Jantar Mantar in Jaipur is an 18th-century observatory built to study the sky with the naked eye (yep, no telescopes). It's a small, accessible, and quite straightforward site to visit, and you get to tick both this site and Jaipur in one go. I visited Jantar Mantar twice (Dec 2013 and Dec 2023) and spent no more than an hour on both visits.

1. A UNESCO site within a UNESCO site

I used to share the opinion that Jantar Mantar as a separate site from Jaipur seemed confusing. I mean, it is well within Jaipur City’s core zone and is an integral part of the city palace’s compound. However, Jantar Mantar as a separate site has its own merits, and as I see it, India intended it that way. Its OUV rests on being an excellent example of an 18th-century architectural ensemble of scientific and technical instruments. It is also a testament to the monarch's (Jai Singh II) patronage of astronomy and cosmology, and sort of a reflection of the rich artistic and scientific culture at the time. It also fills the gap in heritage sites that are devoted to astronomy (see ICOMOS Thematic Study on Astronomical Heritage in 2010). Jaipur City’s focus is obviously way different. I reckon its separation from Jaipur City does not make Jaipur’s OUV anything less, and vice versa, and that they can stand on their own.

2. Highlights

Jantar Mantar has some 20 instruments crafted with seemingly geometric precision.I took some time to take a good look at these instruments on my second visit, as I only zoomed through this site back in Dec 2013. I have noted the instruments' purpose without really understanding (or wanting to understand) how they work.  These instruments stood out to me:

• Samrat Yantra - this is the tall triangular structure that dominates the observatory. There is a cute cupola or chhatri at the very top of the structure. It is basically a giant sundial capable of accurately measuring time.
• Rama Yantra - a couple of cylindrical structures that are used to measure the position of a celestial object (e.g., the altitude of a star). Check out the scales on the walls of the structure--you can see the precision required in constructing these structures.
• Jai Prakash - it is a hemispherical, bowl-shaped instrument in the ground of an elevated platform. Notice the lines and markings on the instrument that correspond to the altitude and azimuth of the horizontal coordinate system. This instrument is quite popular.
• Nadivalaya Yantra - this is also a sundial (see photo).
• Rasivalaya Yantra - these are 12 of these miniature versions of the Samrat Yantra, each corresponding to a zodiac constellation. Notice the drawings that represent each of the zodiacs. 

3. On other observatories named Jantar Mantar

Jai Singh II also commissioned the construction of observatories named Jantar Mantar in other cities: Delhi, Ujjain, Mathura, and Varanasi. Unfortunately, I haven't visited any of these other observatories, though I did check them out on Google Maps. Not visiting the one in Delhi was a real disappointment since it is situated between the sites we visited there. The observatories in these cities have fewer instruments and are smaller in scale compared to the Jantar Mantar in Jaipur. It's quite notable to me that the instruments in Jaipur and Varanasi are painted cream-yellow, while the ones in Delhi and Ujjain are in red and white, respectively.

I believe it was a good decision to exclude these observatories from the nomination, as the Jantar Mantar in Jaipur sufficiently represents what it claims as OUV. The state of conservation of the other observatories might have also been a factor at the time of the nomination. For example, the Jantar Mantar in Varanasi currently appears unkempt and littered with rubbish when viewed on Google Maps, and I wouldn't be surprised if it was in a similar condition back in 2010. Also, the Jantar Mantar in Mathura was demolished back in the mid-19th century.