Jantar Mantar, Jaipur. This amazing astronomical observation site was built in the early 18th century. Ahead-of-its-time contemporary design includes soaring stairways and sweeping lines. Fixed instruments allow observation of astronomical positions with the naked eye. Its creation under Maharaja Jai Singh II of Jaipur, became a meeting point for scientific discussion and gave rise to practices linked to cosmology. (Also, of course, it allowed rulers to control time and display authority.) This architectural and scientific wonder is a UNESCO World Heritage Site located in the city center of Jaipur in Rajasthan.