India’s Scientific Playgrounds: Mapping the Jantar Mantar Observatories

Why Ujjain is considered the Greenwich of India.

Please login to bookmark

The various instruments at the Jantar Mantars chart celestial movements with great accuracy. Photo: Tibor Bognar/Encyclopedia/Corbis/Imagelibrary

I’d landed in Delhi that very morning, dead tired after an overnight flight from Europe, backpacking for the first time, and suitably clueless about everything. Connaught Place seemed vast, imperial, and too grand to get my head around. Touts chased me in circles, shoe polishers threw greenish snot globs on my sneakers, ear cleaners tried to clean me out. Defeated, I scurried down Sansad Marg where I suddenly saw something that spoke to me. Geometric structures in red sandstone, shapes that had clarity, focus, and oozed science. Big, like an Athenian ruin. I instantly liked it. Jantar Mantar was fenced in, so the touts didn’t follow me beyond the ticket window of the park with the sculptures. Inside, people lay on the lawns in post-lunch stupor.

I had no clue what I was looking at, or how these massive structures had been built, by whom, or why. The best guess that came to my mind was that it was a sci-fi set from the silent movie era, a cluster of dreamlike, cubist edifices, left behind by visionary filmmakers. (Disclosure: I was younger and more pretentious then.)

The structures were more daunting as I got closer, with their strangely curved shapes, sweeping upwards, like skateboard ramps built for a race of giants. Or at least intellectual giants, I thought, once I understood that the complex had something to do with ancient astronomy. One of the structures had the shape of a Roman amphitheatre, and inside it was an intricate measurement system made of stone slats, for calculating something or the other.

Connaught Place Samrat yantra Delhi

The Jantar Mantar near Connaught Place is one of Delhi’s mandatory tourist sights. It has also been a venue for various public demonstrations, like Anna Hazare’s campaign for a strong Jan Lokpal bill. Photo: Silwen Randebrock/Imagebroker/Dinodia

Most stupefying was the samrat yantra, a huge triangular structure that appeared to pierce the sky. Next to it, a stone panel attempted to explain what I was looking at. The samrat yantra, it said, was an instrument consisting of a gnomon (I was lost already), the hypotenuse of which was aligned with the earth’s axis (huh?), while its surrounding quadrants were parallel to the equator (hmm). By the time I reached the end of the explanation I was ready to faint, and only partly because of the heat of Delhi in June.

Whatever it was that I was looking at, it was the high point of my first day in India, and I wandered in a state of hypnosis from one monument to the next for a good part of that afternoon. But it took me until now, 25 years later, to understand what I saw.


Ujjain, in central India, the month of June this year. Each night, I am reminded of the temple city’s sacredness when the phone in my room rings promptly at 1.30 a.m. When I complain at the reception, I am informed that the hotel’s telephone system is programmed to give guests an automatic wake-up call so that they can make it in time it for the 4 a.m. bhasma aarti at the main Mahakaleshwar temple. I point out to the receptionist that I don’t need to wake up so early every day, and he says he’ll have it fixed. But the next morning at 1.30 a.m. sharp the phone disturbs my sleep again. Must be God’s will.

Hours later I’m still yawning as I stroll on the shoulder of a dusty road on the outskirts of Ujjain, whose 2,500-year history makes it as ancient as Rome. It was once the seat of the Emperor Ashoka. In the fifth century, the Guptas ruled here during one of India’s Golden Ages. It has always been a centre of learning and spirituality. Even today Bollywood celebrities and political leaders rely on the astrologers of Ujjain.

I’m searching for one of the city’s most intriguing extant old constructions, the 18th-century Jantar Mantar on the bank of the sacred Shipra River. A series of five astronomical observatories were built in north India 300 years ago by Rajasthani royal and science nerd Sawai Jai Singh II. Though there is some ambiguity about which came first, my research has led me to believe that the Ujjain Jantar Mantar predates the rest. It is the only one that is still in use.

Sundial Ujjain Delhi Jantra Mantra Shanku yantra Nadi-valay yantra

The sundial at Ujjain’s Jantar Mantar clocks time with 20-second accuracy. Most of the instruments depend on sunlight, so to understand how they work make sure you visit on a sunny day. Photo: Dinodia

When I find it, I’m greeted by Baney Singh, gardener-cum-self-appointed guide, who offers to show me the finer points of these colossal pieces of shining white marble. Do they work? If so, what do they do? He proudly explains the intricacies of things with tricky names such as shanku yantra and nadi-valay yantra, and I keep nodding, initially as clueless as that first day in Delhi. But then, at the massive samrat yantra, or sundial, I’m hit by a sense of déjà vu—soon followed by insight, as Mr. Singh points out how the dial’s shadow creeps across the curved graded quadrants. I actually see it recording the time with 20-second accuracy. The thing still works like clockwork.

Another instrument records the varying length of days: From the shortest in December to the longest in June. When the sun hits its noontime zenith in June, the shadow of the instrument magically disappears—again, this happens right in front of me. It’s a tropical phenomenon that has to do with the fact that Ujjain is situated on the Tropic of Cancer.

Panchang booklet vUjjain’s Jantar Mantar Delhi

The Panchang booklet, published annually by Ujjain’s Jantar Mantar observatory, forecasts the timings for celestial moves. Photo: Zac O’Yeah

The resident astronomer, B.K. Tiwari, who turns up for duty a little later, explains to me how the “transit instrument” or bhitti yantra (a high wall with esoteric markings on it), is indispensable for computing the annual panchang or “Astronomical Ephemeris of Geocentric Places of Planets” a booklet published by Ujjain’s Jantar Mantar observatory containing tables forecasting the timings for celestial moves and shakes for the coming year. From his office, one can buy mint copies of the first panchang, published in 1942 at the cover price of ₹10. It’s an antiquarian treasure and a perfect, easy-to-carry souvenir. In it, I read that “for centuries, Ujjain has been enjoying the astronomical importance of being the Greenwich of India.” And that ancient texts locate the position of the zero meridian here, which goes to explain why this particular site was chosen for the first Jantar Mantar.

