a heated argument in the court of the Mughal Emperor Muhammad Shah II ‘Rangeela’, over determining an auspicious date for the Emperor to undertake an important journey. All astronomers of the court presented varied calculations and couldn’t seem to agree on a date. At this time, Sawai Jai Singh II was quick to highlight the discrepancies in the Zij (the Islamic astronomical book), and put forth a proposal to bring more accuracy to astronomical calculations.
To this end, he built 5 observatories at sites that had historical, cultural or political significance:
- Delhi was capital of the Mughal Empire
- Ujjain, the capital of Malwa was also on the prime meridian established by the ancient Hindu canons of astronomy
- Varanasi was an ancient centre of learning and Mathura was the legendary city of Krishna
- He also sought to build one in Jaipur – the capital city of his kingdom
The astronomical tables created by Maharaja Sawai Jai Singh II was called Zij-i-Muhammad Shahi: a dedication to the Mughal Emperor.
The term ‘Jantar’ comes from the Sanskrit term ‘Yantra’ which means instrument. Together with ‘Mantra’ (calculate), Jantar Mantar literally means ‘calculating instrument’.
#DidYouKnow: Sawai Jai Singh's chief astronomer was Pandit Jagannatha Samrat who was a major influence in the design of the Jantar Mantar! Click To TweetWith 19 instruments spread out over almost 5 acres, Jantar Mantar should definitely be on your Jaipur itinerary. Here are 5 reasons why:
1) Tell the time using one of the world’s largest sundials!
Samrat Yantras or sundials are not too complex and had been developed hundreds of years before the construction of the observatory. But the one at Jaipur measured time to a precision that had never been achieved before. Standing tall at 27 metres it is one of the world’s largest sundials!
It is capable of measuring time to an accuracy of two seconds. Can you imagine standing here and tracking the passing of time?

The Hindu Chattri at the top of Samrat Yantra was used to announce eclipses or the onset of monsoons.

2) Find your Zodiac-painting at the Rasivalayas Yantra
The 12 instruments of the Rasivalayas Yantra measure the latitude and longitude of a celestial object. Each instrument corresponds to a specific sign of the zodiac. Track your constellation along the Sun’s path and keep an eye out for your zodiac painting!
These miniatures painted inside the arches of the Rasivalayas Yantra can be missed easily because of their small size (just 12” x 15”) but make for perfect postcard-pictures. You’ll find the painting of your zodiac under the arch of the instrument that measures that particular constellation!

3) The geometric patterns make for interesting pictures!
As much as we love the pale yellow walls contrasted against the bright blue Jaipur sky, go old school and take a few monochrome pictures! This will highlight the unusual architecture and the geometric patterns, giving depth to your photos.
Below is the Jai Prakash Yantra : the ‘jewel’ amidst all instruments in the observatory (and also the most complex). The engraved markings on the surface of the Jai Prakash correspond to an inverted view of both the azimuth-altitude (or horizon) and equatorial coordinate systems used to describe the position of celestial objects.

This instrument has two identical bowls, partially sunk into the ground. Within each bowl, you’d find engraved different maps. As you spot the shadow cast on the map, you can figure the sun’s position in relation to the different celestial bodies and planets. Isn’t that fascinating?
4) History + Science : A gun factory, and a research center, the Jantar Mantar at Jaipur has seen it all!
Over the years after Sawai Jai Singh II, the Jantar Mantar observatory at Jaipur underwent significant changes. Some instruments were dismantled to make room for a temple during the reign of Sawai Pratap Singh (1778-1803). The site even hosted a gun factory! Can you imagine – the 400 kg brass astrolabe being used for target practice? Later, under the leadership of Maharaja Ram Singh II though, restorations and repairs were undertaken.

See instruments from across Rajasthan in their Research and Observer rooms!
The Jaipur Jantar Mantar now has a Research Room and an observer Room! You can view 3D models of not just the instruments at the site but also of those brought from other districts of Rajasthan. The 3D model of Jantar Mantar is incredibly detailed. It shows every aspect of the observatory, including the Interpretation Centre and various instruments present in the monument. These rooms are open to both researchers and tourists.

The instruments used in the construction and restoration of the monument are also on display along with a model of the cenotaph of Maharaja Jai Singh II.
If you are particularly creative, use these paper templates to make 3D models of the instruments yourself!
5) The Jaipur Jantar Mantar is a World Heritage site!
The UNESCO World Heritage tag has deemed the Jantar Mantar at Jaipur as the “most significant and best preserved set of fixed monumental instruments built in India in the first half of the 18th century”. The instruments here are also the largest ones in their category.

The observatory also includes some instruments that are not present at the other sites. These include the Kappala Yantra, Rasivalaya Yantras, and Unnatamsha Yantra.
The captivating angles and curves of the instruments at Jantar Mantar appealed greatly to painters too. The traveller-artists visiting India in the 18th and 19th centuries captured their fascination in their paintings.
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Jantar Mantar is more than just an observatory. With its deep insight into astronomy and its centuries-old cultural significance, Jantar Mantar is a relic of both science and history. It offers us a historical perspective to look at science. Even in the 18th c., people like Sawai Jai Singh existed, who had a thirst for the knowledge of the cosmos. His observatory and his quest for astronomical accuracy remind us that the questions regarding the universe that we grapple with today, are but the latest reflection of the age-old curiosity humans have about the secrets of the universe.
Don’t forget to spread the love for cultural heritage!