Which UNESCO World Heritage Site is a 17th-century astronomical observatory in Jaipur?

Jantar Mantar, Jaipur is the UNESCO World Heritage Site containing a remarkable 18th-century astronomical observatory built by Maharaja Jai Singh II.

The observatory was completed around 1734 and contains a collection of monumental masonry instruments. Their size allowed astronomers to make observations with considerable precision using shadows, angles, and alignments. The best-known instrument is the Samrat Yantra, a giant sundial described as the world’s largest stone sundial.

Jai Singh II established several observatories across northern India, but Jaipur’s is the largest and best preserved. The instruments were designed to observe celestial positions, calculate local time, and support astronomical predictions. They combine practical observation with the scientific traditions of the Mughal and wider Islamic worlds.

The date is a frequent source of confusion: the observatory belongs to the early 18th century, not the 17th century. Jaipur’s broader historic monuments, including Amber Fort and Hawa Mahal, are not the UNESCO property named in this question.