Because it is the only one of these structures still in practical use, every year, over 8,000 schoolchildren, as well as many astronomy scholars, come to see it. There are plans afoot to acquire an 18-inch telescope and a new digital projector for the 50-seater planetarium, to make this ancient monument a full-fledged modern observatory.

It is believed that the Jantar Mantar in Ujjain is the prototype for the four later ones. All were built by Sawai Jai Singh II, the erstwhile ruler of Amber (Jaipur). Under Mughal rule, he was appointed the governor of Ujjain in the 1710s. An expert on Arabic, Greek, and other astronomical traditions, Jai Singh was aware of large-scale brick and marble instruments built by Timur’s grandson Ulugh Beg in Samarqand circa 1428. He apparently also sent a fact-finding team to Europe to check out the latest technologies there. Jai Singh designed many aspects of these instruments himself.

It is thought that he completed the Ujjain observatory in 1719, when he was about 30 years old. The others followed a decade later. Besides Delhi, he erected Jantar Mantars at Jaipur and two sacred cities: A smaller one in Varanasi and one in Mathura that unfortunately had disappeared by the 1850s.

While the one I visited in Ujjain may be the oldest, the Jaipur observatory is definitely the grandest. Getting into Jaipur’s old Pink City, I find it easily enough, in a complex adjacent to the City Palace.

Fleeing the touts in Johari Bazaar outside, I stop to breathe and look around. There is a samrat yantra sundial here too, only this one is a massive 62 feet high. Construction began in 1728 and took seven years, at the same time when Jai Singh was building his scientifically planned capital city—named Jaipur after himself, but of course.

Was this, at the time the biggest observatory of its kind in the entire world, a way to show off, I wonder as I walk around the compound of about 20 seriously big instruments. The observatory, recently proclaimed a UNESCO World Heritage Site, is certainly something this city can still be proud of.

Samrat yantra sundial Delhi Sawai Jai Singh II

Sawai Jai Singh II built the grandest of the five Jantar Mantars in Jaipur at the same time as he built the city in the early 1700s. No cost was spared in the construction of this astronomical observatory. Photo: TPG/Top Photo Group/Dinodia

In this age of digital watches and out-there software, these instruments may appear clumsy and bulky. But if one considers that they were built centuries before computer-aided design (indeed, the Jantar Mantars are now being researched with the help of 3D software), they are amazingly precise.

The nearly 300-year-old sundial here is aimed exactly at the North Star, I realise, walking up to it with new appreciation for Jai Singh’s genius. With this larger-than-life astronomical laboratory, he attempted to map the positions and trajectories of planets, and gather knowledge about space in a way that surpassed all previous efforts.

And he was successful thanks to his 62-foot-high triangular gnomon, the hypotenuse of which runs parallel to the earth’s axis, while its huge quadrants are parallel to the equator, and some other very impressive instruments. Taking a selfie before them, like I see other visitors do, I think that the structures do much more than look great in a photo. They’re a reminder of how much can be achieved by human ambition and endeavour.

Appeared in the October 2015 issue as “Like Clockwork”.

The Guide

Although a total of five Jantar Mantars were built by Sawai Jai Singh II between 1717-1737, only four remain. At Mathura there is no trace of the once glorious observatory. Entrance rates below are given for Indian nationals and are higher for foreigners. The Jantar Mantars are generally open from 9 a.m. to 5 p.m. Time your visit for a sunny day, if you want to understand how the instruments work. 


The observatory in Delhi is one of the city’s most remarkable sights. Visitors can admire the beauty of the majestic reddish terracotta architecture while studying the intricacies of these massive instruments, each with a specific purpose. Everything is well signposted (located in a pleasant park a short walk south of Connaught Place, on Sansad Marg; entry5)

Ujjain, Madhya Pradesh

Ved Shala, as Ujjain’s Jantar Mantar is known locally, is still used as an observatory. Since it was restored in the early 20th century, astronomical findings and predictions are published annually. There is a planetarium with shows for schoolchildren. There’s also a library for those interested in astronomy (located a 20-minute walk southwest of the railway station; entry 10).

Jaipur, Rajasthan

Jaipur’s Jantar Mantar is the biggest of the four and everything here speaks of its builder, Sawai Jai Singh II’s greatness and ambition. It is also now a UNESCO World Heritage Site. Hire a guide to gain a deeper understanding of the site. Local astrologers still consult the instruments to forecast events (located south of the City Palace, behind Hawa Mahal; closes by 4.30 p.m.; entry 20; guide 100).

Varanasi, Uttar Pradesh

Jai Singh built this Jantar Mantar on the roof of an old palace, the Man Mandir. It is a small observatory and not as impressive as the others. It’s worth a visit for the equatorial sundial, which is said to be unique. The observatory also affords fabulous views of the city (located near Man Mandir Ghat, just north of the main Dasaswamedh Ghat; entry 5).





  • Zac O'Yeah is the author of the Bengaluru crime novel trilogy "Mr Majestic", "Hari, a Hero for Hire" and "Tropical Detective" (Pan Macmillan India) and his latest travel book is "A Walk Through Barygaza" (Amazon/Westland Books 2017).


Please Login to comment
48 Hours in Bahrain