An arched doorway leads to a staircase in the astronomical observatory called Jantar Mantar. The complex, located in the city of Jaipur in Rajasthan, India, was built by astronomer Jai Singh around 1730 and is still in use today. It includes large, abstract-looking structures designed to track the motion of the sun and tell time, among other uses.

Jantar Mantar is a Sanskrit phrase meaning “magical device.”

(Text and photograph from, "In the Land of the Maharajas: Rajasthan by Rail," Spring 1986, National Geographic Traveler magazine)