Constructed entirely of local stone and marble, the Jantar Mantar in Jaipur is the largest and best preserved of India’s historic observatories. Built in the early 1700s by the scholarly Maharaja Jai Singh II, the site’s monumental instruments measure and predict astronomical events with extraordinary precision. Noteworthy are the Samrat Yantra, a 27-meter-high sundial still accurate within two seconds, and a duo of sunken hemispheres that allow observers reclining within to track celestial movements. .
