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Jantar Mantar, India: Sundials and astronomical instruments keeping time

Written By | Mar 15, 2020

Jantar Mantar is a UNESCO World Heritage site in India with a nearly 300 year old observatory (Courtesy: pixabay}

JAIPUR, INDIA: Recently a lifelong friend came by and delivered a book that could easily be classified as the “World Traveler’s Bible.” Now in its eighth edition, the weighty 960-page volume called simply World Heritage Sites is a detailed journey to all 1073 UNESCO sites around the world, including Janta Mantar.

Arranged in chronological order according to their date of selection, World Heritage Sites are designated by UNESCO which judges them under strict criteria with the aim to reflect the world’s cultural and natural diversity and are of outstanding universal value. Sites that no longer meet these criteria are delisted.

Sundials, Astronomical Instruments, Jantar Mantar, India, Unesco Heritage Site

Yantra Mantra features 19 amazing astronomical and mathematical instruments (Courtesy: pixabay)

Combined with superb photography, several methods of listing such as by country or by cultural criteria such as historic or scenic, etc., detailed maps and complete descriptions of the sites, this book is far and away the best UNESCO reference a globetrotter could possess.

As an example, let’s look at one of the most fascinating sites in the world that you have probably never heard of; Jantar Mantar located in Jaipur, India.

Jantar Mantar, Jaipur, India

The Jantar Mantar is a collection of nineteen architectural astronomical instruments built by the Maratha Rajput king Sawai Jai Singh II, the founder of Jaipur, Rajasthan. Completed in 1734, it features the world’s largest stone sundial, which is accurate to within two seconds.

Sundials, Astronomical Instruments, Jantar Mantar, India, Unesco Heritage Site

The Samrat Yantra the world’s largest sundials, stands 88 feet tall. (Photo: peabod)

The instruments allow the observation of astronomical positions with the naked eye while the observatory is an example of the Ptolemaic positional astronomy which was shared by many civilizations.

The name “jantar” is derived from yantra a Sanskrit word, meaning “instrument, machine.” “Mantar” comes from mantrana, also a Sanskrit word for “consult, calculate.” Therefore, Jantar Mantar literally means “calculating instrument.”

Creating Jantar Mantar

When Jai Singh noticed that the Zij, an Islamic astronomical book that tabulated the parameters used for calculating the positions of the sun, moon, stars, and planets, did not match the positions calculated on the table, he constructed five new observatories in different cities in order to create a more accurate Zij.

Sundials, Astronomical Instruments, Jantar Mantar, India, Unesco Heritage Site

Artist’s rendering of Samrat Yantra in the early 19th century (Courtesy: British Library — public domain)

The astronomical tables Jai Singh created, known as the Zij-i Muhammad Shahi, were continuously used in India for a century though they had little significance outside of the country.

It’s not known when Jai Singh began construction in Jaipur, but several instruments had been built by 1728, and the construction of the instruments in Jaipur continued until 1738.

During 1735, when construction was at its peak, at least twenty-three astronomers were employed in Jaipur. Because of the rapidly changing political climate, Jaipur replaced Delhi as Jai Singh’s main observatory, remaining his primary observatory until his death in 1743.

Sundials, Astronomical Instruments, Jantar Mantar, India, Unesco Heritage Site

Samrat Yantra as it appears today (Photo: peabod)


The history of Jantar Mantar is one of decline and restoration for the next 158 years.

From 1743 to 1750, the observatory lost support under Isvari Singh due to a succession war between him and his brother. Although some restorations were made to the Jantar Mantar by Isvari Singh’s successors, when Pratap Singh took over until 1803, a temple was constructed, and he turned the site of the observatory into a gun factory.

Sundials, Astronomical Instruments, Jantar Mantar, India, Unesco Heritage Site

According to theory, the larger the instrument, the more accuratte it was (Photo peabod)

Ram Singh began the restoration of the Jantar Mantar. Restoration ending in 1876. He even made some of the instruments more durable by inserting lead into the lines in the instruments and restoring some of the plaster instruments with stone.

Unfortunately, the observatory fell into a state of disrepair until 1901 when Madho Singh II began restoration again.

Janta Mantar – measuring time, plotting the stars

The Jantar Mantar observatory consists of nineteen instruments for measuring time, predicting eclipses, tracking location of major stars as the earth orbits around the sun, ascertaining the declinations of planets and determining the celestial altitudes.

Among the instruments on display is Vrihat Samrat Yantra, the world’s largest gnomon sundial which measures time in intervals of 2 seconds using shadows cast from the sunlight.

The Yantra Raj Yantra is a 2.43-metre bronze astrolabe, one of the largest in the world, is used only once a year to calculate the Hindu calendar.

Sundials, Astronomical Instruments, Jantar Mantar, India, Unesco Heritage Site

Yantra Mantra is like being in Disney World for astronomy and mathematics (photo: peabod)

The Vrihat Samrat Yantra, which means the “great king of instruments”, is 88 feet high; its shadow tells the time of day and its face is angled at 27 degrees, the latitude of Jaipur.

The Hindu chhatri (small cupola) on top is used as a platform for announcing eclipses and the arrival of monsoons.

The size of the Jantra Mantra devices is unbelievable

In most cases, the instruments are huge structures, allegedly designed to increase their accuracy. The Samrat Yantra, (Great Sundial), for instance, can be used to tell the time to an accuracy of about two seconds in Jaipur local time.

Sundials, Astronomical Instruments, Jantar Mantar, India, Unesco Heritage Site

The 19 instruments are larger than life (Photo: peabod)

At 88′ in height, the Samrat Yantra is one of the world’s largest sundials

Its shadow moves visibly at 1 mm per second, or roughly a hand’s breadth every minute, which can be a profound experience to watch.

The Jantar Mantar was declared a national monument in 1948 and at long last, finally restored to full capacity in 2006.

Switzerland may have Rolex and London boasts of Big Ben, but for the “time of your life” India’s Jantar Mantar is like no other place on Earth.

About the Author:

Bob Taylor is a veteran writer who has traveled throughout the world. Taylor is an award winning television producer/reporter/anchor before focusing on writing about international events, people and cultures around the globe.

He is the founder of The Magellan Travel Club (

His goal is to visit 100 countries or more during his lifetime.

Read more of Travels with Peabod and Bob Taylor at Communities Digital News

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Bob Taylor

Bob Taylor has been travel writer for more than three decades. Following a career as an award winning sports producer/anchor, Taylor’s media production business produced marketing presentations for Switzerland Tourism, Rail Europe, the Finnish Tourist Board, Japan Railways Group, the Swedish Travel & Tourism Council and the Swiss Travel System among others. He is founder of The Magellan Travel Club ( and his goal is to visit 100 countries or more during his lifetime.